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Learning Objectives
After studying this chapter, you should be able to:
• Describe how solar and wind power systems work and how—along with other forms of renewable energy—these technologies can help us move away from a dependence on fossil fuel energy sources.
• Explain how hydropower and geothermal energy systems work, and review their advantages and disad- vantages relative to other forms of energy.
• Discuss the major drawbacks of nuclear power and why this technology may not be the best approach to reducing the carbon footprint of our energy system.
• Explain what energy efficiency means and how efficiency can help us meet our energy needs while simultaneously reducing energy consumption and the environmental impacts of energy use.
• Describe the features and components of a net-zero energy office building and how a combination of technology and behavioral changes help these buildings use only as much energy as they produce.
Renewable Energy, Nuclear Power, and Energy Efficiency 8
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IntroDuctIon
Pre-Test
1. Which of the following is not one of the policy options recommended to help speed up the adoption of renewable energy technologies?
a. Implementation of a feed-in tariff b. taxing fossil fuels to reflect their externality costs c. Subsidizing corn ethanol production d. Investing in an improved long-distance power transmission system 2. It could be said that hydroelectric power is always renewable and always sustainable. a. true b. False 3. Which of the following is not a radioactive byproduct of nuclear power production? a. cesium-137 b. Plutonium c. Strontium-90 d. Bauxite 4. Energy efficiency focuses more on the supply side than the demand side. a. true b. False 5. A “net-zero energy” building is designed to use no energy at all. a. true b. False
Answers 1. c. Subsidizing corn ethanol production. the answer can be found in section 8.1. 2. b. False. the answer can be found in section 8.2. 3. d. Bauxite. the answer can be found in section 8.3. 4. b. False. the answer can be found in section 8.4. 5. b. False. the answer can be found in section 8.5.
Introduction Walk around your home and take note of all of the devices that you leave plugged in whether or not they are in use. televisions, computers, refrigerators, alarm clocks, and cell phone chargers all constantly use energy. next, try to imagine the sum of such energy consumption that occurs in the more than 100 million households across the entire united States. Add to that all of the electricity, home and commercial heating and cooling, manufacturing, and fuel used to power various methods of transportation. now, still in your imagination, expand this sum of consumption to include all the other countries throughout the world.
the staggering sum of energy consumption across the world has been quantified by the Energy Information Agency (EIA) of the united States. the EIA estimates that world energy consumption was approximately 500 quadrillion Btu (British thermal units) in 2010 (u.S. Energy Information Administration, 2010). It’s difficult to attach a human scale to this num- ber. Five hundred quadrillion Btu is the energy equivalent of 10 million atomic bombs of the size dropped on Hiroshima in 1945. And by 2035, the EIA predicts that global energy con- sumption will increase to 770 quadrillion Btu.
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When we look into the future, we face the certainty that fossil fuel reserves will become depleted. Indeed, in 2010 about 90 percent of global energy supply was furnished by fossil fuels (BP, 2010). Experts agree that alternative energy sources must be developed in order to keep up with global energy demands and avoid catastrophic climate changes. not surpris- ingly, though, experts also disagree over whether there is sufficient will and investment to convert to an alternative energy economy without a significant change in our lifestyles. In this chapter we will examine the risks of using nuclear energy sources, as well as explore the plausibility of using various renewable energy sources as we seek the answer to the following question: can global society make the massive shift to using wind turbines, solar power, and other renewable energy sources to replace the current reliance on fossil fuels?
the two most important sources of renewable energy reviewed in this chapter are solar and wind power. We’ll see that solar comes in a variety of forms, including solar photovoltaic (PV) panels that can be placed on rooftops to generate electricity and large-scale concentrat- ing solar power (cSP) systems that use mirrors to concentrate the sun’s rays and generate electricity. the power of the wind can be harnessed by wind turbines that, when grouped together in one area, are referred to as a wind farm. other renewable energy sources touched on to varying degrees in this chapter include a variety of water-based sources including hydropower, wave power, and tidal power; geothermal energy or energy from the ground; and a variety of forms of biomass energy derived from plants and other living organisms. In addition, the chapter will have a lot to say about energy efficiency—an approach to using less energy while accomplishing the same tasks and amount of work.
A key difference between non-renewable and renewable energy sources can be illustrated through the concepts of stocks and flows. non-renewable energy sources such as oil and coal currently exist in fixed amounts or stocks. We cannot hope for any significant increase in these stocks. the high-energy content and versatility in use of these fossil fuel stocks makes them especially attractive as a form of energy. In contrast, renewable energy sources such as wind and sunlight are available not as fixed stocks of energy but as flows. these flows are renewable in that the sun will keep shining and the wind will keep blowing no matter how much we make use of them. In addition, these flows are massive—the total energy contained in one hour of sunlight shining on the Earth is more than all of the commercial energy con- sumed on the planet in one year, and the energy contained in wind represents more than 15 times the global energy demand.
However, unlike highly energy-dense fossil fuels, these renewable energy flows are diffuse and intermittent. We have to deploy and develop extensive areas of solar panels and wind turbines to capture enough energy to meet demand, and we have to account for the fact that in a given location, on a particular day, the sun may not shine or the wind may not be strong enough to generate power. In this way we can categorize non-renewable fossil fuel energy sources as stock-limited and renewable energy sources as flow-limited.
In order to more effectively make use of renewable energy technologies, we must pair their adoption with improvements in the efficiency of energy use. By first reducing energy demand through better lighting, appliances, windows, and insulation, we can reduce the quantity and magnitude of the renewable energy devices that need to be put in place to meet remain- ing energy demand. this concept of synergy between renewable energy and energy effi- ciency is best illustrated in so-called net-zero energy homes or buildings (see section 8.5).
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Such structures produce as much energy as they consume over the course of a day, week, or month, and represent the feasibility of utilizing renewable energy sources to meet much of our energy needs. We also need to pay attention to issues of energy storage and how energy is distributed through the electric power grid. For renewable energy sources to really increase in prominence and importance, we’ll need to improve our electric grid so that power gener- ated from renewable sources can be distributed when and where it is needed.
one additional note on the terminology used in many of the readings in this chapter: A watt is a unit of energy, and the readings will refer to things like a megawatt (one million watts) and a terawatt (one trillion watts). For our purposes it might be easier to put these units into per- spective. For example, when the authors in section 8.1 refer to wind turbines that are rated at five megawatts capacity, they are describing a piece of equipment that, when operating at full capacity, can produce five megawatts of electric power. this is enough electricity to meet the needs of roughly 1,700 American households. the main issue that we’ll see with renewable energy is developing enough variety in sources so that energy needs are met in a specific loca- tion even if the wind is not blowing (or sun is not shining) at that moment.
8.1 Powering the World With Renewable Energy Chapter 7 made clear that if we are to avoid the worst consequences of global climate change, we will soon need to shift away from a reliance on fossil fuels and move toward renewable energy sources. However, fossil fuel industries and their supporters often claim that renewable energy is expensive, unreliable, and unable to meet the bulk of our energy needs for the foreseeable future. In this article environmental scientists Mark Jacobson and Mark Delucchi challenge that claim and describe their plan for how the world can shift to renewable energy for 100 percent of its power needs by 2030. Specifically, Jacobson and Delucchi focus on a combination of wind, water, and sunlight (WWS) renewable energy systems to achieve this goal. Renewable energy sources offer numerous benefits, including that they can be produced domestically, they never “run out,” and they are virtually pollution free.
One major benefit of renewable solar energy is that it can be utilized in a number of different ways. Passive solar energy uses sunlight directly without any mechanical devices, such as when sunlight is used to illuminate or heat interior spaces. Active solar energy captures sunlight using mechanical devices and then converts it to useful heat or electric power. Solar photovoltaic or PV panels convert sunlight to electricity, which is the most common form of active solar energy. You can find PV panels on solar calculators, rooftops, and streetlights and traffic signs. Another way to generate electricity using solar energy is through solar thermal or concentrating solar power (CSP) systems. These systems use mirrors to concentrate the sun’s rays on a tank or pipe filled with fluid. The heated fluid can then be used to produce steam used to spin a turbine to generate electricity.
Wind turbines are mechanical devices that convert the kinetic energy of the wind into electric power. Wind power development has been accelerating in recent years in such countries as Ger- many, Spain, the United States, and China. In terms of percentage share of total energy, Denmark is the world leader with more than 20 percent of their electricity needs produced from wind power. Denmark uses wind turbines located both on land and in offshore regions near the coast. Such offshore areas have stronger and more consistent winds but are also more expensive to develop.
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Jacobson and Delucchi’s plan calls for over 90 percent of our energy needs to be met through solar and wind power sources. The remainder can be met by a mix of water-based and geo- thermal sources. Traditional hydroelectric power and geothermal energy are described in more detail in the next section, but it’s worth mentioning here what is meant by wave and tidal power. Wave power is essentially another form of wind power since it is designed to harness the energy of waves, which are driven by the winds. Tidal power takes advantage of differences in tides and the power of water moving with those tidal changes to also generate electricity. You can learn more about how wave and tidal power work by examining these sources ( http://www.ucsusa .org/clean_energy/our-energy-choices/renewable-energy/how-hydrokinetic-energy -works.html and http://science.howstuffworks.com/environmental/earth/oceanography /wave-energy1.htm) and others listed in the Additional resources section at the end of the chapter.
Finally, it’s important to point out the role that economics and politics play in a transition to renewable energy. Jacobson and Delucchi make clear that when you factor in the externality costs—the monetary value of health and environmental damage—of using fossil fuels, these sources of energy are often more expensive than they first appear. Combine that with the rapid rate of decline in the costs of renewable energy sources such as solar and wind and it becomes apparent that there are sound economic arguments in favor of a renewable energy system. While the economics are increasingly favorable for renewable energy, it is the lack of political will to implement these sources and strong lobbying of politicians by the fossil fuel industry that most impede their development. Ironically, fossil fuels are already among the most heavily subsidized industries in the world, especially in the United States. This reading calls for an elimination of those subsidies and the implementation of incentives to promote the development of renewable energy alternatives. Such a policy approach makes both economic and environmental sense but will require a change in our current political approach to energy issues.
By Mark Z. Jacobson and Mark A. Delucchi In December [2009] leaders from around the world will meet in copenhagen to try to agree on cutting back greenhouse gas emissions for decades to come. the most effective step to implement that goal would be a massive shift away from fossil fuels to clean, renewable energy sources. If leaders can have confidence that such a transformation is possible, they might commit to an historic agreement. We think they can. A year ago former vice president Al gore threw down a gauntlet: to repower America with 100 percent carbon-free electricity within 10 years. As the two of us started to evaluate the feasibility of such a change, we took on an even larger challenge: to determine how 100 percent of the world’s energy, for all pur- poses, could be supplied by wind, water and solar resources, by as early as 2030. our plan is presented here.
Scientists have been building to this moment for at least a decade, analyzing various pieces of the challenge. Most recently, a 2009 Stanford university study ranked energy systems according to their impacts on global warming, pollution, water supply, land use, wildlife and other concerns. the very best options were wind, solar, geothermal, tidal and hydroelectric
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power—all of which are driven by wind, water or sunlight (referred to as WWS). nuclear power, coal with carbon capture, and ethanol were all poorer options, as were oil and natural gas. the study also found that battery-electric vehicles and hydrogen fuel-cell vehicles recharged by WWS options would largely eliminate pollution from the transportation sector.
our plan calls for millions of wind tur- bines, water machines and solar instal- lations. the numbers are large, but the scale is not an insurmountable hurdle; society has achieved massive transfor- mations before. During World War II, the u.S. retooled automobile factories to produce 300,000 aircraft, and other countries produced 486,000 more. In 1956 the u.S. began building the Inter- state Highway System, which after 35 years extended for 47,000 miles, changing commerce and society.
Is it feasible to transform the world’s energy systems? could it be accom- plished in two decades? the answers depend on the technologies chosen, the availability of critical materials, and economic and political factors.
Clean Technologies Only renewable energy comes from enticing sources: wind, which also produces waves; water, which includes hydroelectric, tidal and geothermal energy (water heated by hot underground rock); and sun, which includes photovoltaics and solar power plants that focus sunlight to heat a fluid that drives a turbine to generate electricity. our plan includes only technologies that work or are close to working today on a large scale, rather than those that may exist 20 or 30 years from now.
to ensure that our system remains clean, we consider only technologies that have near-zero emissions of greenhouse gases and air pollutants over their entire life cycle, including con- struction, operation and decommissioning. For example, when burned in vehicles, even the most ecologically acceptable sources of ethanol create air pollution that will cause the same mortality level as when gasoline is burned. nuclear power results in up to 25 times more car- bon emissions than wind energy, when reactor construction and uranium refining and trans- port are considered. carbon capture and sequestration technology can reduce carbon dioxide emissions from coal-fired power plants but will increase air pollutants and will extend all the other deleterious effects of coal mining, transport and processing, because more coal must be
Consider This the main factor that determines whether a battery-electric car is “greener” than a gasoline-powered vehicle is how electric- ity is produced in a specific area. If a signif- icant portion of the electricity comes from renewable and clean sources like solar and wind, then a battery-electric car can be very green. However, in areas where elec- tricity comes mainly from coal, a gasoline- powered car might actually be “greener” than a battery-electric vehicle.
First read this article: http://www.ny times.com/2012/04/15/automobiles /how-green-are-electric-cars-depends -on-where-you-plug-in.html
next, explore the resources at this union of concerned Scientists site and determine how green a switch to a battery-electric vehicle would be in your area: http:// www.ucsusa.org/clean_vehicles/smart -transportation-solutions/advanced -vehicle-technologies/electric-cars /emissions-and-charging-costs-electric -cars.html
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burned to power the capture and storage steps. Similarly, we consider only technologies that do not present significant waste disposal or terrorism risks.
In our plan, WWS will supply electric power for heating and transportation—industries that will have to revamp if the world has any hope of slowing climate change. We have assumed that most fossil-fuel heating (as well as ovens and stoves) can be replaced by electric sys- tems and that most fossil-fuel transportation can be replaced by battery and fuel-cell vehicles. Hydrogen, produced by using WWS electricity to split water (electrolysis), would power fuel cells and be burned in airplanes and by industry.
Plenty of Supply today the maximum power consumed worldwide at any given moment is about 12.5 tril- lion watts (terawatts, or tW), according to the u.S. Energy Information Administration. the agency projects that in 2030 the world will require 16.9 tW of power as global popula- tion and living standards rise, with about 2.8 tW in the u.S. the mix of sources is similar to today’s, heavily dependent on fossil fuels. If, however, the planet were powered entirely by WWS, with no fossil-fuel or biomass combustion, an intriguing savings would occur. global power demand would be only 11.5 tW, and u.S. demand would be 1.8 tW. that decline occurs because, in most cases, electrification is a more efficient way to use energy. For example, only 17 to 20 percent of the energy in gasoline is used to move a vehicle (the rest is wasted as heat), whereas 75 to 86 percent of the electricity delivered to an electric vehicle goes into motion.
Even if demand did rise to 16.9 tW, WWS sources could provide far more power. Detailed studies by us and others indicate that energy from the wind, worldwide, is about 1,700 tW. Solar, alone, offers 6,500 tW. of course, wind and sun out in the open seas, over high moun- tains and across protected regions would not be available. If we subtract these and low-wind areas not likely to be developed, we are still left with 40 to 85 tW for wind and 580 tW for solar, each far beyond future human demand. yet currently we generate only 0.02 tW of wind power and 0.008 tW of solar. these sources hold an incredible amount of untapped potential.
the other WWS technologies will help create a flexible range of options. Although all the sources can expand greatly, for practical reasons, wave power can be extracted only near coastal areas. Many geothermal sources are too deep to be tapped economically. And even though hydroelectric power now exceeds all other WWS sources, most of the suitable large reservoirs are already in use.
The Plan: Power Plants Required clearly, enough renewable energy exists. How, then, would we transition to a new infrastruc- ture to provide the world with 11.5 tW? We have chosen a mix of technologies emphasiz- ing wind and solar, with about 9 percent of demand met by mature water-related methods. (other combinations of wind and solar could be as successful.)
Wind supplies 51 percent of the demand, provided by 3.8 million large wind turbines (each rated at five megawatts) worldwide. Although that quantity may sound enormous, it is inter- esting to note that the world manufactures 73 million cars and light trucks every year. Another 40 percent of the power comes from photovoltaics and concentrated solar plants, with about
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30 percent of the photovoltaic output from rooftop panels on homes and com- mercial buildings. About 89,000 photo- voltaic and concentrated solar power plants, averaging 300 megawatts apiece, would be needed. our mix also includes 900 hydroelectric stations worldwide, 70 percent of which are already in place.
only about 0.8 percent of the wind base is installed today. the worldwide foot- print of the 3.8 million turbines would be less than 50 square kilometers (smaller than Manhattan). When the needed spac- ing between them is figured, they would occupy about 1 percent of the earth’s land, but the empty space among turbines could be used for agriculture or ranching or as open land or ocean. the nonrooftop
photovoltaics and concentrated solar plants would occupy about 0.33 percent of the planet’s land. Building such an extensive infrastructure will take time. But so did the current power plant network. And remember that if we stick with fossil fuels, demand by 2030 will rise to 16.9 tW, requiring about 13,000 large new coal plants, which themselves would occupy a lot more land, as would the mining to supply them.
Smart Mix for Reliability A new infrastructure must provide energy on demand at least as reliably as the existing infrastructure. WWS technologies generally suffer less downtime than traditional sources. the average u.S. coal plant is offline 12.5 percent of the year for scheduled and unscheduled
maintenance. Modern wind turbines have a down time of less than 2 per- cent on land and less than 5 percent at sea. Photovoltaic systems are also at less than 2 percent. Moreover, when an individual wind, solar or wave device is down, only a small fraction of produc- tion is affected; when a coal, nuclear or natural gas plant goes offline, a large chunk of generation is lost.
the main WWS challenge is that the wind does not always blow and the sun does not always shine in a given location. Intermittency problems can be mitigated by a smart balance of sources, such as generating a base supply from steady geothermal or tidal power, relying on wind at night when it
. Felix-Andrei Constantinescu/iStock/Thinkstock
Energy demands can be more effectively met by diversifying the use of renewable energy sources, like wind and solar.
Consider This these short Energy 101 videos from the u.S. Department of Energy provide easy- to-understand explanations of how renew- able energy technologies actually work:
• Wind: http://energy.gov/videos /energy-101-wind-turbines
• Solar photovoltaics: http://energy .gov/videos/energy-101-solar-pv
• concentrating solar power: http:// energy.gov/videos/energy-101 -concentrating-solar-power
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is often plentiful, using solar by day and turning to a reliable source such as hydroelectric that can be turned on and off quickly to smooth out supply or meet peak demand. For example, interconnecting wind farms that are only 100 to 200 miles apart can compensate for hours of zero power at any one farm should the wind not be blowing there. Also helpful is intercon- necting geographically dispersed sources so they can back up one another, installing smart electric meters in homes that automatically recharge electric vehicles when demand is low and building facilities that store power for later use.
Because the wind often blows during stormy conditions when the sun does not shine and the sun often shines on calm days with little wind, combining wind and solar can go a long way toward meeting demand, especially when geothermal provides a steady base and hydroelec- tric can be called on to fill in the gaps.
Apply Your Knowledge one of the most common criticisms of wind power is that wind turbines are a major cause of bird and bat deaths. the u.S. Fish and Wildlife Service estimates that collisions with wind turbine blades kill close to 500,000 birds annually. However, this is a relatively small number compared to estimated bird deaths from other sources such as domestic cats and collisions with buildings, cell phone towers, and transmission lines. combined, these sources could be responsible for over one billion bird deaths annually. nevertheless, the wind power industry is exploring ways to better locate and construct wind turbines in order to minimize bird and bat mortality. Start by reviewing these readings on the subject:
• A detailed fact sheet on wind turbine interactions with birds and bats: http://national wind.org/wp-content/uploads/assets/publications/Birds_and_Bats_Fact_Sheet_.pdf
• An article on how researchers are seeking ways to reduce wind turbine-related bird and bat mortality: http://www.nature.com/news/the-trouble-with-turbines-an-ill -wind-1.10849
• A handful of short articles and graphics showing common causes of bird mortality: http://www.nytimes.com/2011/03/21/science/21birds.html, http://www.nssf.org /share/PDF/BirdMortality.pdf, and http://www.fws.gov/birds/mortality-fact-sheet.pdf
After you review this information, consider the following scenario. Suppose a new wind farm consisting of 80–100 new wind turbines is being proposed for development in a rural area near you, and that you’ve been asked to complete a wildlife impact assessment for this proj- ect. Where would you start? What might you do to try to determine whether this wind farm would pose a serious threat to birds and bats in the area? Suppose the wind power developer informed you that they had a new device that they planned to attach to wind turbines to deter birds before they can collide with the structure. How might you design a scientific experiment to test the effectiveness of such a device?
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As Cheap as Coal the mix of WWS sources in our plan can reliably supply the residential, commercial, indus- trial and transportation sectors. the logical next question is whether the power would be affordable. For each technology, we calculated how much it would cost a producer to gener- ate power and transmit it across the grid. We included the annualized cost of capital, land, operations, maintenance, energy storage to help offset intermittent supply, and transmission. today the cost of wind, geothermal and hydroelectric are all less than seven cents a kilowatt- hour (¢/kWh); wave and solar are higher. But by 2020 and beyond wind, wave and hydro are expected to be 4¢/kWh or less.
For comparison, the average cost in the u.S. in 2007 of conventional power generation and transmission was about 7¢/kWh, and it is projected to be 8¢/kWh in 2020. Power from wind turbines, for example, already costs about the same or less than it does from a new coal or natural gas plant, and in the future wind power is expected to be the least costly of all options. the competitive cost of wind has made it the second-largest source of new electric power generation in the u.S. for the past three years, behind natural gas and ahead of coal.
Solar power is relatively expensive now but should be competitive as early as 2020. A careful analysis by Vasilis Fthenakis of Brookhaven national laboratory indicates that within 10 years, photovoltaic system costs could drop to about 10¢/kWh, including long-distance transmission and the cost of compressed-air storage of power for use at night. the same analysis estimates that concentrated solar power systems with enough thermal storage to generate electricity 24 hours a day in spring, summer and fall could deliver electricity at 10¢/kWh or less.
transportation in a WWS world will be driven by batteries or fuel cells, so we should com- pare the economics of these electric vehicles with that of internal-combustion-engine vehi- cles. Detailed analyses by one of us (Delucchi) and tim lipman of the university of califor- nia, Berkeley, have indicated that mass-produced electric vehicles with advanced lithium-ion or nickel metal-hydride batteries could have a full lifetime cost per mile (including battery replacements) that is comparable with that of a gasoline vehicle, when gasoline sells for more than $2 a gallon.
When the so-called externality costs (the monetary value of damages to human health, the environment and climate) of fossil-fuel generation are taken into account, WWS technologies become even more cost-competitive.
overall construction cost for a WWS system might be on the order of $100 trillion worldwide, over 20 years, not including transmission. But this is not money handed out by governments or consumers. It is investment that is paid back through the sale of electricity and energy. And again, relying on traditional sources would raise output from 12.5 to 16.9 tW, requiring thousands more of those plants, costing roughly $10 trillion, not to mention tens of trillions of dollars more in health, environmental and security costs. the WWS plan gives the world a new, clean, efficient energy system rather than an old, dirty, inefficient one.
Political Will our analyses strongly suggest that the costs of WWS will become competitive with traditional sources. In the interim, however, certain forms of WWS power will be significantly more costly than fossil power. Some combination of WWS subsidies and carbon taxes would thus be
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needed for a time. A feed-in tariff (FIt) program to cover the difference between generation cost and wholesale electricity prices is especially effective at scaling-up new technologies. combining FIts with a so-called declining clock auction, in which the right to sell power to the grid goes to the lowest bidders, provides continuing incentive for WWS developers to lower costs. As that happens, FIts can be phased out. FIts have been implemented in a number of European countries and a few u.S. states and have been quite successful in stimulating solar power in germany.
taxing fossil fuels or their use to reflect their environmental damages also makes sense. But at a minimum, existing subsidies for fossil energy, such as tax benefits for exploration and extraction, should be eliminated to level the playing field. Misguided promotion of alterna- tives that are less desirable than WWS power, such as farm and production subsidies for biofu- els, should also be ended, because it delays deployment of cleaner systems. For their part, leg- islators crafting policy must find ways to resist lobbying by the entrenched energy industries.
Finally, each nation needs to be willing to invest in a robust, long-distance transmission sys- tem that can carry large quantities of WWS power from remote regions where it is often greatest—such as the great Plains for wind and the desert Southwest for solar in the u.S.—to centers of consumption, typically cities. reducing consumer demand during peak usage peri- ods also requires a smart grid that gives generators and consumers much more control over electricity usage hour by hour.
A large-scale wind, water and solar energy system can reliably supply the world’s needs, sig- nificantly benefiting climate, air quality, water quality, ecology and energy security. As we have shown, the obstacles are primarily political, not technical. A combination of feed-in tariffs plus incentives for provid- ers to reduce costs, elimination of fossil subsidies and an intelligently expanded grid could be enough to ensure rapid deployment. of course, changes in the real-world power and transportation industries will have to overcome sunk investments in existing infrastructure. But with sensible policies, nations could set a goal of generating 25 percent of their new energy supply with WWS sources in 10 to 15 years and almost 100 percent of new supply in 20 to 30 years. With extremely aggressive policies, all existing fossil-fuel capacity could theoretically be retired and replaced in the same period, but with more modest and likely poli- cies full replacement may take 40 to 50 years. Either way, clear leadership is needed, or else nations will keep trying technologies promoted by industries rather than vetted by scientists.
A decade ago it was not clear that a global WWS system would be technically or economically feasible. Having shown that it is, we hope global leaders can figure out how to make WWS power politically feasible as well. they can start by committing to meaningful climate and renewable energy goals now.
Consider This A far more detailed description of the 100 percent renewable energy plan described in this reading can be found in this two-part article by the same authors:
• http://www.stanford.edu/group /efmh/jacobson/Articles/I/JDEn PolicyPt1.pdf
• http://www.stanford.edu/group /efmh/jacobson/Articles/I/DJEn PolicyPt2.pdf
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SEctIon 8.2TradiTional renewables—Hydropower and GeoTHermal
Source: Jacobson, M. Z., & Delucchi, M. A. (2009 October). A Plan to Power 100 Percent of the Planet with Renewables. Scientific American. Retrieved from http://www.scientificamerican.com/article.cfm?id=a-path -to-sustainable-energy-by-2030 Reproduced with permission. Copyright © 2009 Scientific American, Inc. All rights reserved.
8.2 Traditional Renewables—Hydropower and Geothermal Decades before modern solar panels and wind turbines were developed, we used the energy con- tained in running water and under the Earth’s surface. Water-generated energy called hydro- electric power or hydropower taps the kinetic energy of moving water to generate electricity. For over a century dams have been built in the United States to exploit this energy resource. Geo- thermal power makes use of heated water that is deep underground to produce steam to gener- ate electricity. Because the water cycle keeps water moving, and because the geologic conditions that produce underground hot water and steam will continue to do so indefinitely, hydropower and geothermal power are considered renewable forms of energy.
In the first part of the following section staff writers with the United States Geological Survey (USGS) review advantages and disadvantages associated with the development and use of hydro- power resources. The main advantage is that hydropower generates electricity without fossil fuel combustion, so there are no direct emissions of pollutants or greenhouse gases. However, because hydropower usually involves the construction of a dam in order to create a reservoir to hold water in place, it can have a number of ecological and social impacts. These include the destruction of wildlife habitat and homes as well as modification of river flow patterns. In this sense it might be fair to say that hydroelectric power is renewable but not always sustainable.
In the second part of this section staff writers with the National Renewable Energy Laboratory (NREL) explain some of the basics of geothermal power. Geothermal resources can directly pro- vide hot water for industrial purposes or be converted to electricity through geothermal power plants. The article points out that even the low-grade geothermal energy that exists under- ground nearly everywhere can be tapped to heat and cool homes and buildings. Such geother- mal heat pump systems make use of the relatively constant temperature of 50 to 608F just ten feet below the Earth’s surface to cool spaces in the summer and heat them in the winter. Both hydroelectric and geothermal power fit into the 100 percent renewable energy plan described in section 8.1, along with wave and tidal power systems. However, these energy sources are far more location-specific (e.g., near water or geothermal resources) than wind or solar, so they are expected to play a less important role in meeting future energy needs.
By the United States Geological Survey
Hydropower Although most energy in the united States is produced by fossil-fuel and nuclear power plants, hydroelectricity is still important to the nation, as about 7 percent of total power is produced by hydroelectric plants. nowadays, huge power generators are placed inside dams. Water flowing through the dams spin turbine blades which are connected to generators. Power is produced and is sent to homes and businesses.
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World Distribution of Hydropower • Hydropower is the most important and widely-used renewable source of energy. • Hydropower represents 19% of total electricity production. • china is the largest producer of hydroelectricity, followed by canada, Brazil, and the
united States (Source: Energy Information Administration). • Approximately two-thirds of the economically feasible potential remains to be devel-
oped. untapped hydro resources are still abundant in latin America, central Africa, India and china.
Producing electricity using hydroelectric power has some advantages over other power- producing methods. let’s do a quick comparison:
Advantages to hydroelectric power: • Fuel is not burned so there is minimal pollution • Water to run the power plant is provided free by nature • Hydropower plays a major role in reducing greenhouse gas emissions • relatively low operations and maintenance costs • the technology is reliable and proven over time • It’s renewable—rainfall renews the water in the reservoir, so the fuel is almost
always there.
Disadvantages to power plants that use coal, oil, and gas fuel: • they use up valuable and limited natural resources • they can produce a lot of pollution • companies have to dig up the Earth or drill wells to get the coal, oil, and gas • For nuclear power plants
there are waste-disposal problems
Hydroelectric power is not perfect, though, and does have some disadvantages:
• High investment costs • Hydrology dependent
(precipitation) • In some cases, inundation of
land and wildlife habitat • In some cases, loss or modifi-
cation of fish habitat • Fish entrainment or passage
restriction • In some cases, changes in
reservoir and stream water quality
• In some cases, displacement of local populations
. Getty Images/Jupiterimages/Stockbyte/Thinkstock
While Glen Canyon Dam provides electricity to major cities of the American West, it has also impacted the Colorado River ecosystem. Before the dam’s construction, the section of river below Glen Canyon contained silty, warmer water, favoring native fish such as humpback chub and razorback sucker. Since the dam’s completion, water below the dam tends to be colder and to favor trout.
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Hydropower and the Environment Hydropower is nonpolluting, but does have environmental impacts Hydropower does not pollute the water or the air. However, hydropower facilities can have large environmental impacts by changing the environment and affecting land use, homes, and natural habitats in the dam area.
Most hydroelectric power plants have a dam and a reservoir. these structures may obstruct fish migration and affect their populations. operating a hydroelectric power
plant may also change the water tem- perature and the river’s flow. these changes may harm native plants and animals in the river and on land. res- ervoirs may cover people’s homes, important natural areas, agricultural land, and archeological sites. So build- ing dams can require relocating people. Methane, a strong greenhouse gas, may also form in some reservoirs and be emitted to the atmosphere.
Reservoir construction is “drying up” in the United States [H]ydroelectric power sounds great—so why don’t we use it to produce all of our power? Mainly because you need lots of water and a lot of land where you can build a dam and res- ervoir, which all takes a lot of money, time, and construction. In fact, most of the good spots to locate hydro plants have already been taken. In the early part of the century hydroelectric plants supplied a bit less than one-half of the nation’s power, but the number is down to about 10 percent today. the trend for the future will probably be to build small-scale hydro plants that can generate electricity for a single community.
[t]he construction of surface reservoirs has slowed considerably in recent years. In the mid- dle of the 20th century, when urbanization was occurring at a rapid rate, many reservoirs were constructed to serve peoples’ rising demand for water and power. Since about 1980, the rate of reservoir construction has slowed considerably.
Typical Hydroelectric Powerplant [sic] Hydroelectric energy is produced by the force of falling water. the capacity to produce this energy is dependent on both the available flow and the height from which it falls. Building up behind a high dam, water accumulates potential energy. this is transformed into mechanical energy when the water rushes down the sluice and strikes the rotary blades of turbine. the turbine’s rotation spins electromagnets which generate current in stationary coils of wire. Finally, the current is put through a transformer where the voltage is increased for long dis- tance transmission over power lines.
Consider This What are the most significant advantages and disadvantages associated with the development and use of hydropower? Based on a review of these, is this an energy source we should be trying to increase use of?
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Figure 8.1: Hydroelectric power generation
Hydroelectric dams generate electricity via the force of falling water. once a river is blocked by a dam to form a reservoir, the dam’s sluice gates can be opened, allowing falling water to push powerful turbines that generate electricity. the electric current is run through a transformer to prepare it for transmission to utility customers.
Hydroelectric-power production in the United States and the world [I]n the united States, most states make some use of hydroelectric power, although, as you can expect, states with low topographical relief, such as Florida and Kansas, produce very little hydroelectric power. But some states, such as Idaho, Washington, and oregon use hydroelec- tricity as their main power source. In 1995, all of Idaho’s power came from hydroelectric plants.
china has developed large hydroelectric facilities in the last decade and now lead[s] the world in hydroelectricity usage. But, from north to south and from east to west, countries all over the world make use of hydroelectricity—the main ingredients are a large river and a drop in elevation.
Adapted from (no date). Hydroelectric Power Water Use. United States Geological Survey (USGS). Retrieved from http://ga.water.usgs.gov/edu/wuhy.html
Building a tall dam allows water to fall from a great height, producing more energy. 1
As water flows in, it spins the turbine blades, generating a current from the coils of wire found in the generator. 2
The current then goes to the transformer, where the voltage travels over power lines to power homes and businesses. 3
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By National Renewable Energy Laboratory
Geothermal Energy Many technologies have been developed to take advantage of geothermal energy—the heat from the earth. this heat can be drawn from several sources: hot water or steam reservoirs deep in the earth that are accessed by drilling; geothermal reservoirs located near the earth’s surface, mostly located in the western u.S., Alaska, and Hawaii; and the shallow ground near the Earth’s surface that maintains a relatively constant temperature of 508–608F.
this variety of geothermal resources allows them to be used on both large and small scales. A utility can use the hot water and steam from reservoirs to drive generators and produce elec- tricity for its customers. other applications apply the heat produced from geothermal directly to various uses in buildings, roads, agriculture, and industrial plants. Still others use the heat directly from the ground to provide heating and cooling in homes and other buildings.
Geothermal Direct Use geothermal reservoirs of hot water, which are found a few miles or more beneath the Earth’s surface, can be used to provide heat directly. this is called the direct use of geothermal energy.
geothermal direct use has a long history, going back to when people began using hot springs for bathing, cooking food, and loosening feathers and skin from game. today, hot springs are still used as spas. But there are now more sophisticated ways of using this geothermal resource.
In modern direct-use systems, a well is drilled into a geothermal reservoir to provide a steady stream of hot water. the water is brought up through the well, and a mechanical system— piping, a heat exchanger, and controls—delivers the heat directly for its intended use. A dis- posal system then either injects the cooled water underground or disposes of it on the surface.
geothermal hot water can be used for many applications that require heat. Its current uses include heating buildings (either individually or whole towns), raising plants in greenhouses, drying crops, heating water at fish farms, and several industrial processes, such as pasteur- izing milk.
Geothermal Electricity Production geothermal power plants use steam produced from reservoirs of hot water found a few miles or more below the Earth’s surface to produce electricity. the steam rotates a turbine that activates a generator, which produces electricity.
there are three types of geothermal power plants: dry steam, flash steam, and binary cycle.
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Dry steam Dry steam power plants draw from underground resources of steam. the steam is piped directly from under- ground wells to the power plant where it is directed into a turbine/genera- tor unit. there are only two known underground resources of steam in the united States: the geysers in northern california and yellowstone national Park in Wyoming, where there’s a well- known geyser called old Faithful. Since yellowstone is protected from devel- opment, the only dry steam plants in the country are at the geysers.
Flash steam Flash steam power plants are the most common and use geothermal res- ervoirs of water with temperatures greater than 3608F (1828c). this very
hot water flows up through wells in the ground under its own pressure. As it flows upward, the pressure decreases and some of the hot water boils into steam. the steam is then sepa- rated from the water and used to power a turbine/generator. Any leftover water and con- densed steam are injected back into the reservoir, making this a sustainable resource.
Binary steam Binary cycle power plants operate on water at lower temperatures of about 2258–3608F (1078–1828c). Binary cycle plants use the heat from the hot water to boil a working fluid, usu- ally an organic compound with a low boiling point. the working fluid is vaporized in a heat exchanger and used to turn a turbine. the water is then injected back into the ground to be reheated. the water and the working fluid are kept separated during the whole process, so there are little or no air emissions.
Geothermal Heat Pumps geothermal heat pumps take advantage of the nearly constant temperature of the Earth to heat and cool buildings. the shallow ground, or the upper 10 feet of the Earth, maintains a temperature between 508 and 608F (108–168c). this temperature is warmer than the air above it in the winter and cooler in the summer.
geothermal heat pump systems consist of three parts: the ground heat exchanger, the heat pump unit, and the air delivery system (ductwork). the heat exchanger is a system of pipes called a loop, which is buried in the shallow ground near the building. A fluid (usually water or a mixture of water and antifreeze) circulates through the pipes to absorb or relinquish heat within the ground.
In the winter, the heat pump removes heat from the heat exchanger and pumps it into the indoor air delivery system. In the summer, the process is reversed, and the heat pump moves
AP Photo/Calpine
The only dry steam power plant in the United States, The Geysers, is located in the mountains of California. It has been tapping steam fields to produce power since the 1960s.
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heat from the indoor air into the heat exchanger. the heat removed from the indoor air during the summer can also be used to heat water, providing a free source of hot water.
geothermal heat pumps use much less energy than conventional heating sys- tems, since they draw heat from the ground. they are also more efficient when cooling your home. not only does this save energy and money, it reduces air pollution.
All areas of the united States have nearly constant shallow-ground temperatures, which are suitable for geothermal heat pumps.
Adapted from (no date). Geothermal Energy Basics. National Renewable Energy Laboratory (NREL). Retrieved from http://www.nrel.gov/learning/re_geothermal.html
8.3 Nuclear Power The March 2011 earthquake and tsunami that triggered a catastrophe at Japan’s Fukushima nuclear complex has reignited debates over the role and safety of nuclear power. Because nuclear power can generate electricity without carbon dioxide emissions, it has been identified as a potentially useful way to meet our energy needs in a “climate-friendly” manner. However, concerns over nuclear safety, the disposal of highly radioactive nuclear waste, and the high cost of nuclear construction have hindered the development of this energy source. In this section, Dr. Helen Caldicott, a pediatrician in Australia and the founding president of Physicians for Social Responsibility, explains some of the outcomes of the nuclear crisis in Japan.
Most nuclear reactors, including the ones damaged by the tsunami in Japan, are based on the concept of nuclear fission. In nuclear fission, the nucleus of a heavy element such as uranium is bombarded with neutrons causing it to split apart and release multiple neutrons along with heat and radiation. The neutrons released in this process can go on and bombard other uranium atoms and create a chain reaction, releasing massive amounts of energy in the process. This is the basic idea behind a nuclear bomb. In a nuclear power plant, the chain reaction is controlled, and the heat released in the fission process is used to boil water and produce steam to spin a turbine and generate electricity.
Caldicott points out some of the health effects resulting from the catastrophe that occurred in Japan, indicating that nuclear power is the only form of energy that leaves so little room for error. Further updates and information on the Fukushima nuclear disaster are provided in the Additional resources section at the end of this chapter.
Consider This Describe the basic difference between geo- thermal direct, geothermal electric, and geothermal heat pump systems.
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By Helen Caldicott
Nuclear Power No Answer to Climate Change Advocating nuclear power as an answer to global warming is analogous to prescribing smok- ing for weight loss.
nuclear reactors do not stand alone but rely on a massive industrial infrastructure using fos- sil fuel and other global warming gases.
renewable energy that is readily available, cheaper than nuclear and coal, and can rapidly avert global warming must be immediately implemented by global governments.
let’s examine the Fukushima disaster—Australia’s uranium fuelled the reactors.
on March 11, 2011, three reactors were online when a massive earth- quake disrupted their power supply, drowned the auxiliary diesel genera- tors in the basements, and submerged pumps supplying each with 3.79 mil- lion litres of cooling water a minute.
Within hours, the intensely hot radio- active cores in units 1, 2 and 3 had started to melt—while the zirconium metal cladding on the uranium fuel rods reacted with water—generating hydrogen which forcefully exploded in buildings of 1, 2, 3 and 4, releasing huge amounts of radioactive elements into the air. And 400 tonnes of highly radioactive water—a total of 245,000 tonnes—has been leaking into the Pacific daily since the accident. three molten cores, each weighing more than 100 tonnes, melted their way through 15 centimetres of steel in the reactor vessels, now rest on concrete floors of the severely cracked containment buildings.
Each core contains as much radiation as that released by 1000 Hiroshima-sized bombs with more than 200 different radioactive elements, lasting seconds to millions of years.
Each of these deadly radioactive poisons has its own specific pathway in the food chain and the human body. radioactive elements are tasteless, odourless and invisible. It takes many years for cancers and other radiation-related diseases to manifest—from five to 80 years.
children are 10 to 20 times more radio-sensitive than adults, and foetuses thousands of times more so. Females are more sensitive than males. radiation is cumulative. there is no safe dose. Each dose adds to the risk of developing cancer.
© Mainichi Newspaper/AFLO/AFLO/Nippon News/Corbis
In March 2011, a large earthquake off the coast of Japan triggered a tsunami that breached the Tokyo Electric Power Company’s Fukushima Daiichi I power plant’s sea walls, crippling it.
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radiation of the reproductive organs induces genetic mutations in the sperm and eggs, increasing the incidence of genetic diseases over future generations such as diabetes, cystic fibrosis, haemochromatosis and 6000 others.
Sea water beside Fukushima is highly contaminated with tritium, the highest level recorded. tritium causes birth defects, cancers of various organs including brain and ovaries, testicular atrophy and mental retardation. tritium concentrates in food and fish and remains radioac- tive for 120 years .
cesium, a potassium mimicker, concentrates in heart, endocrine organs and muscles where it induces cardiac irregularities, heart attacks, diabetes, hypothyroidism, thyroid cancer and rhabdomyosarcoma, a muscle cancer. cesium is radioactive for 300 years and concentrates in the food chain.
Strontium 90, poisonous for 300 years, is analogous to calcium, concentrating in grass and milk, then in bones, teeth and breast milk where it can cause bone cancer, leukaemia or breast cancer.
Plutonium lasts 240,000 years and is one of the most potent carcinogens—a millionth of a gram can cause cancer.
Plutonium resembles iron so it can induce cancers in the lung, liver, bone, testicle and ovary. It crosses the placenta, causing severe birth deformities.
Each reactor core contains 150 kilograms of plutonium, and five kilograms is sufficient to make an atomic bomb. So nuclear power plants are essentially timeless bomb factories.
Iodine 131, radioactive for 100 days, is a potent carcinogen. Already 44 childhood thyroid cancers are suspected in Fukushima. thyroid cancer is extremely rare in young children.
More than 350,000 children still live in highly radioactive areas. leukaemia and solid cancers of various organs will increase for the next 70 to 80 years in this generation. About 2 million people in Japan live in highly contaminated areas.
Food in the contaminated zone will be radioactive for hundreds of years as it concentrates radiation. So cancer will devastate many future Japanese generations.
Japanese doctors are reporting that they have been ordered not to tell patients that their problems are radiation related.
the levels of radiation in buildings 1, 2 and 3 are now so high humans cannot enter or get close to the molten cores. It will be impossible to remove these cores for hundreds of years— if ever.
Should one of these buildings collapse during another earthquake, the targeted flow of cooling water to the pools and cores would cease and the cores would become red hot, releasing massive amounts of radiation into the air and water. Fuel in five cooling pools could also ignite.
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Building 4 is severely damaged. A vul- nerable cooling pool situated on the roof contains 250 tonnes of very hot fuel rods which were removed from the reactor just before the earthquake struck. Although the rods and their holding racks are still intact, they are geometrically deformed due to the force of the hydrogen explo- sion and will be dangerous to remove.
A large earthquake disrupting the integrity of the building could cause it to collapse, taking down the pool. Zirconium cladding the rods would burn, releasing the equivalent of 14,000 Hiroshima-sized bombs and 10 times more cesium than chernobyl, polluting much of Japan and the northern hemisphere.
While atmospheric radiation will largely remain in the north, radioactive water and polluted fish will continue to migrate across the Pacific, affecting Hawaii, north America, South Amer- ica and, eventually, Australia.
Caldicott, H. (2013, October 7). Nuclear power no answer to climate change. the Age. Retrieved from http://www .theage.com.au/comment/nuclear-power-no-answer-to-climate-change-20131007-2v3vu.html. Reprinted with permission.
8.4 Energy Efficiency Although much attention is focused on the potential for renewable energy sources such as solar and wind, relatively little consideration is given to the idea of energy efficiency. Energy efficiency can be defined as achieving the same outcome (lighting a room, driving a mile) while using less energy. The logic behind the pursuit of energy efficiency is simple: lowering energy demand through efficiency means reducing the need to produce energy in the first place—regardless of where that energy actually comes from. In the following reading, Eberhard K. Jochem of the Swiss Federal Institute of Technology provides examples of energy efficiency in action and sug- gests ways to boost the efficiency of energy use in the future.
Just as section 5.4 discussed reducing water demand as a means of addressing potential water shortages, energy efficiency focuses on the demand side of the equation rather than the supply side. Aggressive efforts to improve the efficiency of energy use in cars, homes, and businesses bring multiple benefits. Improved vehicle efficiency could reduce oil demand and decrease our dependence on foreign oil sources. More efficient use of electricity in homes and businesses could reduce the need to burn as much coal in power plants and reduce both local/regional air pollu- tion as well as greenhouse gas emissions.
However, there are economic and political barriers to more widespread adoption of energy effi- ciency measures. Because energy efficiency typically involves an upfront cost with payback over
Consider This What are some of the major risks associ- ated with the use of nuclear power? How do these risks add to the cost of this form of energy?
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Consider This How much energy is lost in the conversion from primary energy to final energy and then on to useful energy? How does energy efficiency help to reduce these losses?
time—for example, adding insulation to a home or installing new, energy-efficient windows— many homeowners and businesses hesitate or are unable to make such investments. Politically, energy efficiency does not seem as exciting as new energy sources like wind and solar, nor does it have a political lobby behind it the way fossil fuels do. These and other barriers can be over- come through policies such as tax incentives for energy-efficient investments and better label- ing of efficient appliances. Renewable energy sources are far more feasible and impactful when combined with energy efficiency efforts. We will see this clearly in section 8.5, which reviews a net-zero energy building that is so efficient it can easily meet its overall energy needs through renewable sources.
By Eberhard K. Jochem the huge potential of energy efficiency measures for mitigating the release of greenhouse gases into the atmosphere attracts little attention when placed alongside the more glamor- ous alternatives of nuclear, hydrogen or renewable energies. But developing a comprehensive efficiency strategy is the fastest and cheapest thing we can do to reduce carbon emissions. It can also be profitable and astonishingly effective, as two recent examples demonstrate.
From 2001 through 2005, Procter & gamble’s factory in germany increased production by 45 percent, but the energy needed to run machines and to heat, cool and ventilate buildings rose by only 12 percent, and carbon emissions remained at the 2001 level. the major pillars supporting this success include highly efficient illumination, compressed-air systems, new designs for heating and air conditioning, funneling heat losses from compressors into heating buildings, and detailed energy measurement and billing. In some 4,000 houses and build- ings in germany, Switzerland, Austria and Scandinavia, extensive insulation, highly efficient windows and energy-conscious design have led to enormous efficiency increases, enabling energy budgets for heating that are a sixth of the requirement for typical buildings in these countries. Improved efficiencies can be realized all along the energy chain, from the conver- sion of primary energy (oil, for example) to energy carriers (such as electricity) and finally to useful energy (the heat in your toaster). the annual global primary energy demand is 447,000 petajoules (a petajoule is roughly 300 gigawatt-hours), 80 percent of which comes from carbon-emitting fossil fuels such as coal, oil and gas. After conversion these primary energy sources deliver roughly 300,000 petajoules of so-called final energy to customers in the form of electricity, gasoline, heating oil, jet fuel, and so on.
the next step, the conversion of electric- ity, gasoline, and the like to useful energy in engines, boilers and lightbulbs, causes further energy losses of 154,000 pet- ajoules. thus, at present almost 300,000 petajoules, or two thirds of the primary energy, are lost during the two stages of energy conversion. Furthermore, all useful energy is eventually dissipated as heat at various temperatures. Insulating
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buildings more effectively, changing industrial processes and driving lighter, more aerody- namic cars would reduce the demand for useful energy, thus substantially reducing energy wastage.
given the challenges presented by climate change and the high increases expected in energy prices, the losses that occur all along the energy chain can also be viewed as opportu- nities—and efficiency is one of the most important. new technologies and know-how must replace the present intensive use of energy and materials.
Room for Improvement Because conservation measures, whether incorporated into next year’s car design or a new type of power plant, can have a dramatic impact on energy consumption, they also have an enormous effect on overall carbon emissions. In this mix, buildings and houses, which are notoriously inefficient in many countries today, offer the greatest potential for saving energy. In countries belonging to the organization for Economic cooperation and Development (oEcD) and in the megacities of emerging countries, buildings contribute more than one third of total energy-related greenhouse gas emissions.
little heralded but impressive advances have already been made, often in the form of effi- ciency improvements that are invisible to the consumer. Beginning with the energy crisis in the 1970s, air conditioners in the u.S. were redesigned to use less power with little loss in cooling capacity and new u.S. building codes required more insulation and double-paned win- dows. new refrigerators use only one quarter of the power of earlier mod- els. (With approximately 150 million refrigerators and freezers in the u.S., the difference in consumption between 1974 efficiency levels and 2001 levels is equivalent to avoiding the genera- tion of 40 gigawatts at power plants.) changing to compact fluorescent light- bulbs yields an instant reduction in power demand; these bulbs provide as much light as regular incandescent bulbs, last 10 times longer and use just one fourth to one fifth the energy.
. AlexMax/iStock/Thinkstock
Replacing incandescent lightbulbs with energy- efficient alternatives, like compact fluorescent or LED bulbs, is one way to reduce energy consumption at work and home.
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Despite these gains, the biggest steps remain to be taken. Many buildings were designed with the intention of minimizing construction costs rather than life-cycle cost, including energy use, or simply in ignorance of energy-saving considerations. take roof overhangs, for exam- ple, which in warm climates traditionally measured a meter or so and which are rarely used today because of the added cost, although they would control heat buildup on walls and win- dows. one of the largest European manufacturers of prefabricated houses is now offering
Apply Your Knowledge While a lot of attention gets paid to the potential for renewable energy sources like wind power and solar, relatively little is given to how energy efficiency and conservation can reduce our overall energy use. this is in large part due to the fact that most people have very little understanding of how they even use energy and how they might use it more efficiently. How- ever, there are dozens of websites available to help you estimate your own energy use and then find ways to reduce it. For example, explore the energy audit and calculator options at the sites listed below, the first focused on gasoline use and the remainder on electricity and natural gas:
http://www.learner.org/jnorth/tm/caribou/EnergyAudit.html—Work through the personal energy audit and fill in the missing figures on this page to get a sense of how much gasoline you are using annually. consider the “Journaling Questions” at the bot- tom of the page.
listed below are home energy consumption calculators offered by various electric and gas utility companies in different regions of the u.S. Pick one of these and provide infor- mation on your appliance and device usage so as to calculate how much energy you are using. or, try completing two or more and see how the results compare.
• http://www2.cmpco.com/Energycalculator/input.jsp • https://www.progress-energy.com/app/energycalculator/energycalculator.aspx • http://www.cpsenergy.com/residential/Information_library/calculators.asp • https://www.pacificpower.net/res/sem/eeti/euc.html • http://www.cpi.coop/my-account/online-usage-calculator/
After completing these audits and calculations, visit the following web pages and briefly review the suggestions for using less energy:
• http://energy.gov/sites/prod/files/energy_savers.pdf • http://www.alliantenergy.com/SaveEnergyAndMoney/tipsforSavingEnergy/index
.htm • http://www.pge.com/en/myhome/saveenergymoney/savingstips/index.page • http://www.energystar.gov/index.cfm?c=products.pr_save_energy_at_home
What are three specific things that you can do to reduce your own energy use? Why aren’t you already doing these things? What are some reasons more people don’t practice energy efficiency? If you were put in charge of developing a public relations campaign to increase adoption of energy efficiency practices, what are some things you might do?
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zero-net-energy houses: these well-insulated and intelligently designed structures with solar-thermal and photovoltaic collectors do not need commercial energy, and their total cost is similar to those of new houses built to conform to current building codes. Because build- ings have a 50- to 100-year lifetime, efficiency retrofits are essential. But we need to coordi- nate changes in existing buildings thoughtfully to avoid replacing a single component, such as a furnace, while leaving in place leaky ducts and single-pane windows that waste much of the heat the new furnace produces. one example highlights what might be done in industry: although some carpet manufacturers still dye their products at 100 to 140 degrees celsius, others dye at room temperature using enzyme technology, reducing the energy demand by more than 90 percent.
The Importance of Policy to realize the full benefits of efficiency, strong energy policies are essential. Among the under- lying reasons for the crucial role of policy are the dearth of knowledge by manufacturers and the public about efficiency options, budgeting methods that do not take proper account of the ongoing benefits of long-lasting investments, and market imperfections such as external costs for carbon emissions and other costs of energy use. Energy policy set by governments has tra- ditionally underestimated the benefits of efficiency. of course, factors other than policy can drive changes in efficiency—higher energy prices, new technologies or cost competition, for instance. But policies—which include energy taxes, financial incentives, professional train- ing, labeling, environmental legislation, greenhouse gas emissions trading and international coordination of regulations for traded products—can make an enormous difference. Further-
more, rapid growth in demand for energy services in emerging countries provides an opportunity to implement energy- efficient policies from the outset as infra- structure grows: programs to realize efficient solutions in buildings, transport systems and industry would give people the energy services they need without having to build as many power plants, refineries or gas pipelines.
Japan and the countries of the European union have been more eager to reduce oil imports than the u.S. has and have encouraged productivity gains through energy taxes and other measures. But all oEcD countries except Japan have so far failed to update appliance stan- dards. nor do gas and electric bills in oEcD countries indicate how much energy is used for heating, say, as opposed to boiling water or which uses are the most energy-intensive—that is, where a reduction in usage would produce the greatest energy savings. In industry, com- pressed air, heat, cooling and electricity are often not billed by production line but expressed as an overhead cost.
nevertheless, energy efficiency has a higher profile in Europe and Japan. A retrofitting project in ludwigshafen, germany, serves as just one example. Five years ago 500 dwellings were equipped to adhere to low-energy standards (about 30 kilowatt-hours per square meter per year), reducing the annual energy demand for heating those buildings by a factor of six.
Consider This What are some of the most important barriers to more widespread adoption of energy efficiency? How can these barriers be overcome?
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Before the retrofit, the dwellings were difficult to rent; now demand is three times greater than capacity.
other similar projects abound. the Board of the Swiss Federal Institutes of technology, for instance, has suggested a technological program aimed at what we call the 2,000-Watt Soci- ety—an annual primary energy use of 2,000 watts (or 65 gigajoules) per capita. realizing this vision in industrial countries would reduce the per capita energy use and related carbon emissions by two thirds, despite a two-thirds increase in gDP, within the next 60 to 80 years. Swiss scientists, including myself, have been evaluating this plan since 2002, and we have concluded that the goal of the 2,000-watt per capita society is technically feasible for indus- trial countries in the second half of this century.
to some people, the term “energy efficiency” implies reduced comfort. But the concept of efficiency means that you get the same service—a comfortable room or convenient travel from home to work—using less energy. the Eu, its member states and Japan have begun to tap the substantial—and profitable—potential of efficiency measures. to avoid the rising costs of energy supplies and the even costlier adaptations to climate change, efficiency must become a global activity.
Adapted from Jochem, E. K. (2006, September). An Efficient Solution. Scientific American, 64–67. Reproduced with permission. Copyright © 2006 Scientific American, Inc. All rights reserved.
8.5 Case History—A Zero Energy Office Building Commercial buildings are a significant consumer of energy in our society and a major source of carbon dioxide emissions. In this article, Kirk Johnson of the new york times profiles a fas- cinating experiment in constructing a “net-zero energy” commercial office building. A net-zero building is designed to produce as much energy as it uses over the course of a day, week, month,
Consider This the u.S. Department of Energy provides a wealth of information on energy efficiency and how you can save energy (and money) in your own home or apartment:
• http://energy.gov/public-services/homes/home-weatherization/home-energy-audits • http://energy.gov/videos/common-sense-and-next-30-seconds • http://www1.eere.energy.gov/multimedia/video_lighting_choices.html • http://www1.eere.energy.gov/multimedia/video_lumens.html • http://energy.gov/videos/energy-101-cool-roofs • http://energy.gov/videos/energy-101-daylighting • http://energy.gov/energysaver/articles/energy-efficient-home-design • http://energy.gov/public-services/homes/home-weatherization • http://energy.gov/public-services/homes/saving-electricity • http://energy.gov/public-services/homes/heating-cooling • http://energy.gov/public-services/homes/water-heating
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or year. The National Renewable Energy Lab (NREL) building in Golden, Colorado, is designed to do just that. The building is first and foremost designed to be ultra energy efficient. Because even the most energy-efficient building still needs energy, it also incorporates renewable sources of energy, including a solar photovoltaic system, into its design. An interesting fact about this project is that it has been done using existing technologies and at a cost that is comparable to traditional building designs.
Many homes, offices, and other buildings built in the United States suffer from what is sometimes called a principal-agent problem. The principal-agent problem is when one person or business makes decisions that will have a large impact on energy consumption while another person or business actually pays the energy bills. Many home and office builders cut corners on energy- efficient features during construction in order to keep costs down. Likewise, they are unlikely to include any renewable energy features in construction. However, once the home or office is occupied, a different person has to live with and pay for these decisions. Some builders do invest in energy-efficient insulation, windows, and appliances, and they seek an “efficiency premium” in return, but they are in the minority. Another good example of the principal-agent problem is the landlord who refuses to improve the efficiency of an apartment in cases where the tenant has to pay the energy bills.
There was no principal-agent problem in the design and construction of the NREL building in Colorado. From start to finish energy efficiency and renewable energy were prime objectives of the project. A key insight provided by this and other zero energy projects is that the potential for renewable energy is greatly enhanced when renewable technologies are paired with energy
efficiency. If a home or office building were energy inefficient it would require an enor- mous investment in solar panels or other renewable energy devices to meet energy demand. However, if energy demand can first be brought down by 30, 50, or 70 per- cent through efficiency measures, then a more modest investment in solar panels or other devices can meet the remaining demand for energy. Another key insight of this project is that if occupants of a build-
ing are provided with real-time information on how their behaviors influence energy consump- tion, they will often modify those behaviors in ways that can save significant amounts of energy over time.
By Kirk Johnson the west-facing windows by Jim Duffield’s desk started automatically tinting blue at 2:50 p.m. on a recent Friday as the midwinter sun settled low over the rocky Mountain foothills.
Around his plant-strewn work cubicle, low whirring air sounds emanated from speakers in the floor, meant to mimic the whoosh of conventional heating and air-conditioning systems, neither of which his 222,000-square-foot office building has, or needs, even here at 5,300 feet elevation. the generic white noise of pretend ductwork is purely for background and work- place psychology—managers found that workers needed something more than silence.
Consider This Define the principal-agent problem. How does it work to reduce or prevent invest- ments in energy efficiency?
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Meanwhile, the photovoltaic roof array was beating a retreat in the fading, low-angled light. It had until 1:35 p.m. been producing more electricity than the building could use—a three- hour energy budget surplus—interrupted only around noon by a passing cloud formation.
For Mr. Duffield, 62, it was just another day in what was designed, in painstaking detail, to be the largest net-zero energy office building in the nation. He’s still adjusting, six months after he and 800 engineers and managers and support staff from the national renewable Energy lab moved in to the $64 million building, which the federal agency has offered up as a tem- plate for how to do affordable, super-energy-efficient construction.
“It’s sort of a wonderland,” said Mr. Duffield, an administrative support worker, as the window shading system reached maximum.
Most office buildings are divorced, in a way, from their surroundings. Each day in the mechan- ical trenches of heating, cooling and data processing is much the same as another but for the cost of paying for the energy used.
the energy lab’s research Support Facility building is more like a mirror, or perhaps a sponge, to its surroundings. From the light-bending window louvers [a window covering with adjust- able slats] that cast rays up into the interior office spaces, to the giant concrete maze in the sub-basement for holding and storing radiant heat, every day is completely different.
Collecting Data this is the story of one randomly selected day in the still-new building’s life: Jan. 28, 2011.
It was mostly sunny, above-average temperatures peaking in the mid-60s, light winds from the west-northwest. the sun rose at 7:12 a.m.
By that moment, the central computer was already hard at work, tracking every watt in and out, seeking, always, the balance of zero net use over 24 hours—a goal that managers say probably won’t be attainable until early next year [2012], when the third wing of the project and a parking complex are completed.
With daylight, the building’s pulse quickened. the photovoltaic panels kicked in with electric- ity at 7:20 a.m.
As employees began arriving, electricity use—from cellphone chargers to elevators—began to increase. total demand, including the 65-watt maximum budget per workspace for all uses, lighting to computing, peaked at 9:40 a.m.
Meanwhile, the basement data center, which handles processing needs for the 300-acre cam- pus, was in full swing, peaking in electricity use at 10:10 a.m., as e-mail and research spread- sheets began firing through the circuitry.
For Mr. Duffield and his co-workers, that was a good-news bad-news moment: the data center is by far the biggest energy user in the complex, but also one of its biggest producers of heat, which is captured and used to warm the rest of the building. If there is a secret clubhouse for the world’s energy and efficiency geeks, it probably looks and feels just about like this.
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“nothing in this building was built the way it usually is,” said Jerry Blocher, a senior project manager at Haselden construction, the general contractor for the project.
the backdrop to everything here is that office buildings are, to people like Mr. Blocher, the unpicked fruit of energy conservation. commercial buildings use about 18 percent of the nation’s total energy each year, and many of those buildings, especially in years past, were designed with barely a thought to energy savings, let alone zero net use.
the answer at the research energy laboratory, a unit of the federal Department of Energy, is not gee-whiz science. there is no giant, expensive solar array that could mask a multitude of traditional design sins, but rather a rethinking of everything, down to the smallest elements, all aligned in a watt-by-watt march toward a new kind of building.
A Living Laboratory Managers even pride themselves on the fact that hardly anything in their building, at least in its individual component pieces, is really new.
off-the-shelf technology, cost-effi- cient as well as energy-efficient, was the mantra to finding what designers repeatedly call the sweet spot—zero energy that doesn’t break a sweat, or the bank. More than 400 tour groups, from government agency planners to corporations to architects, have trouped through since the first employ- ees moved in last summer.
“It’s all doable technology,” said Jef- frey M. Baker, the director of labora- tory operations at the Department of Energy’s golden field office. “It’s a liv- ing laboratory.”
Some of those techniques and tricks are as old as the great cathedrals of Europe (mass holds heat like a battery, which led to the concrete labyrinth in the subbasement). light, as builders
since the pyramids have known, can be bent to suit need, with louvers that fling sunbeams to white panels over the office workers heads’ to minimize electricity use.
there are certainly some things that workers here are still getting used to. In nudg- ing the building toward zero net electricity over 24 hours, lighting was a main target. that forced designers to lower the partition walls between work cubicles to only 42 or 54 inches (height decided by compass, or perhaps sundial, in maximizing the flow of natural light and ventilation), which raised privacy concerns among workers. Even the managers’ offices have no ceilings—again to allow the flow of natural light, as cast from the ceiling.
. Rick Wilking/Reuters/Corbis
Solar tubes on the roof of the U.S. National Renewable Energy Laboratory Research Support Facility bring light deep into the building. Natural light provided by the solar tubes help the building achieve net-zero energy use.
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Designing Green Behavior getting to the highest certification level in green building technology at reasonable cost also required an armada of creative decisions, large and small. the round steel structural columns that hold the building up? they came from 3,000 feet of natural gas pipe—built for the old energy economy and never used. the wood trim in the lobby? lodgepole pine trees—310 of them—killed by a bark beetle that has infested millions of acres of forest in the West.
ultimately, construction costs were brought in at only $259 a square foot, nearly $77 below the average cost of a new super-efficient commercial office building, according to figures from Haselden construction, the builder. other components of the design are based on observation of human nature.
People print less paper when they share a central printer that requires a walk to the copy room. People also use less energy, managers say, when they know how much they’re using. A monitor in the lobby offers real-time feedback on eight different measures.
the feedback comes right down to a worker’s computer screen, where a little icon pops up when the building’s central computer says conditions are optimal to crank the hand-opened windows. (other windows, harder to reach, open by computer command.)
Apply Your Knowledge one of the keys to developing an effective and efficient renewable energy economy is to know what forms of energy to develop where. large-scale development of solar energy facilities will make more sense in the sunny Southwest than it might in other regions, and wind and biomass are more readily available in some places than in others. this renewable energy map (http:// www.nrdc.org/energy/renewables/energymap.asp) developed by the natural resources Defense council (nrDc) shows existing renewable energy facilities on a state-by-state basis, as well as the potential for development of different forms of renewable energy. click on your state and review both the existing facilities and the potential for various renewable energy sources. next, review the following pages that provide detailed maps of the availability and potential for various renewable energy sources in different regions of the united States.
• links to maps showing biomass, geothermal, solar, and wind energy potential: http:// www.nrel.gov/gis/maps.html
• Information and maps on hydro-, wind, solar, geothermal, and biomass power: http:// www.nationalatlas.gov/articles/people/a_energy.html
Based on a review of the nrDc renewable energy map and the other sources of information, design a plan for your state to meet 100 percent of its energy requirements from renewable sources by the year 2050. What renewable energy sources feature most prominently in your plan and why? What role could energy efficiency play in achieving your goal? What kinds of policies would you put in place to make your plan achievable, and how would you present this plan to the public in order to gain their support?
“the open office is different,” said Andrew Parker, an engineer. “you want to be next to some- one quiet.”
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rethinking work shifts can also contribute. Here, the custodial staff comes in at 5 p.m., two or three hours earlier than in most traditional office buildings, saving on the use of lights.
the management of energy behavior, like the technology, is an experiment in progress.
“right now people are on their best behavior,” said ron Judkoff, a lab program manager. “time will answer the question of whether you can really train people, or whether a coffee maker or something starts showing up.”
Lessons Learned If Anthony castellano is a measure, the training regimen has clearly taken root. Mr. castellano, who joined the research laboratory last year as a Web designer after years in private industry, said the immersion in energy consciousness goes home with him at night.
“My kids are yelling at me because I’m turning off all the lights,” Mr. castellano said.
At 5:05 p.m., the solar cells stopped producing. Declining daylight in turn produced a brief spike in lighting use, at 5:55 p.m. Five minutes later, the building management system began shutting off lights in a rolling two-hour cycle (the computer gives a few friendly blinks, as a signal in case a late-working employee wants to leave the lights on).
Mr. Duffield, whose work space is surrounded by a miniature greenhouse of plants he has brought, said his desk has become a regular stop on the group tours. If the building is a living experiment, he said, then his garden is the experiment within the experiment. co-workers stop by, joking in geek-speak about his plants, but also seriously checking up on them as a measure of building health.
“they refer to this as the building’s carbon sink,” he said.
And Mr. Duffield’s babies—amaryllis, African violet, a pink trumpet vine—are very happy with all the refracted, reflected light they get, he said.
“the tropical trumpet vine in my house stops growing for the winter,” he said. “Here it has continued to grow, and when the days starting getting longer it might even bloom.”
Adapted from Johnson, K. (2011). Soaking Up the Sun to Squeeze Bills to Zero. new york times. Retrieved from http://www.nytimes.com/2011/02/15/science/15building.html. © 2011 The New York Times. All rights reserved. Used by permission and protected by the Copyright Laws of the United States. The printing, copying, redistribution, or retransmission of this Content without express written permission is prohibited.
Summary & Resources
chapter Summary Fossil fuels like oil, coal, and natural gas currently meet 80 percent of our energy require- ments. However, concerns about the political, economic, and environmental impacts of their use have increased interest in finding alternative energy sources. one possible approach would be to expand the use of nuclear power since this energy source emits less carbon diox- ide than fossil fuels. However, nuclear power comes with its own issues of safety, cost, waste
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storage, and the dangers of nuclear material getting into the hands of terrorists. It has been suggested that we are now in the early stages of an energy revolution or transition away from non-renewable fossil fuels, and that we are moving toward using more renewable forms of energy like solar and wind. Earlier energy transitions included the shift from wood and other forms of biomass to coal in the 19th century, as well as the rapid rise in the use of oil over the second half of the 20th century. Any significant shift from non-renewable to renewable energy sources will require changes in the way we produce and consume energy, and it will also require significant investment in new technologies and infrastructure.
this chapter began with a description of an ambitious plan to power the world with 100 per- cent renewable energy by 2030. the authors of that plan argue that while there are techni- cal and other challenges to be overcome to meet this goal, the main barrier is political. they suggest that if billions of dollars in subsidies for fossil fuels were eliminated and the external costs for these fuels were included in their price, then renewables would be highly competi- tive. However, because fossil fuel industries have enormous political clout, it might be difficult to implement policies to achieve this goal.
the chapter also made clear how important it is to improve the efficiency of energy use. If we can achieve the same outcome while using 20, 50, or even 80 percent less energy, then we can both save money and lower the environmental impact of our energy use. Achieving a signifi- cant shift from fossil fuels to renewable energy sources will be made that much easier if we are able to use energy more efficiently.
In the next chapter the focus shifts from climate change and energy to issues of pollution and waste management. the renewable energy sources described in this chapter not only have the potential to reduce greenhouse gas emissions, but they also help to address local and regional air pollution problems. Moreover, we’ll see that recycling and reuse of materials such as aluminum help to reduce the amount of energy required to produce the goods on which we depend.
Working Toward Solutions there is no one, single international body that promotes or develops all of the various forms of renewable energy, although there are a number of organizations that promote specific types. For example, the International renewable Energy Alliance (http://baringo.invotech.se/), the International Solar Energy Society (http://www.ises.org/), and the World Wind Energy Association (http://www.wwindea.org/home/index.php) all work to promote renewable energy at the international level. the International Hydropower Association (http://www .hydropower.org/) and the International geothermal Association (http://www.geothermal -energy.org/) promote these energy sources, while the International Atomic Energy Agency (http://www.iaea.org/) serves as an intergovernmental forum on issues of nuclear power development and safety.
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Working Toward Solutions (continued) globally, some countries are either more blessed with renewable energy resources or have been more aggressive in developing the renewable resources they have. World leaders in renewable energy development include germany and Denmark. Despite being far less sunny on average than the united States, germany has established itself as the number one producer of solar power in the world, producing five times as much as the u.S. (http://www.washington post.com/blogs/wonkblog/wp/2013/02/08/germany-has-five-times-as-much-solar-power -as-the-u-s-despite-alaska-levels-of-sun/). germany combines its production of solar and wind power with high levels of energy efficiency in its homes, schools, and other buildings. the germans first developed the concept of the “Passivhaus,” homes that are so energy effi- cient that they hardly require any energy for heating or cooling (http://www.passivhaustrust. org.uk/what_is_passivhaus.php). With thousands of miles of windy coastline, Denmark has emerged as one of the top wind power producers in the world and the country that gets the largest percentage of its energy needs from wind. Particularly interesting is the small island of Samso located in the geographic center of Denmark. Samso produces so much electricity from its wind turbines that it exports surplus power to the Danish mainland via underwater cables (http://www.nytimes.com/2009/09/30/world/europe/30samso.html, http://www .cbsnews.com/8301-18563_162-2549273.html, and http://www.scientificamerican.com /article.cfm?id=samso-attempts-100-percent-renewable-power). Samso has been so success- ful at achieving energy independence that the island attracts thousands of visitors every year from all over the world to learn about how they did it.
In the united States the federal government has a number of programs and policies in place to promote renewable energy and energy efficiency. For example, over the last three decades there have been at least 22 federal programs and provisions designed to boost the production and use of ethanol and biodiesel fuels, including mandates, tax incentives, and loan programs (http://www.fas.org/sgp/crs/misc/r40110.pdf). While these programs have increased the production and use of these fuels, this effort has come under criticism for being less about the promotion of renewable energy and more about providing subsidies to farmers and large agribusiness companies (http://www.fas.org/sgp/crs/misc/r40155.pdf). the national gov- ernment also provides more limited financial support to wind power, geothermal, wave/tidal power and other renewable energy sources through the Federal Production tax credit and the Investment tax credit (http://pdf.wri.org/bottom_line_renewable_energy_tax_credits _10-2010.pdf). these programs lower the tax liabilities of companies and investors who develop and deploy renewable energy facilities, lowering the cost of production and helping them be more competitive.
Besides these programs, the national renewable Energy laboratory (nrEl) of the u.S. Department of Energy (DoE) is the primary government center for research and development of renewable energy and energy efficiency (http://www.nrel.gov/). the nrEl is based in golden, colorado, and was featured in the last reading of this chapter. the Energy Star Program (http://www.energystar.gov/) was developed by the u.S. DoE and the Environmental Protec- tion Agency in the 1990s. It sets standards for energy efficiency in consumer products and appliances and advertises the energy efficiency of these products through its familiar label.
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Post-test
1. Which of the following is not one of the policy options recommended to help speed up the adoption of renewable energy technologies?
a. Implementation of a feed-in tariff b. taxing fossil fuels to reflect their externality costs c. Subsidizing corn ethanol production d. Investing in an improved long-distance power transmission system
2. It could be said that hydroelectric power is always renewable and always sustainable.
a. true b. False
3. Which of the following is not a radioactive byproduct of nuclear power production? a. cesium-137 b. Plutonium c. Strontium-90 d. Bauxite
Working Toward Solutions (continued) At a more local level, most states in the united States have developed some sort of renewable energy standard or goal. this interactive map from the center for climate and Energy Solu- tions (http://www.c2es.org/us-states-regions/policy-maps/renewable-energy-standards) shows which states have standards and provides some basic information on those programs. non-governmentally, the American Wind Energy Association (http://www.awea.org/), the American Solar Energy Society (http://www.ases.org/), and the Biomass Power Association (http://www.usabiomass.org/) all work to promote these renewable energy resources.
lastly, at an individual level, it might be difficult to imagine what one person can do to promote the development and use of renewable energy. However, these two tED talk videos tell the story of how a 14-year-old African boy built his family an electricity-generating windmill from spare parts based on a design he found in a book (http://youtu.be/g8yKFVPoD6o and http:// youtu.be/crju5hu2fag). More practically, individuals and organizations can support the devel- opment of renewable energy sources by purchasing some or all of their electricity from green power producers. this link (http://www.ucsusa.org/clean_energy/what_you_can_do/buy -green-power.html) provides some information on how individuals can do this, while this link (http://www.epa.gov/greenpower/documents/purchasing_guide_for_web.pdf) is a detailed document that organizations (such as schools, hospitals, and businesses) can make use of to decide whether and how to purchase green power. Finally, this chapter should have made clear that perhaps the most important thing individuals, organizations, and businesses can do is to first reduce their energy use through energy efficiency and conservation. this excellent guide from the Department of Energy (http://energy.gov/sites/prod/files/energy_savers.pdf ) is loaded with tips for how to reduce your energy use and save money in the process.
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4. Energy efficiency focuses more on the supply side than the demand side. a. true b. False
5. A “net-zero energy” building is designed to use no energy at all. a. true b. False
6. the authors estimate that solar power alone could produce more energy than what the world currently consumes.
a. true b. False
7. the rate of hydroelectric dam construction in the united States has been increasing steadily in recent decades.
a. true b. False
8. According to Amory lovins, the author of section 8.3, the kind of nuclear disaster that occurred in Japan in 2011 could never occur in the united States.
a. true b. False
9. Which of the following BESt explains why so many buildings are energy inefficient? a. Building codes require inefficient design. b. Builders don’t have any information on efficient design. c. consumers demand inefficient buildings. d. Builders focus more on construction costs than on life-cycle costs.
10. Energy efficiency is improved in the national renewable Energy lab building in golden, colorado, by sending real-time updates on building conditions to workers’ computers.
a. true b. False
Answers 1. c. Subsidizing corn ethanol production. the answer can be found in section 8.1. 2. b. False. the answer can be found in section 8.2. 3. d. Bauxite. the answer can be found in section 8.3. 4. b. False. the answer can be found in section 8.4. 5. b. False. the answer can be found in section 8.5. 6. a. true. the answer can be found in section 8.1. 7. b. False. the answer can be found in section 8.2. 8. b. False. the answer can be found in section 8.3. 9. d. Builders focus more on construction costs than on life-cycle costs. the answer can be found in section 8.4. 10. a. true. the answer can be found in section 8.5.
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Key Ideas
• large-scale, commercial solar and wind power facilities have the potential to meet a much larger share of our energy needs in the future. Some of the keys to making a transition from a largely fossil fuel-based economy to one powered by renewable energy such as solar and wind energy include changes to policy, better energy stor- age and distribution systems, and the removal of billions of dollars in subsidies to the fossil fuel industry.
• Hydroelectric power or hydropower is electricity generated by the force of moving water, while geothermal energy takes advantage of heat from within the Earth. Both hydropower and geothermal energy are considered traditional forms of renew- able energy since they have been in widespread use for decades or even centuries. Hydropower is a relatively clean form of energy since it does not depend on mining or combusting fossil fuels. However, construction of hydropower dams does disturb large land areas and can cause a variety of negative environmental impacts. geother- mal energy comes in a variety of forms and is also a relatively clean form of energy.
• the March 2011 earthquake and tsunami in northern Japan triggered a massive catastrophe at the Fukushima nuclear power complex. that catastrophe has reig- nited debates over nuclear power and its future development. Supporters of nuclear power argue that it is a relatively clean form of energy and that isolated disasters like the one at Fukushima should not stop further development of this technology. opponents respond that nuclear power is not nearly as clean as renewable alterna- tives, that the risks of catastrophe are unacceptable, and that nuclear can only be supported economically through massive government subsidies.
• Energy efficiency is achieving the same outcome—such as lighting or heating a room—while using less energy to do so. Energy efficiency helps reduce overall energy demand and, in the process, the environmental impacts of that energy use. While energy efficiency can reduce environmental impact and lower energy bills, there are economic and political barriers to its more widespread adoption. consum- ers might hesitate to invest in the up-front costs necessary to achieve energy effi- ciency even if it will save them money over the long term. Politically, energy effi- ciency does not attract the same attention or interest as renewable and other forms of energy.
• net-zero energy buildings are designed to produce as much energy as they con- sume. they achieve this energy self sufficiency by combining high levels of energy efficiency with on-site energy production by solar panels and other devices. the national renewable Energy laboratory building described in section 8.5 is the larg- est net-zero energy office building in the united States and was built for roughly the same cost as other commercial office buildings on a square foot basis.
critical thinking and Discussion Questions
1. Much of the gasoline sold in the united States is blended with a small amount of corn-based ethanol. While this ethanol is considered a “renewable” energy source since it comes from corn, and corn can be constantly re-grown, many energy experts are skeptical of any environmental advantage from the widespread use of ethanol (see, for example, http://e360.yale.edu/feature/the_case_against_biofuels_probing _ethanols_hidden_costs/2251/). Why might this be the case? What is it about the way we currently grow corn, and convert that corn to ethanol, that make any
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environmental benefit from this fuel minimal? Why is it that despite the potential problems with corn-based ethanol this renewable energy form continues to receive generous government subsidies while subsidies for wind and solar power have been more difficult to secure?
2. on the surface, hydropower appears to offer a number of environmental advantages over electricity produced from burning coal or other fossil fuels. In particular, since hydropower does not involve any fossil fuel combustion, it does not directly emit greenhouse gases such as carbon dioxide into the atmosphere. However, recent scien- tific research (http://www.newscientist.com/article/dn7046-hydroelectric-powers -dirty-secret-revealed.html) suggests that hydropower projects in some locations, especially tropical regions, may be responsible for significant emissions of methane, a powerful greenhouse gas. this is because large-scale hydropower projects usually involve flooding large areas of land. If those lands were forested, the trees and other vegetation now under water will decompose and release methane gas in the process. If you were a scientist tasked with estimating the methane emissions from a large- scale hydropower project before it gets built, what kind of experiment might you design to answer this question? How could you use this information to compare the relative greenhouse gas impacts of the hydropower project compared to a traditional coal-fired power plant?
3. Some people argue that the Fukushima nuclear accident in Japan was an isolated incident and that the same thing could not occur in the united States. Even if this were true (and there’s no way to know this), what are some of the other reasons many experts still oppose increased development of nuclear power?
4. one of the major barriers to greater adoption of energy efficiency approaches is that consumers don’t always take a long-term view of energy consumption and costs. consider the following examples: • a young couple with limited savings buys a “fixer-upper” house with drafty win-
dows and poor insulation. they estimate that it would cost them roughly $4,000 to replace the windows and install adequate insulation. If they did these things they could save over $1,000 a year in heating costs, recouping their investment in roughly four years.
• a retired couple on a fixed income is debating whether to replace their 20-year old refrigerator with a new, energy-efficient model that costs $1,000. They have been informed that the new refrigerator could save them $30 a month in electric bills or $360 a year, meaning they would recoup their investment in less than three years.
Both of these examples present a case where it would make sense to pursue energy efficiency and save substantial amounts of money in the long term. However, both cases also describe a situation where the energy efficiency investments probably won’t be made due to the inability to afford the “up front” or initial investments. What kind of policies or programs do you think could be used to change this situ- ation and help these couples make the right choice? How might programs like this be funded? How should they be communicated or advertised to the public?
5. the national renewable Energy laboratory net-zero energy building described in section 8.5 represents some of the best examples of “smart design” in building construction. the building is designed to allow natural light to provide most of the daytime illumination, for sunlight to provide heat in the winter and electricity throughout the year, and for its occupants to know when and how to adjust their behaviors to save energy. unfortunately, most of the buildings we live and work in
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externality cost the monetary value of health and environmental damage not factored into the price of a product such as fossil fuels.
life-cycle cost the sum of all recurring and one-time (non-recurring) costs over the full life span of a good, service, structure, or system.
light-water reactors A common nuclear reactor that uses water as a moderator and coolant.
meltdown the melting of a nuclear reactor vessel causing the release of a substantial amount of radiation into the environment.
net-zero energy A building or installation that produces as much energy as it con- sumes and is considered to be energy self- sufficient or near self-sufficient.
nuclear fission A nuclear reaction in which large atoms of certain elements are split into smaller atoms with the release of a large amount of energy.
nuclear reactor A device that initiates and maintains a controlled nuclear fission chain reaction to produce electricity.
photovoltaics Silicon-based energy cells that generate electricity when solar energy is absorbed; also called photovoltaic collectors.
principal-agent problem A situation that occurs when someone makes a decision that impacts energy consumption and the cost is passed on to another person or business.
renewable energy Energy generated from natural resources such as sunlight, wind, and water, which are naturally replenished.
wind farm A power plant made up of a col- lection of wind turbines used for generating electricity; usually located in flat, wide open places where there is a constant breeze.
wind turbine A mechanical device that uti- lizes the kinetic energy of wind by capturing it and converting it into electricity.
do not feature smart design. If anything, many of them could be characterized as “dumb design.” think about your own house or apartment, or the building in which you work or go to school. next, think about how energy is used to light, heat, cool, or provide power to devices in that building. can you find examples of smart design or dumb design? Are there features of the building that lead to unnecessary energy waste? Why do you think so many of the buildings in this country were built with so little thought or consideration for how they use energy?
Key terms
Additional resources
In addition to the links provided in this section, there is additional information on the topics covered in this chapter in the Working Toward Solutions section.
the Federal Energy regulatory commission tracks energy infrastructure projects and pub- lishes regular reports on what percentage of our new energy systems come from various sources. their 2012 report (http://www.ferc.gov/legal/staff-reports/dec-2012-energy -infrastructure.pdf) was remarkable in that it illustrated that fully one-half of all new power generating capacity installed in the united States in 2012 was based on renewable energy
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resources. this can be seen by examining the breakdown by energy source in the table at the top of page 5.
A number of reports and articles in recent years have tried to examine the possibility of achieving close to 100 percent renewable energy in the decades ahead.
• http://wwf.panda.org/what_we_do/footprint/climate_carbon_energy/energy _solutions22/renewable_energy/sustainable_energy_report/
• http://web.chem.ucsb.edu/~feldwinn/greenworks/readings/solar_grand_plan.pdf • http://www.pewtrusts.org/uploadedFiles/wwwpewtrustsorg/reports/global
_warming/g20-report-lowres.pdf • http://www.ucsusa.org/global_warming/solutions/reduce-emissions/climate
-2030-blueprint.html • http://www.ucsusa.org/assets/documents/clean_energy/ramping-up-renewables
-Energy-you-can-count-on.pdf
this very recent article by New York Times writer Elisabeth rosenthal explains why the transition to renewable energy may be happening sooner than many think (http://www.ny times.com/2013/03/24/sunday-review/life-after-oil-and-gas.html) this article illustrates how the u.S. military and the Department of Defense are already leading the way in the devel- opment of renewable energy resources for strategic reasons (http://www.motherjones.com /environment/2013/02/navy-climate-change-great-green-fleet).
the Energy Information Administration provides some useful background information on a variety of renewable energy resources, including:
• Hydroelectric power: http://www.eia.gov/energy_in_brief/article/hydropower.cfm and http://www.eia.gov/energyexplained/index.cfm?page=hydropower_home
• Wind power: http://www.eia.gov/energy_in_brief/article/wind_power.cfm and http://www.eia.gov/energyexplained/index.cfm?page=wind_home
• Biomass and biofuel energy: http://www.eia.gov/energyexplained/index.cfm? page=biomass_home and http://www.eia.gov/energyexplained/index.cfm?page =biofuel_home
• geothermal energy: http://www.eia.gov/energyexplained/index.cfm?page =geothermal_home
• Solar energy: http://www.eia.gov/energyexplained/index.cfm?page=solar_home
the online news source Yale Environment 360 provides a literal wealth of information on all kinds of issues surrounding energy. this link takes you directly to their energy section: http://e360.yale.edu/topic/energy/015/
For more information on the Fukushima nuclear disaster in Japan, you can check out:
• http://www.nature.com/news/specials/japanquake/fukushima.html • http://www.iaea.org/newscenter/news/tsunamiupdate01.html • http://energy.gov/situation-japan-updated-12513
this link provides a brief update of the status of the nuclear industry in the united States. (http://www.eia.gov/energy_in_brief/article/nuclear_industry.cfm). A somewhat supportive
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report on the future of nuclear power was published by a group out of MIt (http://web .mit.edu/nuclearpower/pdf/nuclearpower-summary.pdf), while the union of concerned Sci- entists represents a group opposed to nuclear power on safety, environmental, and economic grounds (http://www.ucsusa.org/nuclear_power/). Amory lovins expands on his argu- ments against nuclear power in a piece titled “the nuclear Illusion” (http://www.rmi.org /Knowledge-center/library/E08-01_nuclearIllusion). At the international level, this report argues that nuclear power and renewables are not really compatible, and that society should make a clear choice in favor of one path or another (http://www.boell.eu/downloads /froggatt_schneider_systems_for_change.pdf).
An interesting way to promote energy efficiency is through the use of social psychology as explained in this story from Yale Environment 360 (http://e360.yale.edu/feature/how_data _and_social_pressure_can_reduce_home_energy_use/2597/). one of the most comprehensive reports on energy efficiency in the united States was by the McKinsey global Energy and Materials group (http://www.mckinsey.com/client_service/electric_power_and_natural_gas /latest_thinking/unlocking_energy_efficiency_in_the_us_economy).
the u.S. Water Power Program helps to develop technologies to harness the power of water not only through traditional hydropower but also through waves and tides (http:// www1.eere.energy.gov/water/). tidal power and wave power are also explained in a little more detail here (http://education.nationalgeographic.com/education/encyclopedia/tidal -energy/?ar_a=1) and here (http://www.alternative-energy-news.info/technology/hydro /wave-power/). A form of biomass energy known as biogas is described in some detail here (http://www.afdc.energy.gov/fuels/emerging_biogas.html) and here (http://biogas.ifas.ufl .edu/).
lastly, here are two great sources that provide a lot of information on the problems and chal- lenges associated with our conventional energy system and the promises and possibilities for a renewable energy future (http://earththeoperatorsmanual.com/landing/watch-share) and (http://burnanenergyjournal.com/apm-station-info/).
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© Milos Peric/iStock/Thinkstock
Learning Objectives
After studying this chapter, you should be able to:
• Discuss the historical development of our scientific understanding of the greenhouse effect and cli- mate change, especially the connection between atmospheric concentrations of greenhouse gases and temperature.
• Review some of the major impacts of climate change that are predicted to occur, or are already occur- ring, including more extreme weather, changes in water supply, impacts to human health, extinction of animal species, and rising sea levels.
• Describe how climate change might impact agricultural production and food supply in various regions of the world.
• Explain the importance of the stratospheric ozone layer to life on Earth and discuss the ways in which the use of chlorofluorocarbons (CFCs) resulted in ozone depletion and the emergence of an ozone hole.
• Discuss the relationship between carbon dioxide emissions and ocean acidification and how changes to ocean chemistry could impact the productivity and biodiversity of the seas.
Global Climate Change and Ozone Depletion 7
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Pre-Test
1. the greenhouse effect is a natural phenomenon. a. true b. False 2. Major scientific assessments have determined that natural causes could be responsible
for much of the observed changes to climate in recent decades. a. true b. False 3. Food insecurity and rising food prices were major factors in the unrest and uprisings
known as the Arab Spring. a. true b. False 4. the ozone layer that protects life on Earth is located primarily in what region of the
atmosphere? a. troposphere b. Mesosphere c. Stratosphere d. Ionosphere 5. Scientific research has revealed that excess carbon dioxide emissions are making the
oceans less acidic. a. true b. False
Answers 1. a. true. the answer can be found in section 7.1. 2. b. False. the answer can be found in section 7.2. 3. a. true. the answer can be found in section 7.3. 4. c. Stratosphere. the answer can be found in section 7.4. 5. b. False. the answer can be found in section 7.5.
Introduction In 982, Erik the Red left his homeland with a small band of followers and sailed west from Iceland to establish a colony on Greenland, which was previously uninhabited by Europeans. the Vikings farmed, raised sheep, and traveled even farther north to hunt seals, walrus, and whales. the settlement flourished for about 500 years, eventually growing to 4,000 inhabit- ants. Eventually, all the colonists died out and the abandoned farms and weathered tomb- stones stood out against the arctic sky. Although there are many reasons why this tragedy occurred, experts agree that climate change played a part. From about 1450 to 1850, in a period called the “Little Ice Age,” the northern Hemisphere became unusually cold by histori- cal standards. In the Arctic colonies, this cooling trend led to crop failure and starvation, and the settlers were unable to survive.
Climate change is not a new thing, and global temperatures have gone up and down through- out the history of the Earth. However, recent warming of the planet has generated concern
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among scientists and others for at least two reasons. First, whereas past climate changes were caused by natural factors, the current warming trend is primarily the result of human activi- ties. Second, if not addressed soon, climate change has the potential to disrupt agriculture, water supply, weather patterns, and other conditions essential for our survival. As such it’s important to gain a solid understanding of what climate change is and the science behind it.
Climate change is also among the most controversial of environmental issues, and in recent years the issue has become highly politicized. In studying climate change it is important to try to keep separate the scientific study of the issue and the political implications that might fol- low from that research. the vast majority of scientists studying climate change bring no par- ticular political agenda to their work. However, because that research is increasingly pointing to the reality of climate change and a major human role in causing that change, it is sometimes dismissed as being motivated by a political agenda.
In order to keep these issues in perspective, it is helpful to consider the difference between arguments that are based on positive claims, or statements about what we know, and argu- ments based on normative claims, statements about what we value (Dessler and Parson, 2006). When a climate scientist makes a claim that atmospheric carbon dioxide concentra- tions are rising and that average global temperatures are increasing, that is a positive claim, a statement about the way things are. When a politician makes an argument that we should increase taxes on gasoline to reduce carbon dioxide emissions, that is a normative statement, an argument for the way things should be (at least in the view of that politician). Scientific research has political implications, but recall from the earlier discussion of the scientific method that this research is guided by a set of principles that keep it focused on understand- ing the way the world is. How politicians and others make use of that research to argue for the way the world should be is a separate issue from the validity and integrity of the original scientific research.
Before we begin the readings on climate change, this chapter will open with a series of ques- tions and answers, or Frequently Asked Questions (FAQs), that will lay the foundation for your understanding of this issue. the first reading will then introduce you to the history of climate change science in order to help illustrate how we came to understand what we now know about this issue. this is followed by a comprehensive review of the causes and conse- quences of climate change, a reading that will tie together and test your knowledge of the information presented in the opening FAQ section. Section 7.3 addresses one of the most wor- risome aspects of climate change, its potential impact on world food production and sup- plies. Section 7.4 shifts gears a little and introduces the issue of stratospheric ozone deple- tion. While ozone depletion and climate change are sometimes confused and thought to be the same problem, these are largely separate and unrelated issues. the final section presents a case history of how carbon dioxide emissions and global warming are impacting the world’s oceans in potentially devastating ways. Whereas this chapter is primarily focused on the global warming problem, the following chapter will introduce some possible solutions in the form of alternative energy sources. Since carbon dioxide emissions from fossil fuel combus- tions are the single greatest contributor to human-caused climate change, alternative energy sources represent one of the most important responses to this issue.
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The Basics of Climate Change—Frequently Asked Questions 1. What factors determine the Earth’s climate? our climate system is powered by solar radiation from the sun and is determined by the energy balance of incoming and outgoing energy (see Figure 7.1). About one-third of incoming, short- wave solar radiation is reflected by clouds or light surfaces on the Earth (like ice and snow) and bounced back to space. Much more of this shortwave radiation is absorbed by the Earth’s surface and then given off or re-radiated as heat energy. If you’ve ever stood barefoot on a dark surface on a sunny summer day, you’ve experienced this firsthand. Greenhouse gases such as water vapor and carbon dioxide are present naturally in the atmosphere, and they absorb and trap some of this outgoing radiation and help keep the Earth’s surface relatively warm. Learn more about this here:
• https://www.ipcc.unibe.ch/publications/wg1-ar4/faq/wg1_faq-1.1.html
Figure 7.1: Earth’s energy balance
the sun emits shortwave solar radiation onto the Earth’s surface. Some of this radiation is reflected back into space by clouds and light surfaces such as snow or ice on mountains. Most of the shortwave radiation is absorbed by the Earth’s surface and then re-radiated or released back as infrared or heat energy. Some of this heat energy is then absorbed and re-radiated back toward the Earth’s surface by greenhouse gases like carbon dioxide and water vapor.
2. What is the greenhouse effect? the two most abundant gases in the atmosphere are nitrogen and oxygen, together account- ing for roughly 99 percent of the total. these gases play almost no role in trapping or absorb- ing the outgoing heat energy coming from the Earth’s surface. Instead, other gases present in extremely small quantities in the Earth’s atmosphere absorb and re-radiate outgoing heat or longwave radiation. these gases—including water vapor, carbon dioxide, methane, and nitrous oxide—act like a blanket helping to hold heat energy close to the Earth’s surface. these gases could also be thought of as windows in a greenhouse or car, allowing sunlight to pass
(continued)
HeatHeat Heat
CO2 CO2 CO2 Water vapor
Water vaporShortwave
solar radiation
Earth’s atmosphere with greenhouse gases
IntRoDuCtIon
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The Basics of Climate Change—Frequently Asked Questions (continued)
through the atmosphere but trapping the heat that tries to escape (see Figure 7.2). Although they only make up a fraction of a percent of the composition of the atmosphere, these green- house gases are responsible for the greenhouse effect and essentially for life as we know it. It’s estimated that without greenhouse gases, the average temperature on Earth would be about 0 degrees Fahrenheit (F). Instead, the average surface temperature globally is 59 degrees F. Learn more about this here:
• https://www.ipcc.unibe.ch/publications/wg1-ar4/faq/wg1_faq-1.3.html • http://www2.sunysuffolk.edu/mandias/global_warming/greenhouse_gases.html
3. How are the greenhouse effect, global warming, and global climate change different?
the greenhouse effect is a natural phenomenon without which we might not be here. When we talk of global warming we are really referring to an enhanced greenhouse effect caused by human emissions of greenhouse gases like carbon dioxide. these human emissions, for example from burning fossil fuels, are increasing the concentration of greenhouse gases in the atmosphere and contributing to global warming. While essentially the same thing, most sci- entists prefer to use the term global climate change since warming of the Earth is also altering precipitation patterns and other factors related to climate. Learn more about this here:
• http://www.bis.gov.uk/go-science/climatescience
4. What is the difference or the relationship between climate and weather? the old saying is that “climate is what you expect, weather is what you get.” Climate can thus be explained as the average weather in a particular place over many years. Global warming or global climate change does not mean that we will no longer have cold weather. Instead, it means that on average we should expect to see less cold weather and an increase in warmer temperatures in most parts of the world, a prediction that is borne out definitively by the data. Learn more about this here:
• https://www.ipcc.unibe.ch/publications/wg1-ar4/faq/wg1_faq-1.2.html • http://www.eo.ucar.edu/basics/
5. How do human activities contribute to climate change, and are they more or less important than natural factors?
While we know that we are currently experiencing a period of warming, how can we be certain that this is a result mainly of human activities? Scientists call this a question of attribution; to what can we attribute the observed warming? Scientists start by looking at all of the differ- ent possible causes of warming and then examine whether any of them provide a plausible explanation for what we are seeing. For example, throughout the history of the planet factors like tectonic activity, volcanic eruptions, variations in the Earth’s orbit, changes in solar radia- tion, and internal variation in the Earth’s climate system (e.g., the El niño phenomenon) have contributed to climate change. However, when scientists examine all of these factors, none of them alone or in combination comes close to explaining the actual warming we are currently seeing. In contrast, the steady increase in greenhouse gas concentrations in the atmosphere
(continued)
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The Basics of Climate Change—Frequently Asked Questions (continued)
due to human activities like fossil fuel burning does explain the observed warming. therefore, climate scientists are confident in attributing current climate change largely to human factors. Learn more about this here:
• https://www.ipcc.unibe.ch/publications/wg1-ar4/faq/wg1_faq-2.1.html • http://www2.sunysuffolk.edu/mandias/global_warming/natural_causes_climate
_change.html • http://www.c2es.org/science-impacts/basics/faqs/climate-science#Causes
6. How are temperatures changing, and is it true that global warming has stopped or paused?
Measurements of surface temperatures from around the planet going back to about 1850 show a clear trend of increasing temperature over time. Furthermore, average temperatures have generally been rising at an increasing rate. However, recent claims have been made that global warming has paused and that the planet has stopped warming since the late-1990s. Such claims are a good example of how scientific data can be misrepresented to make mislead- ing and false claims. In reality, a number of factors are currently at work. First, persistent La niña conditions and an increase in volcanic activity (which puts particles into the atmosphere that block incoming sunlight) have slowed the rate of temperature increases in recent years, but 20 of the warmest years on record have occurred in the last 25 years. Second, the oceans have been warming far faster than land areas, suggesting that they are, at least temporarily, storing much of the increased heat caused by higher levels of greenhouse gases in the atmo- sphere. third, some climate skeptics have been using graphs showing trends in global tem- peratures since 1998, suggesting that temperatures have flattened out. However, 1998 was tied for the second-warmest year on record, so using that year as your starting date paints a misleading picture of the long-term trend. Learn more about this here:
• http://www.youtube.com/watch?v=r_qdEtSYcDM • http://www2.sunysuffolk.edu/mandias/global_warming/global_cooling.html • http://www2.sunysuffolk.edu/mandias/global_warming/modern_day_climate_change
.html • https://www.ipcc.unibe.ch/publications/wg1-ar4/faq/wg1_faq-3.1.html • http://svs.gsfc.nasa.gov/vis/a000000/a004000/a004030/
(continued)
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The Basics of Climate Change—Frequently Asked Questions (continued)
Figure 7.2: Greenhouse effect
the greenhouse effect derives its name from the fact that the atmosphere acts something like a greenhouse. the sun’s rays can pass through the atmosphere, which acts like glass in a greenhouse, and strike the Earth’s surface where they are converted to infrared or heat energy. However, just like the glass in a greenhouse, the various greenhouse gases help to trap some of that heat inside the structure. Adding more greenhouse gases to the atmosphere is like thickening the glass in a greenhouse, trapping more heat in and increasing the temperature.
7. Is global climate change an ethical issue? Won’t “solving” the global warming problem ruin our economy?
While the debate over climate change might appear to be mainly a scientific one, it is also one of the most important ethical issues of our time. Because climate change can lead to rising sea levels, changes in precipitation patterns, and disruptions in water supply, it could have serious impacts on our ability to grow enough food to feed ourselves. While relatively wealthier coun- tries like the united States have the resources and technology to adapt to some of these changes,
(continued)
Heat
CO2
CO2
C O
2 CO 2
CH4
CH 4
C H 4
C H
4
W ate
r va
po r
W ater
vapor
Wa ter va
po r
Water vapor
N2O
N2O
N 2O
N 2 O
At mo
sph ere
UV Radiation
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The Basics of Climate Change—Frequently Asked Questions (continued)
poorer countries are far more vulnerable and less able to adapt. Since the vast majority of the greenhouse gas emissions that are causing climate change have come from wealthy coun- tries like the united States, there is a clear ethical problem in this situation. Likewise, today’s population changing the climate for future generations poses an enormous ethical dilemma. In terms of economic impact, many of the most immediate approaches to reducing green- house gas emissions actually involve reducing energy use and saving money. Also, renewable energy sources like wind and the sun are domestic forms of energy whose development could help spur economic activity in the united States. Much of the opposition to addressing climate change has come from fossil fuel industries (especially coal and oil) that stand to see their profits reduced dramatically if any serious efforts are made to address global climate change. Learn more about this here:
• http://www.ucsusa.org/global_warming/solutions/reduce-emissions/climate-2030-blue print.html
8. What are the major impacts of global climate change? What does the future hold and what chance do we have to adapt to changing conditions?
While not all of the impacts of global climate change will be entirely negative, we are already witnessing some of the consequences of a warming world. Scientists studying the impacts of climate change typically categorize these into water supply and quality, ecosystem changes, food production, coastal flooding and erosion, and human health impacts. For example, cli- mate change is contributing to shifts in precipitation patterns and thus in water availability. While some areas get more water, others get less, and shifting human settlements and food production systems to where water is available is not really feasible on any sort of large scale. Ecosystem impacts include shifting ranges for wildlife and plants and the possible extinc- tion of as many as one-third of all species on the planet. More erratic weather and shifting precipitation patterns could disrupt food production in many areas, especially for some of the poorest and most vulnerable people on the planet (see section 7.3). Sea level rise from warmer oceans and melting ice is already resulting in increased floods and coastal erosion in low-lying areas home to tens of millions of people around the world. Finally, negative impacts on human health include increased heat stress, increased malnutrition from crop failures, and the spread of diseases into new areas. While adaptation is possible in some cases, the ability to adapt is often a function of wealth and technological capacity. It is the poorest and most vulnerable populations on the planet who are least responsible for global climate change but who will feel the worst consequences of this phenomenon. Learn more about this here:
• http://www2.sunysuffolk.edu/mandias/global_warming/impact_climate_change.html • http://changingclimates.colostate.edu/docs/BellCurveAveragesExtremes.pdf • http://www.climatehotmap.org • http://extremeicesurvey.org
IntRoDuCtIon
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SECtIon 7.1A BRIEF HIStoRY oF tHE CLIMAtE CHAnGE DEBAtE
7.1 A Brief History of the Climate Change Debate Most people would assume that concern over global warming or global climate change was a fairly recent phenomenon. However, as this brief article by Stephan Harding of Schumacher Col- lege in England points out, scientists as far back as the 1820s took note of possible links between human activities and the climate system.
These scientists developed a basic understanding of what is known as the greenhouse effect, which will be described in more detail in the next section. At a basic level, the greenhouse effect involves certain gases that are naturally present in the atmosphere that trap infrared or heat energy as it escapes from the Earth’s surface. In essence, these gases act like the glass panes on a greenhouse. They allow sunlight in but block heat from escaping, which results in warmer temperatures. The greenhouse effect is a natural phenomenon. In fact, without it, the Earth’s average surface temperature would be a frigid 0 degrees Fahrenheit (°F) rather than its actual average temperature of around 59 °F.
What got the attention of the scientists discussed in this article were the increased concentrations of greenhouse gases in the atmosphere due to human activities. In particular, the burning of fossil fuels such as coal and oil, which releases carbon dioxide (CO2), the most common of the green- house gases after water vapor. The scientists hypothesized that adding more CO2 to the atmo- sphere could increase global temperatures and change climate. It was not until decades later, however, that scientific instrumentation advanced enough to determine that, in fact, atmospheric CO2 concentrations were increasing and that this was due almost entirely to human activities.
Today it is widely acknowledged that global average temperatures have increased since the Industrial Revolution and the widespread use of fossil fuels. However, scientists do not accept the simple presence of a correlation (higher CO2 concentrations and higher temperatures) as proof of a cause-effect relationship. Instead, other possible causes of increased temperatures (such as variations in solar energy output from the sun) also must be considered. Scientists refer to this as the issue of attribution, or to what can the observed temperature increases be attributed. Although there is still some debate over the attribution issue, there is a solid consensus that increased CO2 concentrations, due mainly to fossil fuel combustion, are primarily responsible for the observed increase in global temperatures in recent decades.
This reading helps us understand the historical basis for our current understanding of climate change. The next section will explore in more detail the actual causes and consequences of cli- mate change. Sections 7.3 and 7.5 will examine two of the most troubling impacts of our green- house gas emissions and climate change: food supply disruptions and changes to the health of our oceans.
By Stephan Harding our understanding of climate change began with intense debates amongst 19th century sci- entists about whether northern Europe had been covered by ice thousands of years ago. In the 1820s Jean Baptiste Joseph Fourier [a French mathematician and physicist] discovered that “greenhouse gasses” trap heat radiated from the Earth’s surface after it has absorbed energy from the sun. In 1859 John tyndall [a British physicist] suggested that ice ages were caused by a decrease in the amount of atmospheric carbon dioxide. In 1896 Svente Arrhenius [a Swedish physicist and chemist] showed that doubling the carbon dioxide content of the air would gradually raise global temperatures by 5–6 °C—a remarkably prescient result that was virtually ignored by scientists obsessed with explaining the ice ages.
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the idea of global warming languished until 1938, when Guy S Callender [a British engi- neer and inventor] suggested that the warming trend revealed in the 19th century had been caused by a 10% increase in atmospheric carbon dioxide from the burning of fossil fuels. At this point scientists were not alarmed, as they were confident that most of the carbon dioxide emitted by humans had dissolved safely in the oceans. However, this notion was dispelled in 1957 by Hans Suess [an Austrian physical chemist and nuclear physicist] and Roger Revelle [an American oceanographer], who discovered a complex chemical buffering system which prevents sea water from holding on to much atmospheric carbon dioxide.
the possibility that humans could contribute to global warming was now being taken seri- ously by scientists, and by the early 1960s some had begun to raise the spectre of severe climate change within a century. they had started to collect evidence to test the idea that global temperatures were increasing alongside greenhouse gas emissions, and to construct mathematical models to predict future climates.
In 1958 Charles Keeling [an American geochemist and oceanographer] began long-term mea- surements of atmospheric carbon dioxide at the Mauna Loa observatory in Hawaii. Looked at now, the figures show an indisputable annual increase, with roughly 30% more of the gas relative to pre-industrial levels in today’s atmosphere—higher than at any time in the last 700,000 years. temperature readings reveal an average warming of 0.5–0.6 °C over the last 150 years.
Figure 7.3: Atmospheric CO2 concentration at Mauna Loa
Graph shows the mean Co2 concentration at the Mauna Loa observatory from 1959 to 2012.
Based on data from U.S. Department of Commerce, National Oceanic & Atmospheric Administration. Retrieved from ftp://ftp.cmdl .noaa.gov/ccg/co2/trends/co2_annmean_mlo.txt.
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Climate change sceptics have pointed out that these records could have been due to creep- ing urbanisation around weather stations, but it is now widely accepted that this ‘urban heat island effect’ is relatively unimportant and that it doesn’t explain why most of the warming has been detected far away from cities, over the oceans and the poles.
The Case for Global Warming Since the 1960s, evidence of global warming has continued to accumulate. In 1998 Michael Mann [professor and director of the Earth System Science Center at Penn State university] and colleagues published a detailed analysis of global average temperature over the last mil- lennium known as the “hockey stick graph”, revealing a rapid temperature increase since the industrial revolution. Despite concerted efforts to find fault with Mann’s methodology, his basic result is now accepted as sound. then, in 2005, just as the Kyoto Protocol for limiting greenhouse gas emissions was ratified, James Hansen [head of the nASA Goddard Institute for Space Studies] and his team detected a dramatic warming of the world’s oceans—just as expected in a warming world.
there is now little doubt that the temperature increase over the last 150 years is real, but debate still surrounds the causes. We know that the warming during the first half of the last century was almost certainly due to a more vigorous output of solar energy, and some sci- entists have suggested that increased solar activity and greater volcanic emissions of car- bon dioxide are responsible for all of the increase. But others point out that during the last 50 years the sun and volcanoes have been less active and could not have caused the warming over that period.
By 2005 a widespread scientific consensus had emerged that serious, large-scale disruption could occur around 2050, once average global temperature increase exceeds about 2 °C, lead- ing to abrupt and irreversible changes. these include the melting of a large proportion of the Greenland ice cap (now already under way), the reconfiguration of the global oceanic circula- tion, the disappearance of the Amazon forest, the emission of methane from permafrost and undersea methane hydrates, and the release of carbon dioxide from soils.
this new theory of “abrupt climate change” has overturned earlier predictions of gradual change and has prompted some scientists to warn that unmitigated climate change could lead to the complete collapse of civilisation. Fears have been fuelled by the possibility that smoke, hazes and particles from burning vegetation and fossil fuels could be masking global warming by bouncing solar energy back to space. this “global dimming” effect is diminishing as we clean up air pollution. As a result global average temperature could rise by as much as 10 degrees Cel- sius [approximately 18 °F] by the close of the century—a catastrophic increase.
A more conservative assessment by the Intergovernmental Panel on Climate Change (IPCC) in 2001 indicated that with unabated carbon emissions, global temperature could rise gradually to
Consider This What tools and techniques might climate scientists use to predict how Earth’s cli- mate could change over time in response to increased carbon dioxide levels? How might a better understanding of past cli- mate conditions help them better predict the future?
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around 5.8 °C [roughly 10 °F] by 2100. An increase of this nature would still threaten the lives of millions of people, particularly in the global south, due to sea level rise and extreme weather events.
Although some people still deny that climate change is a problem we can do something about, last year the uK government indicated that it was on board. the Stern Review showed that without immediate and relatively inexpensive action, climate change would lead to severe and permanent global economic depression by 2050. there is now a strong scientific and economic consensus about the severity of the climate crisis.
Adapted from Harding, S. (2007, January 8). The Long Road to Enlightenment. the Guardian. Retrieved from http://www.guardian.co.uk/environment/2007/jan/08/climatechange.climatechangeenvironment/print Copy- right Guardian News & Media Ltd 2013. Used by permission.
7.2 Global Climate Change—Causes and Consequences The majority of scientific research conducted on environmental issues like climate change is often highly specific to a particular aspect of the problem. For example, one group of scientists might study whether soot particles from burning coal block incoming sunlight or absorb it, and another group might look at how oceans respond to higher concentrations of CO2 in the atmo- sphere. Due to the sheer scale of the global climate system, understanding how all the pieces fit together requires the effort of larger assessment or research bodies. The reading below from the Pew Center on Global Climate Change presents some of the summary findings of two such bod- ies, the Intergovernmental Panel on Climate Change (IPCC) and the U.S. Global Change Research Program (USGCRP). The work of the IPCC is sponsored by the United Nations and is focused on reviewing, assessing, and synthesizing current scientific research on climate change. The USGCRP coordinates federal research on climate change in the United States.
The big picture summaries provided by the IPCC and the USGCRP suggest that the Earth is warming and that human activities are very likely (over 95 percent confidence) the primary cause of this warming. While these groups acknowledge that our climate system is subject to natural variations, they conclude that recent climate change is too rapid and outside the range of what we could expect from just natural causes. Furthermore, the article argues that none of the known causes of natural climate change are able to explain the observed changes of recent decades. In contrast, the well-understood connection between greenhouse gas concentrations and temperature, known as the greenhouse effect, can explain these changes.
In this case, though, we are experiencing an enhanced greenhouse effect where human activities are pushing greenhouse gas concentrations to levels not seen for hundreds of thousands of years. The main greenhouse gases of concern are carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). Atmospheric concentrations of CO2 are now over 40 percent higher than what they were before the Industrial Revolution began, and corresponding increases for CH4 and N2O are 148 percent and 18 percent, respectively. Because these gases have the ability to absorb and re-radiate infrared energy from the Earth’s surface, research indicates that higher concentra- tions would certainly provide one plausible explanation for observed increases in temperature.
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In addition to providing an overview and explanation of the possible causes of global climate change, the following article examines some possible consequences. It makes clear that most scientists studying this issue prefer the term “global climate change” over “global warming” because it is not just global temperatures but also broader climatic factors such as rain and wind patterns that are being affected. Predicting precise impacts of climate change on small spatial scales is fraught with difficulties, but some expected impacts of climate change are already being observed. For example, the next section (7.3) will focus on climate change impacts on agricul- ture. The scientific assessment work summarized in this section represents the consensus view of well over 95 percent of the world’s leading climate experts and is probably as close as one could come to anything like a scientific consensus on the issue.
By The Center for Climate and Energy Solutions A study released by the u.S. national Academy of Sciences in 2010 said, “Climate change is occurring, is caused largely by human activities, and poses significant risks for—and in many cases is already affecting—a broad range of human and natural systems.” the climate will continue to change for decades as a result of past human activities, but scientists say that the worst impacts can still be avoided if action is taken soon.
Global Temperatures: The Earth Is Warming Global average temperature data based on reliable thermometer measurements are available back to 1880. over the last century, the global average temperatures rose by almost 1.5 °F, and the Arctic warmed about twice as much.
Based on data from the u.S. national Cli- matic Data Center, the 27 warmest years since 1880 all occurred in the 30 years from 1980 to 2009; the warmest year was 2005 followed closely by 1998.
over the past 50 years, the data on extreme temperatures have shown simi- lar trends of rising temperatures: cold days, cold nights, and frosts occurred less frequently over time, while hot days, hot nights, and heat waves occurred more frequently.
Warming has not been limited to the earth’s surface; the oceans have absorbed most of the heat that has been added to the climate system, resulting in a persistent rise in ocean tem- peratures. over time, the heat already absorbed by the ocean will be released back to the atmosphere, causing an additional 1 °F of surface warming; in other words, some additional atmospheric warming is already “in the pipeline.”
Consider This note that in discussing climate change, scientists are measuring global average temperature. How does climate differ from weather? How are they related? Does a par- ticularly hot or cold spell in one location tell us much about climate change? What if we observe large increases in hot or cold spells over a much larger geographic area?
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Greenhouse Gases: Making the Connection Although global temperatures have varied naturally over thousands of years, scientists study- ing the climate system say that natural variability alone cannot account for the rapid rise in global temperatures during recent decades. Human activities cause climate change by adding carbon dioxide (Co2) and certain other heat-trapping gases to the atmosphere. When sunlight reaches the earth’s surface, it can be reflected (especially by bright surfaces like snow) or absorbed (especially by dark surfaces like open water or tree tops). Absorbed sunlight warms the surface and is released back into the atmosphere as heat. Certain gases trap this heat in the atmosphere, warming the Earth’s surface. this warming is known as the greenhouse effect and the heat-trapping gases are known as greenhouse gases (GHGs).
Co2, methane (CH4), and nitrous oxide (n2o) are GHGs that both occur naturally and also are released by human activities. Before human activities began to emit these gases in recent centuries, their natural occurrence resulted in a natural greenhouse effect. Without the natural greenhouse effect, the earth’s surface would be nearly 60 °F colder on average, well below freezing. However, humans are currently adding to the naturally occurring GHGs in the atmosphere, causing more warming than occurs naturally. Scientists often call this
human-magnified greenhouse effect the “enhanced greenhouse effect.”
Evidence from many scientific studies confirms that the enhanced greenhouse effect is occurring. For example, scientists working at nASA’s Goddard Institute for Space Studies found more energy from the sun is being absorbed than is being emitted back to space. this energy imbal- ance is direct evidence for the enhanced greenhouse effect.
Greenhouse Gas Levels Rising In 2009, the u.S. Global Change Research Program (uSGCRP) released the most up-to-date and comprehensive report currently available about the impacts of climate change in the united States. the report says that average global concen- trations of the three main greenhouse gases—Co2, CH4, and n2o—are rising because of human activities. Since pre- industrial times, Co2 has increased by 40 percent, CH4 by 148 percent, and n2o by 18 percent.
Co2 is the principal gas contributing to the enhanced greenhouse effect. Many human activities produce Co2; the burn- ing of coal, oil, and natural gas account
© Craig Hanson/iStock/Thinkstock
Three main greenhouse gases—CO2, CH4, and N2O—are rising because of human activities such as the burning of coal, oil, and natural gas. Resulting pollution is visible above Shanghai, China.
Consider This What is the difference between the green- house effect and the enhanced greenhouse effect? Why might one be considered “good” while the other is viewed more as a problem?
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for about 80 percent of human-caused Co2 emissions. Most of the remaining 20 percent comes from changes in the land surface, primarily deforestation. trees, like all living organ- isms, are made mostly of carbon; when forests are burned to clear land, the carbon in the trees is released as Co2.
the uSGCRP report says that the current trajectory of rising GHG concentrations is push- ing the climate into uncharted territory. Co2 levels are much higher today than at any other time in at least 800,000 years. through all those millennia, there has been a clear correla- tion between Co2 concentrations and global temperatures, adding geological support for the strong connection between changes in the strength of the greenhouse effect and the earth’s surface temperature.
Scientists are certain that the burning of fossil fuels is the main source of the recent spike in C in the atmosphere. Multiple, independent lines of evidence clearly link human actions to increased GHG concentrations. Moreover, there is strong evidence that this human-induced rise in atmospheric GHGs is the main reason that the Earth has been warming in recent decades. the uSGCRP report says, “the global warming of the past 50 years is due primarily to human-induced increases in heat-trapping gases. Human fingerprints also have been iden- tified in many other aspects of the climate system, including changes in ocean heat content, precipitation, atmospheric moisture, and Arctic sea ice.” the u.S. national Academy of Sci- ences draws the same conclusion: “Many lines of evidence support the conclusion that most of the observed warming since the start of the 20th century, and especially the last several decades, can be attributed to human activities.”
Looking Ahead the more GHGs humans release into the atmosphere, the stronger the enhanced greenhouse effect will become. Scenarios in which GHGs continue to be added to the atmosphere by human activities could cause additional warming of 2 to 11.5 °F over the next century, depending on how much more GHGs are emitted and how strongly the climate system responds to them. Although the range of uncertainty for future temperatures is large, even the lower end of the range is likely to have many undesirable effects on natural and human systems.
Land areas warm more rapidly than oceans, and higher latitudes warm more quickly than lower latitudes. therefore, regional temperature increases may be greater or less than global averages, depending on location. For example, the united States is projected to experience more warming than average, and the Arctic is expected to experience the most warming.
the future climate depends largely on the actions taken in the next few decades to reduce and eventually eliminate human-induced Co2 emissions. In 2005, the u.S. national Academy of Sciences joined with 10 other science academies from around the world in a statement calling on world leaders to take “prompt action” on climate change. the statement was explicit about our ability to limit climate change: “Action taken now to reduce significantly the build-up of greenhouse gases in the atmosphere will lessen the magnitude and rate of climate change.”
Changing Climate: Theory to Reality Although “climate change” and “global warming” are often used interchangeably, rising temperatures are just one aspect of climate change. to understand why, it is important to
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distinguish between “weather” and “climate.” the climate is the average weather over a long period of time. A simple way to think of this is: weather is what determines if you will use an umbrella today; climate determines whether you own an umbrella. thus, when looking at climate change and its impacts, it is important to consider more than just global temperature trends. Changes in the climate other than average temperatures have more direct impacts on nature and society.
the uSGCRP report says, “Climate changes are underway in the united States and are pro- jected to grow,” and “Widespread climate-related impacts are occurring now and are expected to increase.” Sea level rise, the loss of sea ice, changes in weather patterns, more drought and heavy rainfall, and changes in river flows are among the documented changes in the united States. Climate change also threatens ecosystems and public health.
Dr. Jane Lubchencko, the Administrator of the national Atmospheric and oceanographic Administration, has said, “Climate change is happening now and it’s happening in our own backyards and it affects the kinds of things people care about.”
More Extreme Weather Extreme weather events have become more common in recent years, and this trend will con- tinue in the future. Climate change has a significant effect on local weather patterns and, in turn, these changes can have serious impacts on human societies and the natural world.
Stronger Hurricanes Scientists have confirmed that hurricanes are becoming more intense. Since hurricanes draw their strength from the heat in ocean surface waters, hurricanes have the potential to become more powerful as the water warms. A recent peer-reviewed assessment of the link between hurricanes and climate change concluded that “higher resolution modeling studies typically project substantial increases in the frequency of the most intense cyclones, and increases of the order of 20% in the precipitation rate within 100 km of the storm centre.”
this trend toward stronger hurricanes is noteworthy because of the vulnerability of coastal communities to these extreme events. the uSGCRP report says, “Sea-level rise and storm surge place many u.S. coastal areas at increasing risk of erosion and flooding [. . .] Energy and transportation infrastructure and other property in coastal areas are very likely to be adversely affected.” In recent years the massive destruction caused by Hurricane Katrina in the united States and by Cyclone nargis, which devastated Burma in 2008, provide painful reminders of this vulnerability.
Hotter, Wetter Extremes Average temperatures are rising, but extreme temperatures are rising even more: in recent decades, hot days and nights have grown more frequent and cold days and nights less fre- quent. there have been more frequent heat waves and hotter high temperature extremes.
In the united States, the uSGCRP report says, “Many types of extreme weather events, such as heat waves and regional droughts, have become more frequent and intense during the past 40 to 50 years.” More rain is falling in extreme events now compared to 50 years ago, resulting in more frequent flash flooding. In 1994 and 2008, the u.S. Midwest experienced
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flooding so severe that each event was considered a 500-year flood—a level of flooding so rare that it would not be expected to occur more than once in five centuries! In May 2010, the city of nashville, tennessee, experienced the worst flooding in its history, enduring what the u.S. Army Corps of Engineers declared a 1,000-year flood. nearly the entire central city was underwater for the first time. The Tennessean—nashville’s principal daily newspaper— reported that the flood cost the city a year’s worth of economic productivity. Individually, these events might be random occurrences, but they are part of a clear, long-term trend of increasing very heavy rainfall in the united States over the past 50 years.
In 2003, Europe experienced a heatwave so hot and so long that scientists estimated that such an extreme event had not occurred there in at least 500 years. that heat wave caused more than 30,000 excess deaths throughout southern and central Europe. A similarly historic heat wave struck Russia and other parts of Eastern Europe in the summer of 2010, killing thou- sands of people and destroying a large fraction of Russia’s wheat crop. Since Russia is a large grain exporter, its crop losses drove up food prices globally.
Although there is no way to determine whether an individual weather event was caused by human-induced climate change, the types of events discussed here are the types of events that scientists have predicted will become more common in a warmer climate. therefore, the events that actually occur are useful indicators of our vulnerabilities to project impacts and can teach us about the likely effects of climate change on our lives.
Too Much or Too Little: Effects on Water Climate change will alter the quantity and quality of available fresh water and increase the frequency and duration of floods, droughts, and heavy precipitation events. Although climate change will affect different regions in different ways, it is generally expected that dry regions of the world will get drier and wet regions will get wetter.
More Floods and Droughts A number of factors are expected to contribute to more frequent floods. More frequent heavy rain events will result in more flooding. Coastal regions will also be at risk from sea level rise and increased storm intensity. While some regions will suffer from having too much water, others will suffer from having too little. Diminished water resources are expected in semi- arid regions, like the western united States, where water shortages often already pose chal- lenges. Areas affected by drought are also expected to increase. As the atmosphere becomes warmer, it can hold more water, increasing the length of time between rain events and the amount of rainfall in an individual event. As a result, areas where the average annual rainfall increases may also experience more frequent and longer droughts.
Altered Availability and Quality Warmer temperatures threaten the water supplies of hundreds of millions of people who depend on water from the seasonal melting of mountain ice and snow in several ways: by increasing the amount of seasonal melt from glaciers and snowpack, by increasing the amount of precipitation that falls as rain instead of snow, and by altering the timing of snowmelt. In the near term, the melting of mountain ice and snow may cause flooding; in the long term, the loss of these frozen water reserves will significantly reduce the water available for humans, agriculture, and energy production. Earlier snowmelt brings other impacts. Western states
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have experienced a six-fold increase in the amount of land burned by wildfires over the past three decades because snowmelt has occurred earlier and summers are longer and drier.
Climate change will affect the quality of drinking water and impact public health. As sea level rises, saltwater will infiltrate coastal freshwater resources. Flooding and heavy rainfall may overwhelm local water infrastructure and increase the level of sediment and contaminants in the water supply. Increased rainfall could also wash more agricultural fertilizer and municipal sewage into coastal waters, creating more low-oxygen “dead zones” in the Chesapeake Bay and the Gulf of Mexico.
Effects on Human Health Climate change is expected to affect human health directly—from heat waves, floods, and storms—and indirectly—by increasing smog and ozone in cities, contributing to the spread of infectious diseases, and reducing the availability and quality of food and water. the uSGCRP report says that children, the elderly, and the poor are at the greatest risk of negative health impacts in the united States.
the u.S. Centers for Disease Control and Prevention have identified a number of health effects associated with climate change, including an increase in heat-related illnesses and deaths from more frequent heat waves, a rise in asthma and other respiratory illnesses due to increased air pollution, higher rates of food- and water-related diseases, and an increase in the direct and indirect impacts of extreme weather events, like hurricanes.
Threats to Ecosystems Climate change is threatening ecosystems around the world, affecting plants and animals on land, in oceans, and in freshwater lakes and rivers. Some ecosystems are especially at risk, including the Arctic and sub-Arctic because they are sensitive to temperature and likely to experience the greatest amount of warming; coral reefs because they are sensitive to high water temperatures and ocean acidity, both of which are rising with atmospheric Co2 lev- els; and tropical rainforests because they are sensitive to small changes in temperature and precipitation.
Clear evidence exists that the recent warming trend is already affecting ecosystems. Entire ecosystems are shifting toward the poles and to higher altitudes. this poses unique chal- lenges to species that already live at the poles, like polar bears, as well as mountain-dwelling species already living at high altitudes. Spring events, like the budding of leaves and migra- tion of birds, are occurring earlier in the year. Different species are responding at different rates and in different ways, which has caused some species to get out of sync with their food sources. the risks to species increase with increasing temperatures; scientists say that an additional 2 °F of warming will increase the risk of extinction for up to 30 percent of species.
Shrinking Arctic Sea Ice Arctic sea ice has seen dramatic declines in recent years. In 2007, Arctic sea ice shrank to its smallest summertime extent ever observed, opening the northwest Passage for the first time in human memory. this new sea ice minimum came only a few months after a study reported that since the 1950s, summer sea ice extents have declined three times faster than projected
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by climate models. In the summer of 2010, Arctic sea ice set a new kind of record: It decreased to the lowest volume ever observed. While the extent (the area of the Arctic ocean covered by ice) in 2010 was slightly higher than in 2007, the ice was considerably thinner in 2010, mak- ing the volume lower than in 2007. Scientists are concerned that this historically low volume of ice could be more susceptible to melting in the future, causing sea ice loss to accelerate.
the importance of sea ice decline comes from the role it plays in both the climate system and large Arctic ecosystems. Snow and ice reflect sunlight very effectively, while open water tends to absorb it. As sea ice melts, the earth’s surface will reflect less light and absorb more. Conse- quently, the disappearance of Arctic ice will actually intensify climate change.
Moreover, as the edge of the sea ice retreats farther from land during the summer, many marine animals that depend on the sea ice, including seals, polar bears, and fish, will lose access to their feeding grounds for longer periods. Eventually, this shift will deprive these organisms of their food sources and their populations will not be sustained.
If warming continues, scientists are sure that the Arctic ocean will become largely free of ice during the summer. Depending in part on the rate of future greenhouse gas emissions, the latest model projec- tions indicate that the opening of the Arc- tic is likely to occur sometime between the 2030s and 2080s. the opening of the Arctic has enormous implications, ranging from global climate disruption to national security issues to dramatic ecological shifts. the Arctic may seem far removed from our daily lives, but changes there are likely to have serious global implications.
Apply Your Knowledge the consequences of abrupt climate change have become so worrisome that some scientists, politicians, and even environmentalists have begun to call for more research into a technique known as geoengineering to help address the problem. Geoengineering is the deliberate intervention and modification of Earth systems to prevent or reduce climate change. For example, some clouds can reflect incoming sunlight, and so one geoengineering scheme is designed to increase the number of clouds in the sky to help cool the planet. the debate over geoengineering is focused on a number of questions:
• Is this a practical and realistic way to address climate change? • Could geoengineering schemes solve one issue (climate change) while triggering other,
potentially more serious problems? • Wouldn’t it be better and more direct to address the root causes of climate change—
greenhouse gas emissions—than to pursue geoengineering?
Consider This Based on what you know about how the greenhouse effect works, why does con- verting a surface of ice and snow to open water lead to a further intensification of climate change? Scientists call this a feed- back effect; why do you think they chose this term?
(continued)
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Rising Sea Level Among the most serious and potentially catastrophic effects of climate change is sea level rise, which is caused by a combination of the “thermal expansion” of ocean water as it warms and the melting of land-based ice. to date, most climate-related sea level rise can be attributed to thermal expansion. Going forward, however, the largest potential source of sea level rise comes from melting land-based ice, which adds water to the oceans. By the end of the century, if nothing is done to rein in GHG emissions, global sea level could be three to six feet higher than it is today, depending on how much land-based ice melts. Moreover, if one of the polar ice sheets on Greenland or West Antarctica becomes unstable because of too much warming, sea level is likely to continue to rise for more than a thousand years and could rise by 20 feet or more, which would permanently flood virtually all of America’s major coastal cities.
Even small amounts of sea level rise will have severe impacts in many low-lying coastal com- munities throughout the world, especially when storm surges are added on top of sea level rise. High population densities and low elevations make some regions especially vulnerable, including Bangladesh and the nile River Delta in Egypt. In the united States, about half of the population lives near the coast. the most vulnerable areas are the Mid-Atlantic and Gulf Coasts, especially the Mississippi Delta. Also at risk are low-lying areas and bays, such as north Carolina’s outer Banks, much of the Florida Coast, and California’s San Francisco Bay and Sacramento/San Joaquin Delta.
Loss of Glaciers, Ice Sheets, and Snow Pack Land-based snow and ice cover are declining because of climate change and contributing to sea level rise. Mountain glaciers at all latitudes are in retreat, from the Himalayas in Central
Apply Your Knowledge (continued) First, review the following sources of information on geoengineering:
• A Discovery news article on how the debate over geoengineering is splitting the scien- tific community: http://news.discovery.com/earth/global-warming/geoengineering -climate-change-121021.htm
• Web pages for Geoengineering Watch and the oxford Geoengineering Programme that provide detailed information on this concept: http://www.geoengineeringwatch.org/ and http://www.geoengineering.ox.ac.uk/
• An article from Nature magazine on geoengineering and environmental ethics: http://www.nature.com/scitable/knowledge/library/geoengineering-and -environmental-ethics-80061230
After reviewing this material, what is your assessment of geoengineering as a potential solu- tion to the challenge of climate change? If you were a scientist interested in the possible costs and benefits of geoengineering, what kind of research would you want to conduct to help bet- ter inform decisions about this approach? Pick one specific example of a geoengineering tech- nique and design a scientific experiment to assess both its possible effectiveness and potential problems.
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Asia to the Andes in tropical South America to the Rockies and Sierras in the western united States. As a conse- quence of warming, many mountain glaciers will be gone by mid-century; Glacier national Park, for example, will likely lose its glaciers by 2030.
the polar ice sheets on Greenland and Antarctica have both experienced net losses of ice in recent years. Melting polar ice sheets add billions of tons of water to the oceans each year. Recent peer-reviewed research found that the Greenland Ice Sheet is losing ice twice as fast as scientists had previously estimated and ice loss has accelerated on both Greenland and Antarctica over the past decades.
Antarctica is losing ice to the melt- ing and slipping of glacier ice into the ocean at a rate enhanced by climate change. Scientists who study the ice sheet fear that the loss of ice could be accelerated by rising sea levels and the warming of ocean water around the fringe of the ice sheet, which rests on the seabed around the coast of West Antarctica. Beyond some threshold amount of warming, the ice sheet could become unstable and ongoing rapid sea level rise could then be unstop- pable. not knowing exactly what level of warming would destabilize this ice sheet calls for caution in how much more warming we allow.
What Can Be Done the GHGs that are already in the atmosphere because of human activity will continue to warm the planet for decades to come. In other words, some level of continued climate change is inevitable, which means humanity is going to have to take action to adapt to a warming world. However, it is still possible—and necessary—to reduce the magnitude of climate change. A growing body of scientific research has clarified that climate change is already underway and some dangerous impacts have occurred. Avoiding much more severe impacts in the future requires large reductions in human-induced Co2 emissions in the coming decades. Conse- quently, many governments have committed to reduce their countries’ emissions by between 50 and 85 percent below 2000 levels by 2050. Global emissions reductions on this scale will
Lisi Niesner/Reuters/Corbis
© Ashley Cooper/Corbis
Evidence of global warming is clearly visible in the rapid disappearance of mountain glaciers over just a few decades, such as the Pasterze Glacier in Austria (top) or the Athabasca glacier in Canada (bottom). The signs in the photos mark the position of the glaciers in 1980 and 1942, respectively.
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reduce the costs of damages and of adaptation, and will dramatically reduce the probability of catastrophic outcomes.
Adapted from Global Warming and Global Climate Change, Center for Climate and Energy Solutions. 2011. Climate Change 101: Science and Impacts. Available online at: http://www.c2es.org/science-impacts/climate-change-101. Used by permission of the Center for Climate and Energy Solutions, www.c2es.org.
Apply Your Knowledge the u.S. Environmental Protection Agency (EPA) has begun to track industrial and energy facilities that emit large quantities of greenhouse gases (GHGs) into the atmosphere. the EPA Greenhouse Gas Reporting Program web page provides detailed information on GHG emis- sions from nine types of industries. For this assignment, follow these steps:
1. Visit the program web page here: http://www.epa.gov/ghgreporting/ 2. Click on the GHG Data Publication tool (click the map). 3. Choose your state from the “view facilities in your state” drop-down list. 4. Zoom into an area near where you live to see if there are any major emitting facilities in
that region. 5. Change the “data view” selection in the upper right corner to view your state data as a
list, as a bar chart, or as a pie chart. 6. Lastly, choose your county or other counties from the “Browse to a County” drop-down
list and see how emissions vary by industry type at the local level.
once you’ve spent some time exploring this site and examining the available data, consider these questions:
• How many large emitting facilities are located in your area? Did you know of their pres- ence before this?
• Which industry type was most responsible for greenhouse gas emissions in your area? Is that what you would expect, or were you surprised by these results?
• How might the data available on this site be useful to scientists and others working to understand greenhouse gas emissions and their connection to climate change?
7.3 Climate Change and World Food Supplies Chapters 2, 3, 4, and 5 helped lay the foundation for a better understanding of how population growth, agricultural practices, land use, and water management all contribute to environmen- tal and social change. In a world where population could reach 9, 10, or 11 billion later this century, it will already be a challenge to meet global food demand. Add to that the fact that current approaches to agriculture, land use, and water management are actually undermining the productivity of our food system, and we have an enormous challenge on our hands. To make matters even worse, climate change is already altering precipitation patterns and changing conditions for farming in many regions of the world. We could think of this as a “perfect storm” of population growth, environmental degradation, and climate change all coming together to threaten our ability to feed the world in the decades ahead.
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This article by John Vidal of the British media outlet the observer reviews some of the current and projected impacts of climate change on food supplies on a region-by-region basis. It demon- strates that while not all of the changes will be negative, the overall impact on agriculture and food supplies of a changing climate will be for the worse. This is especially true of the impacts of climate change on food production systems in some of the poorest regions of the world. While humans have been able to adapt to climate changes in the past, the rate of current change that we are already seeing combined with a much larger population suggests that adaptation has its limits. What is needed is a more aggressive global effort to address the major causes of climate change (see Chapter 8) and simultaneous investment in improving the productivity and resil- iency of food production systems in poorer regions of the world.
By John Vidal When the tunisian street vendor, Mohamed Bouazizi, set himself on fire on 17 December 2010, it was in protest at heavy-handed treatment and harassment in the province where he lived. But a host of new studies suggest that a major factor in the subsequent uprisings, which became known as the Arab spring, was food insecurity.
Drought, rocketing bread prices, food and water shortages have all blighted parts of the Mid- dle East. Analysts at the Centre for American Progress in Washington say a combination of food shortages and other environmental factors exacerbated the already tense politics of the region. As the Observer reports today, an as-yet unpublished uS government study indicates that the world needs to prepare for much more of the same, as food prices spiral and long- standing agricultural practices are disrupted by climate change.
“We should expect much more political destabilisation of countries as it bites,” says Richard Choularton, a policy officer in the un’s World Food Programme climate change office. “What is different now from 20 years ago is that far more people are living in places with a higher cli- matic risk; 650 million people now live in arid or semi-arid areas where floods and droughts and price shocks are expected to have the most impact.
“the recent crises in the Horn of Africa and Sahel may be becoming the new normal. Droughts are expected to become more frequent. Studies suggest anything up to 200 million more food- insecure people by 2050 or an additional 24 million malnourished children. In parts of Africa we already have a protracted and growing humanitarian disaster. Climate change is a creep- ing disaster,” he said.
the Mary Robinson climate justice foundation is hosting a major conference in Dublin this week. Research to be presented there will say that rising incomes and growth in the global population, expected to create 2 billion more mouths to feed by 2050, will drive food prices higher by 40–50%. Climate change may add a further 50% to maize prices and slightly less to wheat, rice and oil seeds.
“We know population will grow and incomes increase, but also that temperatures will rise and rainfall patterns will change. We must prepare today for higher temperatures in all sec- tors,” said Gerald nelson, a senior economist with the International Food Policy Research Institute in Washington.
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All of the studies suggest the worst impacts will be felt by the poorest people. Robinson, the former Irish president, said: “Climate change is already having a domino effect on food and nutritional security for the world’s poorest and most vulnerable people. Child malnutrition is predicted to increase by 20% by 2050. Climate change impacts will disproportionately fall on people living in tropical regions, and particularly on the most vulnerable and marginalised population groups. this is the injustice of climate change—the worst of the impacts are felt by those who contributed least to causing the problem.”
Apply Your Knowledge the issue of global climate change raises a number of ethical issues. For example, greenhouse gas emissions by individuals in the present are causing climate change impacts that affect peo- ple in the future, people who have no say or input into the decisions we make and the actions we take today. Review this reading on Ethics and Global Climate Change (http://www.nature .com/scitable/knowledge/library/ethics-and-global-climate-change-84226631). What are the main points being made by the authors? Should ethical considerations play a role in deciding what, if anything, we should do to address climate change?
But from Europe to the uS to Asia, no population will remain insulated from the huge changes in food production that the rest of the century will bring.
Frank Rijsberman, head of the world’s leading Cgiar crop research stations, said: “there’s a lot of complacency in rich countries about climate change. We must understand that instabil- ity is inevitable. We already see a lot of refugees. Perhaps if a lot of people come over on boats to Europe or the uS that would wake them up.”
Impacts on Asia and Oceania China is relatively resilient to climate change. Its population is expected to decline by up [to] 400 million people this century, easing demand on resources, and it has the capacity to buy in vast quantities of food.
But because more and more Chinese are changing to a more meat-based diet, its challenges will be land and cattle feed. Climate change will affect regions in different ways, but many crops are expected to migrate northwards.
Crop losses are increasingly being caused by extreme weather events, insect attacks and dis- eases. the 2011 drought lifted food prices worldwide. Wheat is becoming harder to grow in some northern areas of China as the land gets drier and warmer.
In southern China, droughts in recent years have replaced rainy seasons. the national acad- emy of agricultural sciences expects basic food supplies to become insufficient around the year 2030.
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A new study for uS Aid expects most of Vietnam, Cambodia, Laos and thailand to see 4–6C temperature rises by 2050. the Lower Mekong region of 100 mil- lion people, which is prone to weather extremes, could also see rainfall increase 20% or more in some areas, reducing the growth of rice and other staple crops. Many provinces will see food production decline significantly. the number of malnourished chil- dren in the region may increase by 9 to 11 million by 2050.
Extreme events will increasingly affect agriculture in Australia. Key food-growing regions in the south are likely to experience more droughts in the future, with part of western Austra- lia having already experienced a 15% drop in rainfall since the mid-1970s.
the number of record-breaking hot days in Australia has doubled since the 1960s, also affect- ing food output.
Impacts on Europe Climate change affects agricultural production through its effects on the timing, intensity and variability of rainfall and shifts in temperatures and carbon dioxide concentrations.
Crops normally seen growing in the south of Europe will be able to be grown further north. this would allow more sweetcorn, grapes, sunflowers, soya and maize to be grown in Britain. In Scotland, livestock farming could become more suitable. At the higher latitudes warmer temperatures are predicted to lengthen and increase the intensity of the growing season. But more Co2 and a major temperature rise could cut yields by around 10% later in the century.
Latest Eu projections suggest the most severe consequences of climate change will not be felt until 2050. But significant adverse impacts are expected earlier from more frequent and prolonged heatwaves, droughts and floods. Many crops now grown in southern Europe, such as olives, may not survive high temperature increases. Southern Europe will have to change the way it irrigates crops.
In Europe’s high and middle latitudes, global warming is expected to greatly expand the grow- ing season. Crops in Russia may be able to expand northwards but yields will be much lower because the soils are less fertile. In the south, the climate is likely to become much drier which will reduce yields. In addition, climate change is expected to make water resources scarcer and encourage weeds and pests.
In 2011, Russia banned wheat and grain exports after a heatwave. Warming will increase for- est fires by 30-40%. this will affect soil erosion and increase the probability of floods.
© Bryan Denton/Corbis
Climate change is expected to increase extreme weather events in the Pacific islands. Here, aftermath of Super Typhoon Haiyan’s devastation in the Philippines. It was one of the most powerful typhoons ever recorded, with sustained winds of nearly 200 mph.
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In the Middle East and north Africa, declining yields of up to 30% are expected for rice, about 47% for maize and 20% for wheat.
Impacts on the Americas the uS is expected to grow by 120 million people by 2050. Government scientists expect more incidents of extreme heat, severe drought, and heavy rains to affect food production. the warming is expected to continue without undue problems for 30 years but beyond 2050 the effects could be dramatic with staple crops hit.
According to the latest government report: “the rising incidence of weather extremes will have increasingly negative impacts on crop and livestock productivity, because critical thresh- olds are already being exceeded.” Many agricultural regions of the uS will experience declines.
California’s central valley will be hard hit with sunflowers, wheat, tomato, rice, cotton and maize expected to lose 10–30% of their yields, especially beyond 2050. Fruit and nut crops which depend on “winter chilling” days may have to relocate. Animals exposed to many hot nights are increasingly stressed. Many vegetable crops will be hit when temperatures rise only a few degrees above normal.
nearly 20% of all uS food is imported, so climate extremes elsewhere will also have an effect. In 2011, 14.9% of uS households did not have secure food supplies and 5.7% had very low food security.
Because few crops can withstand average temperature rises of more than 2C, Latin America expects to be seriously affected by a warming climate and more extreme weather. Even mod- erate 1–2C rises would cause significant damage to Brazil, one of the world’s biggest suppli- ers of food crops. Brazilian production of rice, beans, manioc, maize and soya are all expected to decline, with coffee especially vulnerable.
other studies suggest Brazil’s massive soya crop, which provides animal feed for much of the world, could slump by more than 25% over the next 20 years.
two major crops should do well: quinoa and potatoes.
Impacts on Africa Many African countries are already experiencing longer and deeper droughts, floods and cyclones. the continent is expected to suffer disproportionately from food insecurity, due to fast-growing vulnerable populations.
Egypt expects to lose 15% of its wheat crops if temperatures rise 2C, and 36% if the increase is 4C. Morocco expects crops to remain stable up to about 2030, but then to drop quickly later. Most north African countries traditionally import wheat and are therefore highly vulnerable to price shocks and droughts elsewhere.
A new study of 11 west African countries expects most to be able to grow more food as tem- peratures rise and rainfall increases. But demand from growing populations may double food
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prices. Climate change may mean nigeria, Ghana and togo can grow and export more sor- ghum, raised for grain.
temperatures are expected to rise several degrees in regions close to the Sahel. In Burkina Faso, the sorghum crop is expected to decline by 25% or more, but maize yields may improve.
other studies by IFPRI suggest crop yields across sub-Saharan Africa may decline 5–22% by 2050, pushing large numbers of people deeper into destitution.
A new un study suggests climatic conditions in southern Africa will worsen. Climate models mostly predict an increase in annual maximum temperatures in the region of 1 to 2C by 2050. this will favour some crops but shift others to higher ground or further north.
Both of Africa’s staple crops, maize and sorghum, are expected to be badly hit by increasing severity of weather.
oxfam warns that small-scale farmers in the Horn of Africa will bear the brunt of the nega- tive impacts of climate change. unpredictable weather here has already left millions semi- destitute and dependent on food aid.
From Vidal, J. (2013, April 13). Climate change: How a warming world is a threat to our food supplies. the observer. Retrieved from http://www.theguardian.com/environment/2013/apr/13/climate-change-threat-food-supplies Copyright Guardian News & Media Ltd 2007. Used by permission.
7.4 Stratospheric Ozone Depletion The issues of global climate change and stratospheric ozone depletion are often confused and assumed to be the same problem. In fact, stratospheric ozone depletion is fundamentally a separate issue from climate change even though there are some areas of overlap. In this read- ing, staff writers with the U.S. Environmental Protection Agency (EPA) explain the importance of the Earth’s stratospheric ozone layer and review the major causes of ozone depletion in recent decades.
Ozone is a molecule made up of three oxygen atoms. In the troposphere, where we live and breathe, ozone is considered a dangerous pollutant (see section 9.1) that can aggravate respira- tory conditions and damage lung tissue. However, in the stratosphere, 15–30 kilometers above the Earth’s surface, an abundance of ozone known as the ozone layer serves a very useful pur- pose. The stratospheric ozone layer absorbs a significant percentage of UVB radiation coming from the sun. UVB radiation is known to cause skin cancer and cataracts and to harm plant and marine life. For this reason, it’s been said that ozone is “good up high, but bad nearby.”
Ozone in the stratosphere naturally undergoes a process of destruction and re-creation as it is bombarded by solar UVB radiation and is also broken down by naturally occurring chlorine that can occasionally reach the stratosphere. This process of creation and destruction can be likened to a bathtub half filled with water, with the faucet on but the drain also open. As long as water
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is flowing into the bathtub (ozone creation) at the same rate it is being drained out (ozone destruction), the level of water (ozone) in the bathtub will stay the same.
In the 1970s scientists began to speculate that a class of chemical compounds known as chloro- fluorocarbons (CFCs) could be affecting the ozone layer. They hypothesized that because CFCs (which contain chlorine) were so stable, they could be carried by winds and air updrafts to the stratosphere where powerful UVB radiation could break them apart, releasing chlorine. This extra chlorine could speed up ozone depletion and reduce the process of ozone creation— essentially opening the bathtub drain a little more and slowing the rate of water coming out of the faucet.
By the 1980s, scientists working in Antarctica measured large seasonal declines in stratospheric ozone over that continent, giving rise to the phrase “ozone hole.” Satellite-based instruments measuring ozone concentrations in terms of Dobson Units—a unit of measure developed spe- cifically to determine ozone density—confirmed this trend, and further sampling of chlorine in the stratosphere determined that CFC-based chlorine was responsible for most of the decline in ozone concentrations. In response to this scientific evidence, the nations of the world agreed to the Montreal Protocol in 1987, which eventually led to the phase out of most ozone-depleting substances (ODSs) worldwide. The case of ozone depletion is one of the rare instances where nations around the world responded cooperatively to a truly global environmental challenge. As a result, there is some indication that the ozone layer is recovering from recent low levels and that a major global environmental catastrophe may have been averted. The question that many environmental scientists and others ask themselves is why we were able to gain consensus and take action to address ozone depletion so quickly compared to our lack of action on climate change. You’ll have a chance to ask yourself this very question in the Critical thinking and Dis- cussion Questions section at the end of this chapter.
By Staff for the Environmental Protection Agency (EPA) the Earth’s ozone layer protects all life from the sun’s harmful radiation, but human activities have damaged this shield. Less protection from ultraviolet light will, over time, lead to higher skin cancer and cataract rates and crop damage. the u.S., in cooperation with 190 other coun- tries, is phasing out the production of ozone-depleting substances in an effort to safeguard the ozone layer.
The Ozone Layer the Earth’s atmosphere is divided into several layers. the lowest region, the troposphere, extends from the Earth’s surface up to about 10 kilometers (km) in altitude. Virtually all human activities occur in the troposphere. Mt. Everest, the tallest mountain on the planet, is only about 9 km high. the next layer, the stratosphere, continues from 10 km to about 50 km. Most commercial airline traffic occurs in the lower part of the stratosphere.
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[M]ost atmospheric ozone is concentrated in a layer in the stratosphere, about 15–30 kilo- meters above the Earth’s surface. ozone is a molecule containing three oxygen atoms. It is blue in color and has a strong odor. normal oxygen, which we breathe, has two oxygen atoms and is colorless and odorless. ozone is much less common than normal oxygen. out of each 10 million air molecules, about 2 million are normal oxygen, but only 3 are ozone.
Figure 7.4: The ozone layer
the ozone layer is found in the lower stratosphere about 15–30 km above the Earth’s surface. Its importance to humanity stems from stratospheric ozone’s ability to absorb a portion of the sun’s uVB radiation, which has been linked to various types of skin cancer and cataracts and can harm crops and some marine life.
However, even the small amount of ozone plays a key role in the atmosphere. the ozone layer absorbs a portion of the radiation from the sun, preventing it from reaching the planet’s surface. Most importantly, it absorbs the portion of ultraviolet light called uVB. uVB has been linked to many harmful effects, including various types of skin cancer, cataracts, and harm to some crops, certain materi- als, and some forms of marine life.
Consider This How do small numbers of ozone molecules in the stratosphere, more than 10 kilome- ters above the Earth’s surface, help protect life on Earth?
Troposphere
Stratosphere
Ozone layer
Earth
Mt. Everest
9 km
10 km
50 km Ozone layer
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At any given time, ozone molecules are constantly formed and destroyed in the stratosphere. the total amount, however, remains relatively stable. the concentration of the ozone layer can be thought of as a stream’s depth at a particular location. Although water is constantly flowing in and out, the depth remains constant.
While ozone concentrations vary naturally with sunspots, the seasons, and latitude, these processes are well understood and predictable. Scientists have established records span- ning several decades that detail normal ozone levels during these natural cycles. Each natural reduction in ozone levels has been followed by a recovery. Recently, however, convincing sci- entific evidence has shown that the ozone shield is being depleted well beyond changes due to natural processes.
Ozone Depletion For over 50 years, chlorofluorocarbons (CFCs) were thought of as miracle substances. they are stable, nonflammable, low in toxicity, and inexpensive to produce. over time, CFCs found uses as refrigerants, solvents, foam blowing agents, and in other smaller applications. other chlorine-containing compounds include methyl chloroform, a solvent, and carbon tetrachlo- ride, an industrial chemical. Halons, extremely effective fire extinguishing agents, and methyl bromide, an effective produce and soil fumigant, contain bromine. All of these compounds have atmospheric lifetimes long enough to allow them to be transported by winds into the stratosphere. Because they release chlorine or bromine when they break down, they damage the protective ozone layer. the discussion of the ozone depletion process below focuses on CFCs, but the basic concepts apply to all of the ozone-depleting substances (oDS).
In the early 1970s, researchers began to investigate the effects of various chemicals on the ozone layer, particularly CFCs, which contain chlorine. they also examined the potential impacts of other chlorine sources. Chlorine from swimming pools, industrial plants, sea salt, and volcanoes does not reach the stratosphere. Chlorine compounds from these sources readily combine with water and repeated measurements show that they rain out of the tropo- sphere very quickly. In contrast, CFCs are very stable and do not dissolve in rain. thus, there are no natural processes that remove the CFCs from the lower atmosphere. over time, winds drive the CFCs into the stratosphere.
the CFCs are so stable that only exposure to strong uV radiation breaks them down. When that happens, the CFC molecule releases atomic chlorine. one chlorine atom can destroy over 100,000 ozone molecules. the net effect is to destroy ozone faster than it is naturally created. to return to the analogy comparing ozone levels to a stream’s depth, CFCs act as a siphon, removing water faster than normal and reducing the depth of the stream.
Large fires and certain types of marine life produce one stable form of chlorine that does reach the stratosphere. However, numerous experiments have shown that CFCs and other widely-used chemicals produce roughly 84% of the chlorine in the stratosphere, while natu- ral sources contribute only 16%.
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Consider This What is the relative importance of natu- ral causes and human releases of CFCs in contributing to stratospheric ozone deple- tion? What is it about CFCs that help make them so effective at destroying ozone in the stratosphere?
Large volcanic eruptions can have an indirect effect on ozone levels. Although Mt. Pinatubo’s [in the Philippines] 1991 eruption did not increase stratospheric chlorine concentrations, it did produce large amounts of tiny particles called aerosols (different from consumer prod- ucts also known as aerosols). these aero- sols increase chlorine’s effectiveness at destroying ozone. the aerosols only increased depletion because of the pres- ence of CFC-based chlorine. In effect, the aerosols increased the efficiency of the CFC siphon, lowering ozone levels even more than would have otherwise occurred. unlike long-term ozone depletion, however, this effect is short-lived. the aerosols from Mt. Pinatubo have disappeared, but satellite, ground-based, and balloon data still show ozone depletion occurring closer to the historic trend.
The Ozone Hole one example of ozone depletion is the annual ozone “hole” over Antarctica that has occurred during the Antarctic Spring since the early 1980s. Rather than being a literal hole through the layer, the ozone hole is a large area of the stratosphere with extremely low amounts of ozone. ozone levels fall by over 60% during the worst years.
Apply Your Knowledge Given that the ozone layer is 15–30 kilometers (9–18 miles) above the Earth’s surface, how is it possible for scientists to know just how CFCs are impacting ozone concentrations? using your understanding of the scientific method, write out some possible approaches that sci- entists may have used to study this issue. It often takes a significant amount of time from when scientists first hypothesize a problem—such as the connection between CFCs and ozone depletion—and when they can actually collect enough evidence to support that hypothesis. Given that, should politicians always wait until a significant amount of research is completed or should they act in advance? What are the dangers of waiting until the science is close to completely settled? What are the dangers of acting too far in advance?
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In addition, research has shown that ozone depletion occurs over the latitudes that include north America, Europe, Asia, and much of Africa, Australia, and South America. over the u.S., ozone levels have fallen 5–10%, depending on the season. thus, ozone depletion is a global issue and not just a problem at the South Pole.
Reductions in ozone levels will lead to higher levels of uVB reaching the Earth’s surface. the sun’s output of uVB does not change; rather, less ozone means less protection, and hence more uVB reaches the Earth. Studies have shown that in the Antarctic, the amount of uVB measured at the surface can double during the annual ozone hole. Another study confirmed the relationship between reduced ozone and increased uVB levels in Canada during the past several years.
Laboratory and epidemiological studies demonstrate that uVB causes nonmelanoma skin cancer and plays a major role in malignant melanoma development. In addition, uVB has been linked to cataracts. All sunlight contains some uVB, even with normal ozone levels. It is always important to limit exposure to the sun. However, ozone depletion will increase the amount of uVB, which will then increase the risk of health effects. Furthermore, uVB harms some crops, plastics and other materials, and certain types of marine life.
September 17, 1979 October 7, 1989
October 9, 2006 October 1, 2010
NASA
The ozone layer protects Earth from the sun’s deadly radiation. Here, changes in the hole above Antarctica since 1979 are shown. The dark blue and purple colors are indicative of high levels of ozone loss. The use of chlorofluorocarbons was a key driver in creating the hole in the ozone layer.
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SECtIon 7.5Case history—Carbon dioxide and oCean aCidifiCation
The World’s Reaction the initial concern about the ozone layer in the 1970s led to a ban on the use of CFCs as aero- sol propellants in several countries, including the u.S. However, production of CFCs and other ozone-depleting substances grew rapidly afterward as new uses were discovered.
through the 1980s, other uses expanded and the world’s nations became increasingly con- cerned that these chemicals would further harm the ozone layer. In 1985, the Vienna Con- vention was adopted to formalize international cooperation on this issue. Additional efforts resulted in the signing of the Montreal Protocol in 1987. the original protocol would have reduced the production of CFCs by half by 1998.
After the original Protocol was signed, new measurements showed worse damage to the ozone layer than was originally expected. In 1992, reacting to the latest scientific assessment of the ozone layer, the Parties to the Protocol decided to completely end production of halons by the beginning of 1994 and of CFCs by the beginning of 1996 in developed countries.
Because of measures taken under the Montreal Protocol, emissions of ozone-depleting sub- stances are already falling. Levels of total inorganic chlorine in the stratosphere peaked in 1997 and 1998. the good news is that the natural ozone production process will heal the ozone layer in about 50 years.
Adapted from ozone Science: the Facts Behind the Phaseout. United States Environmental Protection Agency. Retrieved from http://www.epa.gov/ozone/science/sc_fact.html
7.5 Case History—Carbon Dioxide and Ocean Acidification For the past few decades climate scientists have been puzzled by an inconsistency between the rate of human emissions of carbon dioxide (CO2) to the atmosphere and the rate of increase in atmospheric concentrations of this gas. Based on the amount of fossil fuel we knew we were burning, scientists expected atmospheric CO2 levels to be increasing faster than they actually were. Some scientists dubbed this the “missing carbon” problem. It turns out that a significant portion of the excess CO2 that we were emitting into the air was being absorbed by the world’s oceans, an apparently fortunate fact that has helped to moderate increases in global tempera- ture. However, it also turns out that the uptake of CO2 by the seas is changing the very chemistry of the oceans, perhaps in highly destructive ways.
In this article, science reporter Carl Zimmer summarizes the results of recent research on how changes in acidity can play a huge role in the health and productivity of the seas. This research relied heavily on the analysis of ancient sediment taken from the sea floor. This sediment pro- vides a snapshot of what the oceans were like over millions of years. What scientists have found is that when the oceans are relatively non-acidic, there is an abundance of marine life supported by single-celled organisms with shells of calcium carbonate (what chalk is made from). Over millions of years these organisms lived, died, and sank to the bottom of the ocean leaving lay- ers of white sediment that today can be seen as white cliffs in some locations. However, this same research shows that when oceans turn even moderately more acidic, the white sediment
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is replaced with red clay, suggesting a massive change in the chemistry, productivity, and biodi- versity of the world’s oceans.
Much of the excess CO2 that we are currently emitting to the atmosphere is being absorbed by the oceans where it is changing ocean chemistry and making these bodies of water more acidic. In this way CO2 is not only changing the climate but also changing the oceans. The consequences of such a change could be dramatic and devastating, adding even more urgency to the need to address greenhouse gas emissions. The next chapter will review a variety of approaches to using energy more efficiently and meeting our energy needs in new ways that offers some hope for reducing CO2 emissions.
By Carl Zimmer the JOIDES Resolution looks like a bizarre hybrid of an oil rig and a cargo ship. It is, in fact, a research vessel that ocean scientists use to dig up sediment from the sea floor. In 2003, on a voyage to the southeastern Atlantic, scientists aboard the JOIDES Resolution brought up a particularly striking haul.
they had drilled down into sediment that had formed on the sea floor over the course of mil- lions of years. the oldest sediment in the drill was white. It had been formed by the calcium carbonate shells of single-celled organisms—the same kind of material that makes up the White Cliffs of Dover. But when the scientists examined the sediment that had formed 55 mil- lion years ago, the color changed in a geological blink of an eye.
“In the middle of this white sediment, there’s this big plug of red clay,” says Andy Ridgwell, an earth scientist at the university of Bristol.
In other words, the vast clouds of shelled creatures in the deep oceans had virtually disappeared. Many sci- entists now agree that this change was caused by a drastic drop of the ocean’s pH level. the seawater became so cor- rosive that it ate away at the shells, along with other species with calcium carbonate in their bodies. It took hun- dreds of thousands of years for the oceans to recover from this crisis, and for the sea floor to turn from red back to white.
A Warning for the Future the clay that the crew of the JOIDES Resolution dredged up may be an omi- nous warning of what the future has in store. By spewing carbon dioxide into the air, we are now once again making the oceans more acidic.
Ira Block/National Geographic Creative
A researcher holds a replica of the core sample showing an abrupt change in sea floor sediment approximately 55 million years ago. Scientists believe a catastrophic drop in oceanic pH levels, known as the Paleocene-Eocene thermal maximum, was responsible for the widespread death of calcium carbonate bodied sea creatures.
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SECtIon 7.5Case history—Carbon dioxide and oCean aCidifiCation
today, Ridgwell and Daniela Schmidt, also of the university of Bristol, are publishing a study in the journal Natural Geoscience, comparing what happened in the oceans 55 million years ago to what the oceans are experiencing today. their research supports what other researchers have long suspected: the acidification of the ocean today is bigger and faster than anything geologists can find in the fossil record over the past 65 million years. Indeed, its speed and strength—Ridgwell estimate[s] that current ocean acidification is taking place at ten times the rate that preceded the mass extinction 55 million years ago—may spell doom for many marine species, particularly ones that live in the deep ocean.
“this is an almost unprecedented geological event,” says Ridgwell.
When we humans burn fossil fuels, we pump carbon dioxide into the atmosphere, where the gas traps heat. But much of that carbon dioxide does not stay in the air. Instead, it gets sucked into the oceans. If not for the oceans, climate scientists believe that the planet would be much warmer than it is today. Even with the oceans’ massive uptake of Co2, the past decade was still the warmest since modern record-keeping began. But storing carbon dioxide in the oceans may come at a steep cost: It changes the chemistry of seawater.
At the ocean’s surface, seawater typically has a pH of about 8 to 8.3 pH units. For comparison, the pH of pure water is 7, and stomach acid is around 2. the pH level of a liquid is determined by how many positively charged hydrogen atoms are floating around in it. the more hydrogen ions, the lower the pH. When carbon dioxide enters the ocean, it lowers the pH by reacting with water.
the carbon dioxide we have put into the atmosphere since the Industrial Revolution has low- ered the ocean pH level by .1. that may seem tiny, but it’s not. the pH scale is logarithmic, meaning that there are 10 times more hydrogen ions in a pH 5 liquid than one at pH 6, and 100 times more than pH 7. As a result, a drop of just .1 pH units means that the concentration of hydrogen ions in the ocean has gone up by about 30 percent in the past two centuries.
The Impacts of Ocean Acidification to see how ocean acidification is going to affect life in the ocean, scientists have run labora- tory experiments in which they rear organisms at different pH levels. the results have been worrying—particularly for species that build skeletons out of calcium carbonate, such as cor- als and amoeba-like organisms called foraminifera. the extra hydrogen in low-pH seawater reacts with calcium carbonate, turning it into other compounds that animals can’t use to build their shells.
these results are worrisome, not just for the particular species the scientists study, but for the ecosystems in which they live. Some of these vulnerable species are crucial for entire ecosys- tems in the ocean. Small shell-building organisms are food for invertebrates, such as mollusks and small fish, which in turn are food for larger predators. Coral reefs create an underwater rain forest, cradling a quarter of the ocean’s biodiversity.
But on their own, lab experiments lasting for a few days or weeks may not tell scientists how ocean acidification will affect the entire planet. “It’s not obvious what these mean in the real world,” says Ridgwell.
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SECtIon 7.5Case history—Carbon dioxide and oCean aCidifiCation
one way to get more information is to look at the history of the oceans themselves, which is what Ridgwell and Schmidt have done in their new study. At first glance, that history might suggest we have nothing to worry about. A hundred million years ago, there was over five times more carbon dioxide in the atmosphere and the ocean was .8 pH units lower. Yet there was plenty of calcium carbonate for foraminifera and other species. It was during this period, in fact, that shell-building marine organisms produced the limestone formations that would eventually become the White Cliffs of Dover.
But there’s a crucial difference between the Earth 100 million years ago and today. Back then, carbon dioxide concentrations changed very slowly over millions of years. those slow changes triggered other slow changes in the Earth’s chemistry. For example, as the planet warmed from more carbon dioxide, the increased rainfall carried more minerals from the mountains into the ocean, where they could alter the chemistry of the sea water. Even at low pH, the ocean contains enough dissolved calcium carbonate for corals and other species to survive.
today, however, we are flooding the atmosphere with carbon dioxide at a rate rarely seen in the history of our planet. the planet’s weathering feedbacks won’t be able to compensate for the sudden drop in pH for hundreds of thousands of years.
Scientists have been scouring the fossil record for periods of history that might offer clues to how the planet will respond to the current carbon jolt. they’ve found that 55 million years ago, the Earth went through a similar change. Lee Kump of Penn State and his colleagues have estimated that roughly 6.8 trillion tons of carbon entered the Earth’s atmosphere over about 10,000 years.
nobody can say for sure what unleashed all that carbon, but it appeared to have had a drastic effect on the climate. temperatures rose between 5 and 9 degrees Celsius (9 to 16 Fahren- heit). Many deep-water species became extinct, possibly as the pH of the deep ocean became too low for them to survive.
But this ancient catastrophe (known as the Paleocene-Eocene thermal maximum, or PEtM) was not a perfect prequel to what’s happening on Earth today. the temperature was warmer before the carbon bomb went off, and the pH of the oceans was lower. the arrangement of the continents was also different. the winds blew in different patterns as a result, driving the oceans in different directions. All these factors make a big difference on the effect of ocean acidification. For example, the effect that low pH has on skeleton-building organisms depends on the pressure and temperature of the ocean. Below a certain depth in the ocean, the water becomes so cold and the pressure so high that there’s no calcium carbonate left for shell- building organisms. that threshold is known as the saturation horizon.
to make a meaningful comparison between the PEtM and today, Ridgwell and Schmidt built large-scale simulations of the ocean at both points of time. they created a virtual version of the Earth 55 million years ago and let the simulation run until it reached a stable state. the pH level of their simulated ocean fell within the range of estimates of the pH of the actual ocean 55 millions years ago. they then built a version of the modern Earth, with today’s arrange- ments of continents, average temperature, and other variables. they let the modern world reach a stable state and then checked the pH of the ocean. once again, it matched the real pH found in the oceans today.
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Ridgwell and Schmidt then jolted both of these simulated oceans with massive injections of carbon dioxide. they added 6.8 trillion tons of carbon over 10,000 years to their PEtM world. using conservative projections of future carbon emissions, they added 2.1 trillion tons of car- bon over just a few centuries to their modern world. Ridgwell and Schmidt then used the model to estimate how easily carbonate would dissolve at different depths of the ocean.
the results were strikingly different. Ridgwell and Schmidt found that ocean acidification is happening about ten times faster today than it did 55 million years ago. And while the satura- tion horizon rose to 1,500 meters 55 million years ago, it will lurch up to 550 meters on aver- age by 2150, according to the model.
A New Wave of Extinctions? the PEtM was powerful enough to trigger widespread extinctions in the deep oceans. today’s faster, bigger changes to the ocean may well bring a new wave of extinctions. Paleontologists haven’t found signs of major extinctions of corals or other carbonate-based species in surface waters around PEtM. But since today’s ocean acidification is so much stronger, it may affect life in shallow water as well. “We can’t say things for sure about impacts on ecosystems, but there is a lot of cause for concern,” says Ridgwell.
Ellen thomas, a paleoceanographer at Yale university, says that the new paper “is highly sig- nificant to our ideas on ocean acidification.” But she points out that life in the ocean was buf- feted by more than just a falling pH. “I’m not convinced it’s the whole answer,” she says. the ocean’s temperature rose and oxygen levels dropped. together, all these changes had complex effects on the ocean’s biology 55 million years ago. Scientists now have to determine what sort of combined effect they will have on the ocean in the future.
our carbon-fueled civilization is affecting life everywhere on Earth, according to the work of scientists like Ridgwell—even life that dwells thousands of feet underwater. “the reach of our actions can really be quite global,” says Ridgwell. It’s entirely possible that the ocean sedi- ments that form in the next few centuries will change from the white of calcium carbonate back to red clay, as ocean acidification wipes out deep-sea ecosystems.
“It will give people hundreds of millions of years from now something to identify our civiliza- tion by,” says Ridgwell.
Adapted from Zimmer, C. (2010). An Ominous Warning on the Effects of Ocean Acidification. Yale Environment 360. Retrieved from http://e360.yale.edu/feature/an_ominous_warning_on_the__effects_of_ocean_acidification /2241/ Copyright Carl Zimmer. Reprinted by permission of the author.
Summary & Resources
Chapter Summary It’s been said that Earth has a “Goldilocks” or “just right” atmosphere, due to mild and habit- able temperatures. nearby planets of Venus and Mars are incredibly hotter or colder than our planet. this difference cannot be explained by distance from the sun, but instead it is due mostly to the atmospheric composition of each planet. For example, greenhouse gases in a planet’s atmosphere, such as carbon dioxide, act as an insulating blanket and help trap
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infrared or heat energy as it leaves a planet’s surface. the atmosphere of Venus is made up mainly of carbon dioxide, so its surface temperature is nearly 1,000 °F. Mars has almost no greenhouse gases, so its surface temperature is a frigid –120 °F. In contrast, water vapor and small quantities of carbon dioxide and other greenhouse gases help keep the Earth’s average surface temperature at a comfortable 59 °F.
What concerns scientists is the degree to which human activities, such as the burning of fossil fuels, enhance this natural greenhouse effect and causes global warming and global climate change. Because the global climate system is so vast and complex, there are areas of uncer- tainty over the causes and consequences of climate change. Scientists have had to grapple with whether the observed warming of Earth’s atmosphere in recent decades is a result of human factors or due to natural causes. Additionally, researchers are investigating whether recent changes in weather patterns in different parts of the world can be linked to climate change.
Given that the possible consequences of climate change have the potential to impact so many people, the politics of the issue are complicated. Because climate change is a global envi- ronmental problem, it will require global cooperation to address it. However, nations of the world have (to date) made very limited progress as they try to agree on how to tackle climate change. this is due to sharp differences in beliefs over what should be done and who should pay for it.
In contrast, the global community was able to agree on how to address a different global envi- ronmental challenge, that of stratospheric ozone depletion. While the ozone depletion issue was also complex in its own way, the causes were more easily understood, the consequences more imminent, and the solutions more straightforward than those for climate change. As a result, action was swifter and more effective on this issue than it has been for climate change.
there are a number of key lessons that we can take away from the study of climate change and stratospheric ozone depletion. Global environmental challenges are highly complex, and scientific understanding of causes and effects often takes years to research. In the meantime, while waiting for more definitive scientific proof, the problem can worsen and perhaps even become irreversible. Policymakers must therefore decide whether to take action in the face of such uncertainty. Efforts to address ozone depletion through the Montreal Protocol highlight such action, as they began long before there was solid evidence linking the problem to CFCs. Action on climate change has been slower, in part, because the science is even more compli- cated and the political and economic stakes are much higher than for ozone depletion. Since one of the major contributors to climate change is the combustion of fossil fuels, proposals to deal with this problem have focused largely on the development of energy sources that do not emit greenhouse gases. the next chapter will review these energy sources, the challenges facing them, and their potential to help address the climate change issue.
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Working Toward Solutions At an international level the Kyoto Protocol (http://unfccc.int/kyoto_protocol/items/2830 .php) is the primary governmental effort to address the issue of climate change. First adopted in 1997, the Kyoto Protocol entered into force as a global treaty in 2005 and, as of Decem- ber 2012, 190 countries had ratified the treaty. the united States is the only country to sign the protocol but not ratify it, whereas Canada ratified the treaty but then withdrew from it. the Kyoto Protocol sets internationally binding greenhouse gas emission reduction targets on signatory countries, with more ambitious reduction targets for developed nations. Although India and China have both ratified the Kyoto Protocol, they are currently not obligated to reduce their greenhouse gas emissions. this is because they are both considered developing countries and their historical contributions to increased greenhouse gas concentrations have been minimal. overall, the Kyoto Protocol appears to have had very little impact on reducing greenhouse gas emissions. International climate change negotiations continue to be charac- terized by disputes over financial responsibility, the scale and timing of meeting reduction targets, and other procedural issues regarding the future of negotiations.
Political efforts to address and respond to climate change at the national level in the united States have arguably gone even worse than at the international level. Even though the united States was a signatory to the Kyoto Protocol in 1997, neither President Clinton, President Bush, nor President obama have made an effort to have it ratified by the u.S. Senate. other legislative efforts to address greenhouse gas emissions and climate change at the federal level have also gone nowhere. nevertheless, the u.S. Environmental Protection Agency and other federal agencies such as the Department of Defense are taking what they call “com- mon-sense steps” to reduce greenhouse gas emissions (http://www.epa .gov/climatechange /EPAactivities.html). these include efforts to improve energy efficiency, expand the use of renewable energy, and advance climate change science.
While the u.S. federal government has been slow to act on the issue of climate change, the same cannot be said for many state and local governments. For example, nine states in the northeast have formed a Regional Greenhouse Gas Initiative (http://www.rggi.org/), the first “market-based regulatory program in the united States to reduce greenhouse gas emissions.” California adopted a cap-and-trade program in 2013 (http://www.arb.ca.gov/cc/capandtrade /capandtrade.htm) that allows polluting industries to buy and sell greenhouse gas emission permits from each other, while gradually reducing overall emission levels over time. other states are developing climate action plans, setting renewable energy targets, and promoting energy efficiency in homes and businesses to help reduce greenhouse gas emissions.
Private companies and institutions such as colleges and universities are also increasingly taking steps to lower their greenhouse gas emissions. these companies and institutions are motivated both by a desire to do what they can to avoid climate change as well as by the financial savings that usually come from reducing energy use. For example, in 2009 the Busi- ness Roundtable released a report (http://businessroundtable.org/studies-and-reports/the -balancing-act-climate-change-energy-security-and -the-u.s.-economy/) outlining how mem- ber companies could both reduce greenhouse gas emissions and increase profitability. Like- wise, the American College and university Presidents’ Climate Commitment (http://www .presidentsclimatecommitment.org/) now has over 600 schools that have signed on to inventory their greenhouse gas emissions and develop climate action plans to significantly reduce their
(continued)
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Post-test
1. the greenhouse effect is a natural phenomenon. a. true b. False
2. Major scientific assessments have determined that natural causes could be respon- sible for much of the observed changes to climate in recent decades.
a. true b. False
3. Food insecurity and rising food prices were a major factor in the unrest and upris- ings known as the Arab Spring
a. true b. False
4. the ozone layer that protects life on Earth is located primarily in what region of the atmosphere?
a. troposphere b. Mesosphere c. Stratosphere d. Ionosphere
5. Scientific research has revealed that excess carbon dioxide emissions are making the oceans less acidic.
a. true b. False
6. the most common greenhouse gas after water vapor is a. methane. b. nitrogen. c. carbon dioxide. d. chlorofluorocarbons.
7. Climate change can be expected to result in stronger hurricanes and more extreme weather events.
a. true b. False
Working Toward Solutions (continued) emissions. Lastly, individuals can take many small, but potentially cumulative, actions to reduce their own greenhouse gas emissions. the u.S. EPA provides a comprehensive guide (http://www.epa .gov/climatechange/wycd/) for what individuals can do at home, at work, at school, and on the road.
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8. Climate change will allow farmers in southern Europe to grow many crops now only grown in northern Europe.
a. true b. False
9. Which of the following is the best explanation of how the ozone layer protects life on Earth?
a. the ozone layer blocks incoming sunlight and prevents global warming. b. the ozone layer absorbs outgoing infrared energy and increases surface temperatures. c. the ozone layer absorbs uVB radiation from the sun that can cause skin cancer. d. the ozone layer shields sea ice from the sun and protects it from melting.
10. the primary concern among scientists over ocean acidification is that a. acidic sea water will cause sea level rise. b. acidic sea water will corrode the hulls of ships. c. acidic sea water prevents aquatic organisms from building calcium carbonate shells. d. acidic sea water changes the texture and flavor of ocean caught fish.
Answers 1. a. true. the answer can be found in section 7.1. 2. b. False. the answer can be found in section 7.2. 3. a. true. the answer can be found in section 7.3. 4. c. Stratosphere. the answer can be found in section 7.4. 5. b. False. the answer can be found in section 7.5. 6. c. carbon dioxide. the answer can be found in section 7.1. 7. a. true. the answer can be found in section 7.2. 8. b. False. the answer can be found in section 7.3. 9. c. the ozone layer absorbs uVB radiation from the sun that can cause skin cancer. the answer can be found in section 7.4. 10. c. acidic sea water prevents aquatic organisms from building calcium carbonate shells. the answer can be found in section 7.5.
Key Ideas • Scientific understanding of the connection between greenhouse gases and the
Earth’s climate dates back to the 19th century. However, it’s only been in the past few decades that concern has grown over the possibility that higher atmospheric concentrations of carbon dioxide and other greenhouse gases could lead to abrupt and catastrophic climate change.
• there is consistent and accumulating scientific evidence that global average tem- peratures are increasing and that this increase is due in large part to higher concen- trations of greenhouse gases—carbon dioxide (Co2), methane (CH4), and nitrous oxide (n2o)—from human activities. Continued emissions of these gases into the atmosphere could result in additional increases in global average temperatures of between 2 and 11.5 degrees Fahrenheit over the next century.
• Scientists refer to the addition of greenhouse gases to the atmosphere as the “enhanced greenhouse effect,” since it adds to the planet’s natural greenhouse effect. While this enhanced greenhouse effect does raise global average temperatures, sci- entists prefer the term “global climate change” over “global warming” because it also contributes to changes in wind patterns, precipitation, and other climate factors.
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• Some of the major impacts of global climate change that are projected occur—or that are already being observed—include more extreme weather, disruptions to water supply and water quality, negative impacts to human health, increased rates of extinction and biodiversity loss, and sea level rise.
• Climate change is already impacting precipitation, water supply, and food produc- tion in many regions of the world. Some of the regions where climate change will have the biggest negative impacts on food production are already among the poorest in the world.
• Climate change mitigation involves taking steps to reduce and eventually halt emis- sions of heat-trapping greenhouse gases into the atmosphere. In contrast, climate change adaptation accepts that some climate change has already occurred and that more is almost certain to occur in the decades ahead. therefore, adaptation involves making changes to how and where we live, where we grow food and secure our water, and other aspects of life in response to a changing climate.
• the ozone layer is located in the lower stratosphere roughly 15–30 kilometers above the Earth’s surface. the ozone layer helps to absorb a significant amount of the sun’s uVB radiation, protecting life on Earth from the harm that this radiation can cause.
• Chlorine from a class of chemicals known as chlorofluorocarbons (CFCs) has been found to deplete concentrations of ozone in the stratosphere, resulting in increased levels of uVB radiation reaching the Earth’s surface. Faced with strong scientific evidence for ozone depletion caused by CFCs, nations of the world took action to eliminate CFC use.
• Increased levels of carbon dioxide emissions from fossil fuel burning and other human activities is leading to changes in ocean acidity, making our seas more acidic. these changes could be catastrophic and lead to sharp declines in the productivity and biodiversity of the world’s oceans.
Critical thinking and Discussion Questions
1. think back to the discussion in the Introduction to this book of how the scientific method might be used to answer questions about the connection between road salt application and the death of trees. Scientists studying an issue like that face a fair amount of complexity in understanding the connections between salt application and tree mortality. Consider how much more complex the study of global climate must be. Scientists have observed that global average temperatures have increased at the same time that atmospheric levels of carbon dioxide have increased. What must these scientists do to try to discern whether one is caused by the other? What other factors might complicate their research?
2. the “debate” over global climate change is really based on a series of debates or questions about what is happening, what’s causing it, and what we should do about it. Specifically, there are three separate questions that scientists, politicians, and oth- ers find themselves grappling with: • Is the Earth getting warmer? Is the climate changing? • If the climate is changing, are human actions the primary cause of that change,
or can this be explained by natural causes? • If the climate is changing and human actions are the primary cause of that
change, what can or should be done about it?
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As suggested in the Introduction to this chapter, the first two questions are largely positive in nature; that is, they are questions about the way the world is. When scien- tists state that global average temperatures have increased by 1.5 degrees in the last century, and that this increase “is due primarily to human-induced increases in heat- trapping gases,” they are simply stating the results of their scientific research. When politicians use that information to argue for a change in policy to reduce greenhouse gas emissions, they move from the positive to the normative, making statements about the way the world should be. unfortunately, many climate change scientists have found themselves attacked personally and professionally for their research, and some major politicians in the united States have gone so far as to accuse the scien- tific community of engaging in a vast conspiracy to fool the American public about climate change. Given what you know about the scientific method and how it gov- erns the work of scientists, how do you feel about these political attacks on scien- tists? Should the checks and balances of the scientific method—hypothesis testing, peer review of research results—shield scientists from these sorts of accusations? Would an acceptance of a “yes” answer to the first two questions above—the world is warming and it’s due primarily to human activities—still leave room for a wide range of opinion and debate over question 3—what to do about it?
3. Given the changes that have already occurred to climate and the likelihood that no matter what we do additional climate change will occur in the decades ahead, the idea of adaptation to climate change takes on a new significance. What are some major ways that human society might have to adapt to a world with more extreme weather, sea level rise, water shortages, and changing disease patterns? Many experts point to the recent example of Hurricane Sandy as an indicator of what we could expect more of in the future. How could coastal areas like new York and new Jersey better prepare and adapt to increased frequency of storms like Sandy? Do wealthier countries—who are most responsible for increased greenhouse gas concentrations—have a moral obligation to help poorer countries adapt to climate change impacts?
4. Faced with growing scientific evidence of the link between CFC use and stratospheric ozone depletion, governments of the world took swift and dramatic action to begin the phaseout of CFCs and other ozone-depleting substances. As a result of this action there is some evidence that the ozone layer is beginning to recover. In contrast, and despite growing scientific evidence, nations of the world have made very little prog- ress in addressing or resolving the issue of global climate change. What might be some of the explanations for this difference in response? What is it about the causes, consequences, and solutions to each of these problems that could explain such dra- matically different responses?
5. the reading on ocean acidification raised the possibility that much of the marine life we know could be wiped out in a few centuries if current trends continue. What would be some of the most significant impacts of such a change? What groups might be most affected if this were to occur? Does the danger of ocean acidification add even more urgency to the need to move away from fossil fuels?
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Key terms
adaptation Making changes so as to become suitable to a new or special applica- tion or situation.
attribution Assigning some quality or char- acter to a person or thing.
Dobson Units A unit of measure developed specifically to determine ozone density.
geoengineering the deliberate interven- tion and modification of earth systems to prevent or reduce climate change.
greenhouse effect the global warming of our atmosphere caused by the presence of carbon dioxide and other greenhouse gases, which trap the sun’s radiation.
Kyoto Protocol An international treaty that stipulates highly developed countries must cut their emissions of carbon dioxide and other gases that cause climate warming by an average of 5.2 percent by 2012.
Montreal Protocol An international treaty designed to protect the ozone layer by phas- ing out the production of numerous sub- stances believed to be responsible for ozone depletion.
normative claim A claim about what some- one values; a statement of the way things should be.
ozone layer A layer in the Earth’s strato- sphere containing a high concentration of ozone, which absorbs most of the ultraviolet radiation from the sun.
positive claim A claim based on actual evi- dence; a statement of what we know.
stratosphere the layer of the atmosphere between the troposphere and the meso- sphere that contains a layer of ozone that protects life on earth by filtering out much of the sun’s ultraviolet radiation.
stratospheric ozone depletion the reduc- tion of the protective layer of ozone in the upper atmosphere by chemical pollution.
troposphere the lowest region of the atmosphere, extending from the Earth’s sur- face to a height of about 33,000 ft (10 km).
UVB radiation the part of the electro- magnetic spectrum with wavelengths just shorter than visible light; a high-energy form of radiation that can have damaging or lethal effects on organisms with higher levels of exposure.
Additional Resources there are a number of good resources available on the basic science behind the greenhouse effect and global climate change. Perhaps the most authoritative voice on this subject is the Intergovernmental Panel on Climate Change (IPCC). the IPCC (http://www.ipcc.ch/) is the leading international body for the assessment of climate change issues. note that the IPCC is charged with assessment of climate change science; they do not conduct their own research. Rather, they compile and attempt to make sense of the thousands of individual stud- ies conducted by scientists globally on this subject. the IPCC publishes highly detailed and comprehensive assessment reports on the science behind climate change, its impacts, and possible solutions (http://www.ipcc.ch/publications_and_data/publications_and_data_reports .shtml#.us9Y5fRDsy4). Particularly useful is a list of Frequently Asked Questions to which the IPCC provides answers (http://www.ipcc.ch/publications_and_data/ar4/wg1/en/faqs .html). At the national level, the united States Global Change Research Program (uSGCRP)
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coordinates federal research into climate change issues (http://www.globalchange.gov/). Like the IPCC, the uSGCRP has a number of publications available that provide detailed infor- mation on climate change issues as they relate specifically to the united States (http://www .globalchange.gov/resources/reports). the Center for Climate and Energy Solutions (C2ES) is an excellent source of information on basic climate change science and some of the pos- sible solutions to this challenge (http://www.c2es.org/). In particular, their Climate Change 101 Series does a great job of distilling the complex science behind climate change down to a level that’s accessible and understandable for most readers (http://www.c2es.org/science -impacts/climate-change-101). the national Aeronautics and Space Administration (nASA) has a site that shows recent and archived images of the ozone hole (http://ozonewatch.gsfc .nasa.gov/). national Geographic maintains a Global Warming page with a lot of good informa- tion (http://environment.nationalgeographic.com/environment/global-warming/), and the Annenberg Learner Project’s Habitable Planet series has a whole unit on this subject (http:// www.learner.org/courses/envsci/unit/text.php?unit=12&secnum=0). the journal Nature provides a fairly scientific and technical piece on the global climate system for readers who want more detail (http://www.nature.com/scitable/knowledge/library/the-global-climate -system-74649049). Lastly, Colorado State university sponsors a site called “100 Views of Cli- mate Change” that includes a wealth of resources on basic climate science, impacts of climate change, and ways to take action (http://changingclimates.colostate.edu/index.html).
In terms of climate change impacts, the online reporting of Yale Environment 360 (http:// e360.yale.edu/topic/climate/005/) presents easily accessible summaries of some of the ways in which climate change is expected to impact, or is already impacting, ecosystems and people. Particularly interesting are reports on a north Pole without ice (http://e360.yale .edu/feature/tipping_point_arctic_heads_to_ice_free_summers/2567/ and http://e360.yale .edu/slideshow/arctic_tipping_point_heading_to_an_ice-free_north_pole/120/1/), the link between climate change and extreme weather (http://e360.yale.edu/feature/whats_with _the_weather_is_climate_change_to_blame/2388/), how climate change is affecting animal behavior (http://e360.yale.edu/feature/with_temperatures_rising_here_comes_global _weirding/2132/), and the impact of climate change on sea level rise (http://e360.yale.edu /feature/battered_new_york_city_looks_for_ways_to_hold_back_the_sea/2589/). nASA pro- vides some very interesting animations and other information on climate change and strato- spheric ozone depletion (http://www.nasa.gov/topics/earth/index.html). one particularly interesting animation shows how much the northern hemisphere has warmed in the past 50 years (http://www.nasa.gov/topics/earth/features/warming-links.html). the New York Times had a series of articles in early 2013 that reported on how 2012 was officially the hottest year on record in the united States, and how climate change was being linked to extreme weather worldwide (http://www.nytimes.com/2013/01/09/science/earth/2012 -was-hottest-year-ever-in-us.html, http://www.nytimes.com/interactive/2013/01/08/science /earth/record-setting-heat-across-the-us-in-2012.html, http://www.nytimes.com/2013/01 /11/science/earth/extreme-weather-grows-in-frequency-and-intensity-around-world .html, and http://www.nytimes.com/slideshow/2013/01/11/science/earth/11extreme -slideshow.html). Lastly, the work of filmmaker Jason Balog illustrates just how rapidly climate change is occurring by documenting the loss of ice from glaciers and the polar regions in his film Chasing Ice (http://vimeo.com/48966552). this short clip shows what is con- sidered the largest glacier break up ever filmed (http://www.guardian.co.uk/environment /video/2012/dec/12/chasing-ice-iceberg-greenland-video).
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SuMMARY & RESouRCES
there are also many good resources on the politics and economics of climate change, including this report on how many businesses are doing their part to address the climate change issue while increasing profitability at the same time (http://www.c2es.org/publications/business -case-for-climate-legislation). this Yale Environment 360 report also argues that a strong eco- nomic case can be made for reducing carbon emissions (http://e360.yale.edu/feature/the _economic_case_for_slashing_carbon_emissions/2200/). this New York Times op-ed piece by university of California physicist Richard A. Muller describes how he gradually overcame his skepticism about climate change science and came to accept the growing scientific consen- sus around this issue (http://www.nytimes.com/2012/07/30/opinion/the-conversion-of-a -climate-change-skeptic.html). the piece by Muller is especially powerful because it describes how he approached the issue of climate change through the lens of the scientific method and how that helped him accept the importance of this issue. He rightly concludes the article by reminding us that even if we accept the science behind climate change, the real challenge will lie in deciding what we will do about the problem. this interview with South Carolina Repub- lican Bob Inglis reveals just how difficult the politics of this issue can be (http://e360.yale.edu /feature/interview_bob_inglis_conservative_who_believes_climate_change_is_real/2615/). Inglis lost his seat in Congress because of his willingness to state that he believed in human- caused climate change. the World Resources Institute (WRI) provides highly detailed and up- to-date information on the regulatory and political developments related to climate change (http://www.wri.org/our-work/project/us-climate-action). Finally, here are a few other resources that are very useful to the student wishing to learn more about global climate change. this national Science Foundation site has video interviews with over 50 leading cli- mate scientists on a variety of issues (http://www.nsf.gov/news/special_reports/degree/). Climate Central is an independent organization of leading climate scientists whose web page contains a range of resources on this subject (http://www.climatecentral.org). the Climate Literacy and Energy Awareness network (CLEAn) provides a wealth of resources to teachers and other educators on climate change issues (http://cleanet.org/index.html). Climate Con- nections archives stories heard on national Public Radio (nPR) on this subject (http://www .npr.org/series/9657621/climate-connections). this article analyzes the consensus that’s formed around climate change in the scientific literature, demonstrating that over 97 percent of scientific papers published on the subject endorse the consensus view (http://iopscience .iop.org/1748-9326/8/2/024024/article). this article reviews how climate change is causing entire ecosystems to have to shift or experience biodiversity loss and decline (http://www .sciencemag.org/content/341/6145/486.full). Lastly, these three articles cover the basics of “carbon budgeting” and illustrate just how little room is left for a continued reliance on fossil fuels if we are to avoid catastrophic climate change (http://www.bloomberg.com/news/2013 -02-14/the-most-influential-climate-study-few-people-know-about.html, http://www.rolling stone.com/politics/news/global-warmings-terrifying-new-math-20120719, and https:// www1.ethz.ch/iac/people/knuttir/papers/meinshausen09nat.pdf).
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