Global Warming, Part 2: Impacts, Adaptation, and Mitigation

Transcription

1 C H A P T E R 16 Global Warming, Part 2: Impacts, Adaptation, and Mitigation Learning Objectives After reading this chapter, students should be able to: Understand how changes in greenhouse gases may affect sea level Understand some of the impacts of global warming on ecosystems, particularly the different effects on C 3 and C 4 plants Know the advantages and disadvantages to policies that slow the production of greenhouse gases. Know what the Kyoto Protocol was about. Propose and defend policies (which may include inaction) to deal with anthropogenic global warming Understand some alternative mechanisms for producing electricity, including wind, solar, geothermal, tidal, and nuclear power Know what the term geoengineering means Understand the terms carbon capture and storage and carbon sequestration Understand the difference between a carbon tax and direct CO 2 emission regulations (Note: Although it is not mentioned in the text, one should also make sure the students understand the cap-and-trade legislation that is in place in Europe and has been proposed in the U.S. Congress.) Realize the problem of global warming can be evaluated using a cost-benefit analysis Understand why the results of cost-benefit analyses depends heavily on the amount of economic discounting. Know the difference between the approaches of economists William Nordhaus and Nicholas Stern Become familiar with the concepts of international and intergenerational equity Review Questions 1.) What processes contribute to increases in global sea level, and by how much has it gone up in the recent past? Sea level increases when ice on land melts and when seawater expands as it warms (thermal expansion). Thermal expansion has accounted for most of the observed 20-cm increase in sea level over the last 130 years. The land ice that is easiest to melt is that trapped in mountain glaciers. Fortunately, there is only about half a meter of equivalent sea level rise in such glaciers. The polar ice sheets contain much more water (6 m for Greenland, ~70 m for Antarctica), but this will take much longer to melt. 124

2 2.) Why is predicting future sea level change such a tricky task? It is difficult to predict future changes in sea level because the effects of global warming on the melting of continental glaciers are not well constrained. As the global climate warms, some ice sheets such as the one over Greenland should shrink, whereas others such as the one over East Antarctica may grow. The majority of the Earth s ice is locked up in these large ice sheets, so the impacts they could have on sea-level through glacial surges, growth, and melt-off are large. 3.) How are changes in climate predicted to affect natural ecosytems, including forests and insects? C 3 plants, which cannot photosynthesize at low CO 2 concentrations, are more sensitive to changes in CO 2 concentrations. Therefore, increasing CO 2 concentrations could lead to preferential growth of C 3 plants (which include most trees). C 4 plants, including tropical grasses, corn, and sugarcane, will not be greatly affected by higher CO 2 levels. As the climate warms, some insects that are currently confined to warm, tropical climates (e.g., the Anopheles mosquito which carries malaria), may expand their ranges poleward. The potato leafhopper is a crop pest that may expand northward into the United States Midwest. 4.) What are some of the predicted effects of global warming on human populations? Dry areas, such as the U.S. Southwest, are likely to experience more frequent droughts. The disappearance of mountain glaciers could threaten water supplies for some people. People living along or near coastlines may be displaced if sea level rises, potentially leading to refugee issues from low-lying countries like Bangladesh. Agriculture may be adversely impacted, particularly in regions that are already susceptible to droughts or that are already very warm. 5.) What provisions did the Kyoto Protocol make to slow global warming, and why did the United States decline to sign it? The Kyoto Protocol called for developed nations to cut back CO 2 emissions to 5 percent below 1990 levels by the year It was signed by 182 countries but not by the U.S. The reasons for the U.S. refusal to sign were numerous, but one of them was that developing nations like China and India were not required to take action. (Also, the emissions cuts would have been more severe in the U.S. than in Europe or Russia, because the U.S. economy had expanded faster since 1990.) 6.) What role can energy conservation play in combating global warming? Energy conservation can play a major role in combating global warming by reducing the need for energy. However, by itself, it cannot solve the global warming problem, because it is probably not possible to reduce energy 125

3 consumption by the amount (~85%) that we would need to in order to stabilize atmospheric CO 2 at some reasonable level, such as 450 ppm. Energy conservation could be encouraged by imposing a carbon tax, which would make fossil fuelproduced energy more expensive. 7.) What are some alternative energy sources that might be used to replace fossil fuels? Alternative sources for producing electricity include wind, solar, geothermal, tidal, and nuclear power. Oil could eventually be replaced by using biofuels such as ethanol (although corn-based ethanol is not a practical solution, as it requires too much energy to produce, and because it ties up land that might otherwise be used for food production). 8.) How can carbon capture and storage be used to burn coal in an environmentally safe way? Carbon capture and storage, or carbon sequestration, works by capturing CO 2 at the point where it is being produced (power plants). The CO 2 is then liquefied and pumped into underground reservoirs. If sufficient reservoir capacity can be found, and if other potential environmental problems such as contamination of groundwater can be avoided, then this technology might allow us to continue to burn coal without raising atmospheric CO 2 levels. 9.) What are some ways in which Earth s climate might be geoengineered? Proposed geoengineering solutions include shooting sulfate aerosols into the stratosphere and spraying seawater mist into the lower troposphere. Both of these techniquies could potentially cool the Earth by increasing its albedo. An additional geoengineering technique, the solar shield, will be discussed in Chapter ) What do economists mean by the term cost-benefit analysis? Cost-benefit analysis refers to the technique of weighing the costs of a given project or policy against its perceived benefits. It is a standard procedure used to analyze virtually all large industrial projects. 11.) What role does economic discounting play in cost-benefit analyses of global warming? If one adopts a high economic discount rate, then damages that are incurred in the distant future are strongly downplayed. Because global warming is predicted to occur over a time span of several centuries, even a relatively small discount rate can cause future damages to have little effect on one s analysis. 126

4 12.) What specific differences in global warming policy are advocated by William Nordhaus and Nicholas Stern? Nordaus uses a much higher economic discount rate in his analysis than does Stern. Hence, Nordhaus advocates a relatively small carbon tax, whereas Stern advocates a much larger one. Both economists believe that a tax on carbon would be the most efficient way to push society into reducing CO 2 emissions. Critical-Thinking Problems 1. Write a 2-3 page, typewritten, double-spaced essay on the following topic: Should the world collectively take immediate action to limit CO 2 emissions? If so, what steps should be taken in the U.S. and abroad to deal with this issue? Is nuclear power an acceptable option for producing electricity, or should we rely on renewable energy resources such as wind and solar power? Should we impose a carbon tax in the U.S.? Should developing nations such as China and India be required to cut emissions, as well? If so, how might they be induced to do so? If immediate action is not warranted, what might be the best ways to deal with the anticipated effects of global warming? Do any of the proposed geoengineering solutions appear viable? In short, what would you do about global warming if you were President of the United States? Obviously, there is no correct answer to this question, as it asks for the student s opinions on various matters. Here is what the authors of this textbook think: Yes, we should immediately seek international treaties to limit CO 2 emissions. The best way to reduce emissions in this country, and worldwide, would be to impose a carbon tax. This tax could be small at first, so as not to shock the economy, but it would increase over time. It could be made revenueneutral by returning some of the money as income tax rebates, although it would be prudent to invest some of the money in alternative energy sources and in public transport. Yes, nuclear power needs to be part of the mix if we hope to significantly reduce fossil fuel use over the next few decades. Yes, developing countries, especially China because it is now the world s leader in CO 2 emissions, need to cut their emissions as well. Diplomacy is the best way to convince other countries to reduce their emissions, but economic pressure might eventually be needed. At present, none of the proposed geoengineering solutions looks viable. Carbon capture and storage deserves to be thoroughly investigated, but we (JK, at least) are worried about issues such as groundwater contamination and leakage. Resource Guide Video/Film: Warnings From the Ice 127

5 The global climate naturally cycles between warmer and colder periods. Recent climate changes, however, have caused scientists to wonder whether these alterations are part of the natural cycle or created by human activity. The Antarctic ice may hold some answers. Each year scientists have about a 40-day window in January and February to visit this remote continent and collect data. By analyzing tiny bubbles of air trapped within ice cores and monitoring massive ice sheet movement, researchers glean clues about past global climates and work to predict future conditions. This NOVA program follows scientists as they battle the extreme Antarctic weather to gather data they hope will reveal new insight into the nature of global climate change. NOVA (PBS) What s Up With the Weather? The overwhelming majority of scientists agree: earth's temperature has risen during the past century. But is it due to man's use of fossil fuel energy? And if so, how can we prevent the catastrophic results that some scientists predict if global warming continues? In "What's Up with the Weather?" NOVA and FRONTLINE join forces to investigate the science and politics of one of the most controversial issues of the 21st century: the truth about global warming. NOVA (PBS) The Greening of the Earth This video argues that global warming is good for the environment it is an argument put forth by the Greening Earth Society. It is good to show students this video in conjunction with another video such as Warnings From the Ice in order to allow them to see multiple sides of the global warming debate. Greening Earth Society Websites: Greening Earth Society s home page: The Intergovernmental Panel on Climate Change (IPCC), which most consider to be the consensus view of the scientific community on global warming, has the following website: 128

6 The Union of Concerned Scientists, a group that seeks to examine environmental problems from a scientific standpoint, has their hope page at the following address: The United States Environmental Protection Agency has the following page on global warming: 129