4 ( I YY 1) I - 10
Greenhouse Gretchen Ctwter for Cotuerrution
economics: Learn before you leap C. Daily, Paul R. Ehrlich, Harold and Anne H. Ehrlich Biology. Department Stanford,
of Biologiccz/ Sciences, Stanford
CA 94305-5020, USA
In virtually no area of the human enterprise is there more uncertainty than in matters of national defense. How well armed, trained, allied, clever, and persevering an aggressor might be is often uncertain. Moreover, the nature of an attack - the direction of and with what weapons and strategy a strike might be made - is normally deliberately concealed. In response to this great uncertainty, the United States has military bases around the world, nuclear submarines patrolling the remotest parts of the oceans, missiles poised to strike against any land or airborne target, and military satellites orbitin g the entire planet. Thousands of highly trained intelligence officers filter through the minutia of activities of perceived enemies and prepare elaborate contingency plans. The U.S. has carefully negotiated, verifiable international arms control treaties. Finally, it has developed the most advanced and sophisticated weapons and communications technology in the world to serve these functions. The cost of this form of military security currently consumes about a third of the United States’.federal budget. Indeed, the U.S. has spent in the last decade alone more than 1.5 trillion (1012> dollars to build up an arms apparatus against an enemy whose chance of attacking the U.S. in the last quarter century was never rated higher than about 3%. Now consider the stance of the current U.S. administration on global warming. Nearly every sector of the American economy could be adversely affected by climatic change, and nothing short of our national security and quality of life may be at stake. Most climatologists believe the chances of unprecedented climate change are at least 50%. Yet, offering as justification the uncertainty in timing and location of ‘the strike’, the Bush administration is doing virtually nothing to prepare a defense against this threat. 0921~8009/91/$03.50
0 1991 - Elsevier
B.V. All rights reserved
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Monitoring atmospheric and climatic changes and furthering understanding of global change are badly underfunded endeavors that receive less than one three-hundredth of the support pumped into the military. Furthermore, many ‘no regrets’ precautionary measures (ones that would actually be economically, politically, socially and environmentally beneficial even in the improbable case that global warming proves benign), such as improving efficiency in energy use, are not actively encouraged. Though the United States could be greatly affected by the behavior of other nations with respect to the atmospheric global commons, it has stalled international efforts to forge agreements aimed at slowing or preventing climate change. The uncertainty about the pace and regional impact of climatic change is only a minor factor hindering the development of policy on this issue. Much of the delay in action results from faulty methods of analysis, from undervaluation of services provided by natural ecosystems that would be disrupted or terminated by the warming, from the application of high discount rates to social, economic, and ecological damages to be incurred in the future, and from the delusionary effect of the lag time between initiating a given climatic change and its actual manifestation. What are the benefits of maintaining the status quo in policy? William D. Nordhaus attempted to answer this question in a recent article (Nordhaus, 1990) in which he reveals a fundamental misunderstanding of the functioning of natural systems and the limitations of humanity’s ability to control those systems. Basically Nordhaus does not recognize: (1) The dependence of the economy upon free services provided by healthy natural systems. (2) That it is questionable whether the scale of activities anticipated by many policy makers, involving a 5 to lo-fold increase in economic activity (WCED, 1987), can be maintained over the long term under any sensible set of technological assumptions. (3) That the principal constraints on the human enterprise are environmental, and that few of the critical ones can be relaxed by large-scale technological interference. (4) That the enhancement of the greenhouse effect could lead to an unprecedented disruption of civilization, a consequence that would be irreversible on any time-scale of interest to society (NAS, 1987; IPCC, 1990). (5) That what he terms ‘panicky eco-action’ - a substantial reduction in the rate of anthropogenic greenhouse gas emissions - is precisely what is called for as the result of sober risk analyses.
Global warming is much too tame a description for the likely results of substantial increases in the atmospheric concentration of greenhouse gases. The equivalent of a doubling of CO, over preindustrial levels is expected to cause an increase of 1.5 o C to 4.5” C in Earth’s mean surface temperature (IPCC, 1990). Nordhaus (unpublished) dismisses this increase as trivial because most people experience much greater temperature fluctuations daily. But fluctuations in temperature during a given day and gradual changes in the average temperature of the planet are entirely different phenomena. At the peak of the last ice age, the mean surface temperature of Earth was ‘only’ 5 OC cooler than it is now. But then. an ice cap a mile or more thick covered most of Canada and parts of both Eurasia and the northern United States (including all of Manhattan) (Schneider, 1989). Not only is the magnitude of climate change caused by the buildup of GH gas concentrations potentially great, but the estimated pace of change is ten to 50 (or more) times faster than even the unusually high natural rate of change that ended the last glaciation (IPCC, 1990). ASSESSMENT
OF THE IMPACTS OF GLOBAL WARMING
In the following discussion, we assume that the warming from 1990 to 2070 will be on the order of 2.5 ‘C and that some of the regional changes jointly predicted by various climate models actually occur. While considerable scientific uncertainty remains about the precise nature of regional changes, there appear to be better than 50-50 odds that such changes will occur. Food production.
Nearly every aspect of agriculture is likely to be affected by global warming. More than half of humanity’s food is grown in regions that could undergo substantial declines in soil moisture: central North America, Europe, the Soviet Union, and China (FAO, 1990). At least in the short term, losses in some areas are unlikely to be offset by gains in others because of overall production declines sure to be suffered during a prolonged adjustment to shifting climate belts. In addition, it is unlikely that the high productivity characteristic of regions like the United States grain belt can be achieved on the thin, acidic soils of many northern areas like the Canadian shield, should favorable temperature and precipitation regimes be established there (Brown and Young, 1990). Since CO, is generally a limiting factor for photosynthesis, hopes have been raised that the rise in CO, concentrations would result in increased crop yields. Nordhaus translates this possibility into the bland assertion
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that *‘the associated fertilization effect [of CO: on agriculture] will probably offset any climatic harm in the next century.” Though increases in CO, concentration may enhance growth of some crops, weeds and pests may benefit as well (Gribbin, 1990; Lincoln and Couvet 1989; Lincoln et al. 1986; but see Fajer et al., 1989). Moreover, perhaps half the warming ahead will be caused by trace gases other than CO, which have no positive effects. on plant growth. It would not be sound policy to count on the potential benefits of COZ fertilization to ameliorate the impacts of global warming on agriculture, especially with a world food situation as marginal as today’s. Results of a recently published computer model (Daily and Ehrlich, 1990) suggest that even if global warming causes favorable climatic events that enhance agricultural production, a severalfold increase in hunger-related deaths (over current levels) may not be preventable if growth in population outpaces that in food production. Currently, an estimated 10 million people die of hunger and hunger-related disease each year (Dumont and Rosier, 1969; WHO, 1987; see discussion in WRI, 1987). Nordhaus dismisses the effects of global warming on the production of food and timber as trivial, arguing that these economic sectors account for barely 3% of America’s GNP. Yet the contribution to GNP fails to measure the importance of these sectors in geopolitics, trade relations, and international security - to say nothing of simply staying alive. In other words, their percentage of GNP is not a measure of the full value of agriculture and forestry to the economy. Imagine the situation if the U.S. became dependent upon foreign food imports as it already is on foreign oil. Perhaps Nordhaus’ comment was tongue-in-cheek, an allusion to the old saying, “economists know the price of everything and the value of nothing.” Coastal land security. A global sea-level rise of roughly 0.2-0.7 m (and possibly considerably more) by 2070 may occur as a result of thermal expansion of the oceans and partial melting of glaciers and polar ice caps (IPCC, 1990). Increasing population and economic pressures have already led to widespread degradation of coastal areas and to local land subsidence. Taking into account the effects of storm surges and saltwater intrusion into rivers and aquifers, such a sea-level rise could threaten a substantial portion of global cropland and the homes of millions of people. The cost of protecting coastal areas worldwide from even such a small rise would be so expensive that it’s hardly worth calculating. Low-lying developing countries, the most vulnerable to loss of productive cropland and freshwater supplies, are the least able to protect themselves. Furthermore, they are the parties least responsible for causing global warming (relative to the consequences they face).
on nnrru-al ecosystems. The same kinds of impacts that rapid climate change would inflict on agricultural ecosystems would also affect natural ecosystems. Marshes and coral reefs are biologically highly productive. and both are already seriously threatened. Coastal wetlands may be unable to migrate inland at the pace set by rising sea-level, or may be prevented from migrating at all by dikes, railroad tracks, shopping mails or other impediments. Coral reefs, moreover, are exceptionally sensitive to changes in water temperatures. Further diminution of these coastal and marine ecosystems through global warming would have serious deleterious impacts on many valuable coastal and deep-sea fisheries (the latter often depend upon coastal wetlands and estuaries for nursery grounds and food supplies). Should natural terrestrial ecosystems and their constituent populations be decimated by global warming, humanity would be adversely affected in several important ways. Aside from the aesthetic value of wild species, we derive enormous economic benefits from biodiversity. Agricultural crops are regularly improved with genetic material from wild populations that enhances resistance to pests or tolerance of drought and salinity, among other traits. More than a third of all pharmaceuticals and numerous other useful substances are derived from wild plants, animals, or microbes. More importantly, civilization depends on services that intact ecosystems provide on such a grand scale and in such an intricate way that there is no possibility of substituting for them. These services include amelioration of regional climates, regulation of the hydrological cycle, creation and maintenance of soils, cycling of nutrients, disposal of wastes, control of potential pests, pollination of crops, and provision of a vast genetic library upon which all organisms, including human beings, depend to adapt to future changes. The extent to which such services would be disrupted by rapid climate change is unclear, but it would certainly be prudent to avoid running the experiment (Ehrlich and Ehrlich, 1981). The elimination of natural populations and extinction of species is akin to popping rivets out of an airplane wing. While the wing might continue to perform minus a few rivets, no one with any sense would knowingly fly an aircraft undergoing such modification. Impncts
Hwmzn encironments. The likely manifestations of global warming on human environments include an increased frequency of extremely hot days, worsened water supply problems in some regions, and the spread of diseases now confined to the tropics. Heat waves cause health problems, especially for the old and very young, and economic losses as well. Water shortages, already causing trouble in places as disparate as the U.S. West and the Himalayan foothills of India, could become acute in many areas.
Over 200 river systems are shared by two or more countries. Regional conflict remniscent of the 1967 Arab-Israeli war (largely fought over water) could be sparked over claims on freshwater sources where scarce supplies are further reduced (Gleick, 19S9). Numerous parasitic and other diseases, such as malaria, leishmaniasis, schistosomiasis, various intestinal worm infestations, yellow fever, and dengue, are currently restricted in range primarily by temperature. Very small increases in yearly mean temperatures could permit significant range extensions of tropical diseases into Europe, North America, and elsewhere (Haines, 1990). Energy and industry.
The traditionally tight coupling between industrial growth and energy use is relaxing with improvements in efficiency, particularly in Japan and the EEC. Nonetheless, international responses to global warming, already beginning, clearly will affect future industrialization paths, especially in developing countries. Fully 78% of the world’s energy is derived from combustion of fossil fuels, a process that not only releases large amounts of CO,, but also causes emissions of methane and nitrous oxide, two other important GH gases. Production and use of energy contribute about 60’2%of all anthropogenic greenhouse gas emissions (Flavin, 1989). Diverse industries could also be directly impacted through significant changes in water availability. Water is a critical industrial resource, used for discharge of effluents, cooling and other processes, and transport. The United States is the greatest single contributor The global commons. to global warming, and in that capacity influences the fate of every other nation on the planet. Even so, the inevitable increases in GH gas emissions that would accompany attempts of developing countries to realize industrialization goals through modest increases in per-capita energy use could cause the U.S. to regret its recalcitrance in the development of a global atmospheric policy. The world is now so interconnected, politically, economically, and especially physically through the atmosphere, that for the rich to count on a lifeboat escape from the consequences of a buildup of GH gases would be sheer folly. GEOENGINEERING
Human beings have always strived to control their environment for their own benefit and have enjoyed considerable success. As the human popula-
tion has grown, however. programs for modifying the environment have vastly increased in scale, beyond humanity’s ability to fully understand or control their impacts. This has repeatedly resulted in unforeseen negative environmental consequences. The Egyptian Aswan High Dam project typifies cases where good intentions have had disastrous results. Construction of the dam reduced eastern Mediterranean fish populations, led to soil impoverishment (because it prevented the regular flooding and silt deposition onto agricultural land in the Nile delta), and caused an explosive outbreak of schistosomiasis. With a little foresight, alleviating problems that the dam failed to solve (bringing the E gyptian population into balance with its agricultural productivity, for example) would have had higher returns. The catastrophic effects of engineered changes in the hydrologic system on the Aral Sea area of the USSR and on Florida’s Everglades National Park are other examples. Now that the scale of the human intervention in the atmosphere is so large that climate stability is threatened, possibilities for modifying the global environment to counteract expected changes are being discussed. Nordhaus (1990) argues that control of the climate through massive engineering projects would “probably be far more cost-effective than shutting down the world’s power plants.” This assertion suggests that these extreme cases are the only alternatives. It also wildly overestimates human understanding of the functioning of earth systems, which is still very primitive. The information required to develop successfully any massive engineering solutions to global warming will remain elusive for some time (if not forever) because of the extraordinary complexity of those systems. Furthermore, the possibility that such geoengineering could produce more unpleasant surprises like the Antarctic ozone hole must be seriously considered. Recently proposed schemes for engineering the biosphere would be high-risk ventures of unprecedented magnitude entailing very large costs and producing uncertain results, including incalculable environmental impacts. The suggested fertilizing of the ocean to enhance CO, uptake would cost billions and has the potential of making the ocean anoxic over time. Reducing solar input with space mirrors or by launching stratospheric dust or aerosols are also multibillion dollar schemes that have no guarantee of meeting target climate amelioration values. Missing the targets would have enormous consequences for agriculture and for the earth’s capacity to support its billions of human inhabitants. Indeed, the consequences of large-scale environmental interventions, given the present state of knowledge, could be more detrimental than the perturbations the interventions were intended to ‘fix’.
TO THE THREAT
In the face of such uncertainties, what should social responses be to the potential global warming ? Considering the severity of possible consequences and how people ordinarily insure themselves against other threats, we believe immediate action is required. The present accumulation of GH gases in the atmosphere has already committed the planet to a warming of 1” C to 2’ C (Abrahamson, 1989). Even though the effects of global warming may not unequivocally manifest themselves for a decade or more, there is a real cost of waiting to abate GH gas emmissions. Several ‘no-regrets’ measures would serve as insurance and would provide net social and economic benefits beyond slowing global warming. These include increasing energy efficiency, developing alternative energy sources, halting deforestation, accelerating reforestation, and curtailing population growth (Holdren, 1990). The U.S. has a great deal to gain and very little to lose in participating in international efforts to abate global warming. Elementary calculations of the enhancement of the greenhouse effect by even limited coal-fueled development in China and India make this crystal clear (Ehrlich and Ehrlich, 1990). Improvements in energy efficiency carry many benefits. including saving money, preserving infrastructure, and abating sources of serious pollution other than GH gases. Development of alternative energy sources is imperative, not only because of the dangers of continued high CO, emissions, but also because of the rapid depletion of oil resources and the increasing problems of dependence upon Middle East oil. If costs of military preparedness and intervention were factored into the cost of each barrel of oil from the Persian Gulf, other energy options would appear even more attractive. If all the social costs of fossil fuel use were internalized, the advantages of deploying a solar-hydrogen technology would likely appear overwhelming. A significant fraction of the forests that blanketed the earth just 200 years ago have been cut or burned down. Stopping deforestation from the Tongass to the Amazon could substantially reduce the release of CO, into the atmosphere. Reforestation would remove some CO, and sequester it in wood while the young trees were growing. Restoring forest to denuded areas offers a one-shot gain, but it could help delay the onset of climatic change, giving societies more time to adjust. Reforestation would have numerous additional benefits, including local and regional regulation of the hydrological cycle (reducing the frequency of both floods and droughts), local climate amelioration, erosion control, and establishment of a sustainable resource for fuelwood and other products. Finally, if any attempt to deal with greenhouse warming is to succeed,
measures must be taken to develop the socioeconomic conditions that favor reductions in human fertility. The connections between greenhouse gas emissions and human numbers are tight. and it is naive in the extreme to believe that severe climatic impacts can be avoided if those numbers grow ad libidum (Ehrlich and Ehrlich 1000). Now is the time for action; each moment of delay increases the chance that changes will be catastrophic while diminishing the options for effective response. Despite scientific uncertainty, more than enough is known to establish the need for response as well as about what can be done. It’s up to the voters and policy-makers to do it. ACKNOWLEDGEMENTS
We are grateful for the helpful comments on an earlier draft of this manuscript provided by Lawrence Goulder, Partha Dasgupta, Peter Vitousek, and three anonymous reviewers. CONCLUSIONS
Though global warming could adversely affect the ecological underpinnings of virtually every sector of the American economy, the United States has made no effort to slow or prevent its onset. The uncertainties associated with climate change have served as the primary excuse for not taking precautions against this threat. This position has been reinforced by a faulty assessment of the possible impacts of climate change: the undervaluation of services provided by natural ecosystems; the application of high discount rates to future costs of damages; and a misplaced confidence in human ability to effect desirable changes in little-understood natural systems. The latter is reflected in the preference for massive intervention in global biogeochemical systems over initiating comparably small changes in relatively well-understood aspects of the economy. This is especially unfortunate since mistakes made with natural systems are much more likely to prove irreversible. REFERENCES Abrahamson. D.. 1989. Global warming: the issue. impacts, rcsponscs. In: D. Abrahamson (Editor), The Challenge of Global Warming. Island Press. Washington. DC. Brown, L.R. and Young. J.E.. 1990. Feeding the world in the nineties. In: L.R. Brown. A.B. Durning. H.F. French. C. Flavin. J.L. Jacobson. M.D. Lowe. S. Postel. Xl. Renner, L. Stark and J.E. Young (Editors). State of the World 1990. Worldwatch Institute. Washington. DC. pp. 59-78.
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Daily. G.C. and Ehrlich, P.R.. 1990. An exploratory model of the impact of rapid climate change on the world food situation. Proc. R. Sot. London B, 241: 232-244. Dumont. R. and Rosier. B., 1969. The Hungry Future. Praeger, Frederick. NY. pp. 3-l-35. Ehrlich. P.R. and Ehrlich, A.H.. 1981. Extinction. Ballantine. New York. Ehrlich. P.R. and Ehrlich, A.H.. 1990. The Population Explosion. Simon and Schuster, New York. Fajer, E.. Bowers, M. and Bazzaz. F.. 1989. The effects of enriched carbon dioxide atmospheres on plant-insect herbivore interactions. Science, 213: 1198- 1200. FAO, 1990. Annual Production Yearbook. Vol. 43. UN Food and Agriculture Organization. Rome. Flavin. C.. 1989. Slowing global warming: a worldwide strategy. Worldwatch Pap. 91, Worldwatch Institute, Washington, DC. Gleick, P.H., 1989. Global climatic changes and geopolitics: pressures on dcvelopcd and developing countries. In: A. Borer, S. Schneider and J. Duplessy (Editors), Climate and Geosciences, Kluwer, New York, pp. 603-621. Gribbin. J.. 1990. Britain must learn to farm the greenhouse. New Scientist, February 2-1, p. 28. Haines, A.. 1990. The implications for health. In Global Warming: The Greenpeace Report. Oxford University Press, Oxford, UK, pp. 149-162. Holdren. J.P., 1990. Energy in transition. Sci. Am., 263: 156-163. lPCC (Intergovernmental Panel on Climate Change). 1990. Climate Change: the IPCC Scientific Assessment. Edited by J.T. Houghton, G.J. Jenkins and J.J. Ephraums. Cambridge University Press, Cambridge, UK. Lincoln, D. and Couvet, D., 1989. The effect of carbon supply on allocation to allelochemicals and caterpillar consumption of peppermint. Oecologia (Berlin). 78: 112-l 14. Lincoln, D.. Couvet. D. and Sionit, N., 1986. Response of an insect herbivore to host plants grown in carbon dioxide enriched atmosphere. Oecologia (Berlin), 69: 556-560. NAS (National Academy of Sciences), 1987. Current Issues in Atmospheric Change. National Academy Press, Washington, DC. Nordhaus. W.D., 1990. Greenhouse economics: count before you leap. The Economist, July 7, p. 31. Nordhaus. W.D., unpublished manuscript. To slow or not to slow: the economics of the greenhouse effect. Yale University, New Haven, CT. Schneider. S.H., 1989. Global Warming. Sierra Club Books, San Francisco, CA. WCED (World Commission on Environment and Development), 1987. Our Common Future. Oxford University Press, Oxford, UK, xv+383 pp. WHO (World Health Organization), 1987. International Health News, September. WRI (World Resources Institute). 1987. World Resources 1987. Basic Books, New York, pp. 18-19.