Issues in Science and Technology, Online A Publication of National Academy of Sciences National Academy of Engineering Institute of Medicine University of Texas at Dallas
  • Home
  • Back Issues
  • Search


The Global Environment

ROBERT M. WHITE

Climate Science and National Interests

The scientific case for action to reduce greenhouse gas emissions is perceived to be changing, but the political barriers remain daunting.

Scientific developments and a change in U.S. policy have shifted the terms of the discussions that will take place in June 1997 at the conference of parties to the Framework Convention on Climate Change. Growing scientific confidence about the role of human activity in global climate change and the willingness of the United States to consider binding reductions in greenhouse gas emissions will force the conference participants to address the issue of climate change more directly and to consider immediate and far-reaching measures. But this is not a problem that can be solved by science alone. Reaching agreement on targets for greenhouse gas emission reductions for the period beyond the turn of the century will be difficult because of the deep-seated differences between rich and poor nations, between coastal countries and fossil-fuel rich nations, and between various other factions.

When the participating nations met in Berlin in March/April 1995, they agreed on emissions limitations for the decade 1990-2000 that would limit global greenhouse gas emissions in the year 2000 to the level that prevailed in 1990. However, all signs indicate that the world will miss its goal by a wide margin. In fact, U.S. officials believe that only the United Kingdom and Germany are on track to meet their targets.

What's more, all parties recognize that even if they were to reach their goal for the year 2000, it would not stabilize the climate but only stabilize the rate of increase of atmospheric carbon dioxide concentrations and presumably, to a reasonable approximation, the rate of increase of the average surface temperature. At the levels of greenhouse gas emissions of 1990, some 6 billion tons of carbon would be emitted to the atmosphere each year, increasing the carbon dioxide concentration in the atmosphere annually and thus adding to the radiative forcing and presumably to the continuing rise in global temperature.

Stabilization of the climate in its present state, as expressed by the global surface temperature, would require reductions of 60 to 80 percent in greenhouse gas emissions-an unrealistic goal for a global economy that is fundamentally dependent on coal, oil, and gas for its viability in the foreseeable future. Influenced by recent scientific reports and aware of the failure of voluntary efforts to achieve emission reductions, the United States has now indicated that it will seek a binding agreement on emission caps and timetables. Timothy Wirth, undersecretary of state for global affairs, announced the new U.S. policy in July 1996: "The United States recommends that future negotiations focus on an agreement that sets realistic, verifiable, and binding medium-term emissions targets . . . [they] must be met through maximum flexibility in the selection of implementation measures including use of reliable activities implemented jointly and trading mechanisms around the world."

The delegates preparing for the 1997 conference of parties to the climate treaty are on a crash course with reality. They must plot a course that recognizes the growing certainty among most scientists that human actions are changing the global climate, as well as the political divisions that threaten to unravel any attempt at coordinated action. And once they confront the limits of what can be done to slow global climate change, they must face the challenge of what to do next.

New science

The coming policy debate will be particularly contentious because negotiators will have to deal with the fact that scientific understanding of the climate warming process has changed significantly since the 1990 international assessment by the International Panel on Climate Change (IPCC) of the World Meteorological Organization and the United Nations Environment Program. The scientific findings reflected in the 1996 report will necessitate changes in the negotiating positions of many countries. Although a scientific debate still rages about it, the most important new finding in the summary report is that comparisons between the forecast and observed patterns of global surface temperature convinced the panel that "the balance of evidence suggests that there is a discernible human influence on global climate." This is a significant change in conclusions.

Until now, there has been a reluctance on the part of the scientific community to claim that the temperature rise observed over the past century is due in part to human activity. The prevailing view has been that the observed global surface temperature rise was within the limits of natural climate variability. Some scientists not involved in the IPCC process still maintain that there is not enough evidence to support such a statement, and an international group of dissenting scientists has warned against premature action on global warming. But the clear implication of the IPCC conclusion is that serious consideration must be given to actions that influence human activities so that global reductions of greenhouse gas emissions can be achieved.

The new report also devotes more attention to long-term projections of temperature changes to be expected by the year 2100. Although the 1990 report also made projections for the end of the next century, it was principally concerned with the temperature around 2030, the year in which greenhouse gas concentrations are projected to be double the present levels. The 1996 IPCC report expects smaller global average temperature increases than were being projected five years ago. The best estimate for the year 2100 is for a global surface average temperature increase of 2 degrees centigrade, with a range of 1 to 3.5 degrees centigrade. The 1990 report projected a 3-degree-centigrade increase with a range of 1.5 to 4.5 degrees centigrade. In short, new projections indicate more gradual and smaller increases in temperature.

At the high end of the range of projected warming, a 3.5-degree-centigrade increase in surface temperature over a century represents a rate of change outside recent historical experience and implies major changes in climate conditions. At the lower end of the range, 1.0 degrees centigrade, the climate warming is not severe and it is likely that humanity will find little difficulty in adjusting, although the effects on specific ecosystems remain uncertain. Because the actual global average surface temperature can fall anywhere within this range, negotiators are still left with very large uncertainties about the extent and severity of actions that will need to be taken by the global community.

A further important change in the most recent scientific results is that a much closer correspondence between the temperature increase over the past century and that reproduced by the newest and more complete mathematical models of the global atmosphere and oceans has been achieved. The models, which are the basis for projections of climate change that have been developed during the past half decade, give much more realistic simulations of atmospheric conditions. Previously, mathematical models yielded projections of temperature that were much higher than the observed temperature rise. This has been a great puzzle and, for those who placed little credence in the temperature projections, a source of legitimate criticism of the models and the policies that were based on them. But here finally are projections that look much like the observed record of the global average surface temperature, thus lending support and credence to the calculations based on them and the policies that flow from the calculations.

The new element that changed the nature of the calculations was the incorporation into the mathematical models of the effects of aerosols. Aerosols are small solid or liquid particles that form in many ways-most importantly as sulfates formed from sulphur dioxide emissions in the burning of fossil fuels but also from volcanoes and dust. Unlike carbon dioxide, aerosols are not evenly distributed throughout the global atmosphere but are concentrated over industrial areas and deserts. As particles, however, they act in an opposite manner from greenhouse gases. They tend to cool the atmosphere by reflecting sunlight into space. When the effects of aerosols are introduced into the mathematical models, as they have been in those considered in the 1996 report, they partially counteract the warming effects of greenhouse gases and thus result in predicted rates of warming that are lower and slower than those of previous mathematical models. According to a recent report of the National Research Council, "global models suggest that sulphate aerosols produce a direct forcing in the Northern Hemisphere of the same order of magnitude as that from anthropogenic greenhouse gases but opposite in sign."

The likelihood is that no matter how successful the negotiations are humanity ill still be faced with the prospect of a changing climate.

Same old politics

As consensus is building in the science underlying the policies that the parties to the conference will seek to adopt in 1997, there has been a hardening of political positions among the developed and developing countries. Island nations and some coastal nations, fearing that their territories may be inundated by the rise in sea level associated with global climate warming, are understandably strongly in favor of immediate action. They seek agreements on emission caps and time tables. Countries dependent on fossil fuel production and use, such as the oil-rich Persian Gulf states, and coal-dependent countries such as China and India are opposed to such agreements.

This Balkanization of political interests in the negotiating process is superimposed on the longstanding difference of views between the industrialized and developing nations on how to proceed. This fault line between negotiating positions is almost irreparable. Only vast economic and resource concessions to the third world by the industrialized countries can bridge this discontinuity. On one side of the fault line are the developing nations that are committed to the view that it has been the industrialized nations who have up until now caused the global increases in greenhouse gas concentrations in the atmosphere. The developing countries are now industrializing and need greater amounts of energy, largely from fossil sources; they do not intend to let their economic growth be slowed by restrictions on energy use.

But all projections of economic and population growth and associated increases in energy usage conclude that any realistic approach to constrain greenhouse gas emissions must focus on the developing world because that is where the largest increases are expected to occur. The negotiating position of the industrialized countries, which are prepared to accept restrictions on energy use, stems from the credence that they place in scientific assessments that the projected temperature changes and carbon dioxide residence times have a good probability of being on the high side of expected ranges.

In the view of the developing world, the industrialized North owes the industrializing South an "ecodebt," which should be paid in two ways: The North should bear most of the burden of greenhouse gas reductions, and it should transfer environmental and energy technology to the South on favorable terms so that the energy efficiency of their economies can be increased, thus reducing the emissions of greenhouse gases from their territories. In fact, one of the major achievements of the 1992 UN Conference on Environment and Development in Rio was the agreement to create the Global Environmental Facility to provide funding from the industrialized countries to enable the developing countries to acquire amd introduce environmentally advantageous technologies. Pledges of resources have been substantial but have fallen far short of the aspirations of the developing countries.

Accommodating all these varied interests will not be easy. Strategies that will achieve global emission goals without impeding the economic growth of developing nations abound, but all involve severe penalties on one or another of the parties to the convention. The various strategies are based on models of the evolution and growth of the economies of the world's countries, assumptions about technological trajectories, estimates of rates of population growth, and alternative modes of accommodating all parties. What emerges from the various studies employing such models are scenarios of possible futures that depend fundamentally on the fraction of the total global energy supply that will be met with fossil fuels of various kinds and assumptions about the role that will be played in the energy supply system by renewable and nuclear sources. Assumptions are also made about the rate of increase in the efficiency of energy supply and demand technologies.

The dilemma is now being resolved largely in the political arena. In countries with politically strong "green" movements, governments favor emission caps and timetables for achieving them. They are buttressed by the results of the IPCC assessments. In the United States, where there is a vocal dissenting scientific community and political differences on this issue between the Republican and Democratic parties, a year-long battle looms on how to position the United States for the negotiations. The Clinton administration has stated its policy, but the results of the 1996 election could lead to changes. Other nations will face similar internal debates before the 1997 meeting.

The outcome of the negotiating session will vitally affect not only the energy supply and demand industries but other industries and businesses as well, to say nothing of the effects on agriculture and water resources. The implications go further, for if the threat of an unacceptable climate cannot be addressed, we will certainly be unable to achieve an environmentally sustainable global economy.

An interesting development has taken place within the industrial community as it contemplates these upcoming negotiations. Some parts of the international insurance industry have come to believe that the weather anomalies of the past several years that have caused an estimated $25 billion to $30 billion in global annual losses are out of line with normal climatological expectations. In the United States, hurricane Andrew alone accounted for $15.5 billion in insurance claims. The suggestion that anomalous weather phenomena that have caused great insurance industry losses may be related to climate warming has been implied by some U.S. scientists and publicized in the press. It is not surprising, therefore, that the insurance industry is supporting efforts to arrest the rise in global temperatures. The fossil energy industries, including producers such as the oil, gas, and petroleum companies, and users such as the automobile interests, have always argued for caution before implementing policies to limit fossil fuel use, with some questioning the scientific validity of the climate warming concept.

In this confusing confluence of scientific and political interests, little is understood about the distribution of the climatic and economic effects that must be of central concern to negotiators. The global average surface temperature is but a surrogate measure for the intensity of the climate-warming phenomenon. Any particular global average surface temperature will give rise to nonuniform geographic distributions of high and low temperatures.

Mathematical models are as yet not able to portray the regional and national distributions of temperature or precipitation with any certainty. Negotiators therefore do not know, except to a crude approximation, what the effects of global climate warming will be on their territories. Sea level rises are exceptions because the effects of global climate warming are essentially uniform throughout the world oceans. But these effects are now projected to be smaller than previously thought. In the 1990 report, the IPCC projected approximately a 2-foot rise in sea level by 2100; in its 1996 report, the sea level rise is estimated at about 1.5 feet for the same period. Yet the 1996 estimates have a wide range, from 0.5 feet to more than 3 feet. Again, at the lower end of the range the rise is unlikely to be troublesome for most regions, whereas at the high end of the range the effects would be devastating.

We know little about other distributional effects except on the grossest scale. All projections are for greater warming in the polar than in the equatorial latitudes. This suggests that nations located at higher latitudes will undergo a greater warming at the surface than those in mid-latitudes and in equatorial regions. Because the intensity of the global circulation is driven by temperature differences between polar and equatorial regions, the implication is for a less intense global circulation, which is more typical of warmer seasons in mid-latitudes. Even slight changes in climate can significantly affect climatically marginal regions, but it is not clear, for example, whether arid regions will be exposed to more precipitation or increased desiccation.

The negotiations

Unlike other negotiations where national interests are clear, government representatives will literally be negotiating unknown consequences for their countries. They will have as their goal the stabilization of the present distribution of climate with its advantages and disadvantages for the nations of the world. Climate can be regarded as a resource, conferring advantages on some nations and disadvantages on others. The current climate is advantageous for U.S. agriculture and disastrous for Mongolian farmers. No negotiation, except perhaps for those related to preventing nuclear conflicts, has the potential for such broad societal impacts.

Many of the promising energy options are sufficiently far from commercialization that international collaborative actions might advance their availability.

The economic effects are similarly uncertain. These will depend on the way economic development evolves. Many different scenarios and options are portrayed by mathematical models of the global economy. Even more than the mathematical models that project the physical state of the atmosphere and the oceans, economic models of the global economy are shot through with assumptions and simplifications concerning the course of economic growth. Whereas refinement of mathematical models of the physical environment can be expected to continue to reduce uncertainties, models of the evolution of the global economy may be so distorted by political and economic events as to be projecting the unknowable.

Assumptions are made in the economic models about the trajectories of technological development in moving from fossil to nonfossil fuels and about the growth of population. When these economic and population models are joined with physical models of the atmosphere, oceans, and biosphere, it becomes possible to project the characteristics of future climates. Although these models provide important information on possible futures, they tell us little about how economic effects will be distributed among nations and individuals.

The weakness of the economic models helps explain why even when nations can agree on greenhouse-gas abatement goals, negotiators will find it extremely difficult to agree on how to achieve them. An international regime with the power to promulgate policies and regulations and enforce them would be out of the question. Timothy Wirth has explicitly ruled out the acceptance of such a system by the United States: "As a general proposition, the United States opposes mandatory harmonized policies and measures." Few nations would agree to such an international authority, especially in the face of the uncertain consequences for their economies.

Whatever approaches individual countries adopt, from free market incentives to command-and-control regulatory systems, there would still be the need to allocate greenhouse-gas emission quotas to individual nations. Many policymakers favor the market-based approach of tradeable emission permits, which the United States uses to control sulphur dioxide emissions. When working properly, this system provides tremendous flexibility to those responsible for reducing emissions and takes advantage of market forces to achieve the lowest possible cost of attainment. However, the success of such a concept depends on the initial allocation of emission caps to various countries. Would they be allocated on the basis of population, gross national product, the geographical extent of territory, or some combination of these? Arriving at an equitable formula for allocation of greenhouse gas emission caps would be an extremely difficult task, if doable at all.

Furthermore, because it is the cumulative amount of carbon dioxide emissions over time that governs their effects on climate, negotiators can play with emission limits that vary with time. For example, it has been suggested that emissions in the near term could be allowed to grow rapidly, with serious emission restrictions reserved for the future. To negotiators, this might seem to be a rational approach because it would provide time to verify that the climate is indeed changing before more drastic action is taken. Finally, assuming that negotiators could come to agreement on allocation of greenhouse gas emission caps and schedules to each nation, the individual governments would face the equally difficult task of allocating such caps within their territory and among economic sectors.

Tools for change

The likelihood is that no matter how successful the international negotiations are, humanity will still be faced with the prospect of a changing climate. If the actual temperature increases are at the low end of the projected temperature range, traditional modes of adaptation are feasible. In fact, the actions taken by nations today in the face of existing climate variability would need to be extended only slightly for people to adapt. Human beings live in the most extreme polar and desert regions. Throughout history, humans have adapted to climate variability by planting crops that thrive in different climates, building dams to store water, building coastal defenses against inundations, and adapting clothing and modes of shelter to enable them to exist in almost all climates. Extraordinary changes in these strategies would probably not be needed.

Even if the temperature regime and the implied changes in precipitation occur at the higher end of the projected range, adaptation is still a key way to cope with climate change as its regional and distribution effects become apparent. International assistance could be invoked to deal with the most egregious of these conditions, as indeed it is today in the face of persistent droughts or floods.

It is surprising, then, that missing from the negotiations is any concept of marshaling international action to develop technologies that will be needed for adaptation. Such technologies could provide options for coping with climate changes that might result from greenhouse gas emissions. Central to reducing greenhouse gas emissions are changes in the global energy system. Options are needed for moving to nonfossil energy sources, should this be necessary. Research and development in a wide range of alternative technologies is under way in many countries, and international collaboration has already begun on some of them, such as the development of nuclear fusion through the International Thermonuclear Experimental Reactor.

However, more needs to be done. Many of the promising energy options are sufficiently far from commercialization that international collaborative actions might advance their availability. For transportation, the development of hydrogen as a safe fuel appearsfeasible. For other uses, more efficient energy production by photovoltaics, biomass, wind, and fuel cells seems promising. Even the unthinkable, nuclear fission breeder reactors, might be considered. The fact is that absent efficient new energy technologies to achieve greenhouse emission goals, the negotiators simply will not have the tools necessary to address the problems associated with global climate change.


Robert M. White is a senior fellow at the University Corporation for Atmospheric Research and the Heinz Center for Science, Economics, and the Environment. He is a former chief of the U.S. Weather Bureau, the first administrator of the National Oceanic and Atmospheric Administration, and president emeritus of the National Academy of Engineering.