National Issues in Science and Technology 1993 (1993)

NATIONAL ACADEMY OF SCIENCES

NATIONAL ACADEMY OF ENGINEERING

INSTITUTE OF MEDICINE

A White Paper from the

NATIONAL ACADEMY OF SCIENCES

NATIONAL ACADEMY OF ENGINEERING

INSTITUTE OF MEDICINE

February 1993

The Earth Summit in Rio de Janeiro established global environmental problems as a central challenge in the post-Cold War world. At that event, leaders from 155 countries signed an unprecedented climate change convention intended to reduce or offset emissions of greenhouse gases and thus avoid the threat of excessive global warming. In the months before the Earth Summit, a special panel established by the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine assessed ways of reducing emissions and the preparations needed to cope with climate change if it occurs.¹

Greenhouse warming—a rise in global average temperature due to increasing atmospheric concentrations of greenhouse gases—represents a new kind of global environmental problem that will likely continue to grow in importance. It is universally agreed that atmospheric concentrations of greenhouse gases have increased over the last 100 years and continue to increase due to the burning of fossil fuels, deforestation, and other industrial and agricultural

activities. During the same period, the global surface temperature has increased about one degree Fahrenheit. It is impossible to demonstrate scientifically whether or not this increase in global average temperature is due to increased concentrations of greenhouse gases.

Despite uncertainties, there is widespread agreement that anthropogenicgreenhouse gas emissions will eventually raise the global averagetemperature. Feedback mechanisms and other events such as volcanic eruptions or the emission of tropospheric aerosols can counter global warming, but likely only temporarily. Continued increases in emissions of greenhouse gases have the potential to produce a planet warmer than at any time in human experience. However, the rate of this temperature increase and the implications of warming for various regions are not well known, which makes it difficult to determine the exact consequences of global warming.

In estimating the likely impacts of greenhouse warming, it is notonly necessary to project climatic conditions many years into thefuture. Adjustments by human and natural ecosystems must also betaken into account. Farmers adjust their behavior in response to changing weather patterns, as do plants and animals. A proper analysis of the impacts of greenhouse warming must also account for adjustments in national and regional economies as well as in other human and natural systems.

Because the United States is a large country with many intellectualand material resources and a wide range of climatic zones, it is better prepared to cope with the consequences of climate change than are less well-endowed countries. Nevertheless, the necessary adjustments are not without economic and social costs, and economically sound measures need to be adopted that can reduce possible adverse consequences.

The greatest sensitivities to greenhouse warming in the United States derive from the limited capacities of ecosystems to adapt to climate change. Depending on the rapidity of the climatic changes and the ability of ecosystem components to migrate or adapt to new conditions, significant ecosystem stresses could arise with as yet unknown consequences. Another threat stems from possible sea level rise and saltwater incursion into coastal areas. The less we are willing to accept the risk of such future conditions, the greater our motivation to reduce or offset emissions today and take other precautionary measures.

If the climate does change, other countries will face greater difficultiesthan will the United States, especially poor countries or those withfewer and marginal climate zones. For example, cereal production probably will decrease in some of the currently high-production areas and increase in other regions, which will alter patterns of agricultural trade (although total global food production probably can be maintained at essentially the same level as would have occurred without climate change). Recognition that poor countries may both bear a greater burden and have less resources to cope was a major factor in the negotiations leading to the climate change convention.

Projections suggest that greenhouse gas emissions in developing countrieswill exceed those from the industrialized countries sometime earlyin the next century. Most of the increases in greenhouse gas emissions have been a product of the efforts of people to secure improved standards of food, clothing, shelter, comfort, and recreation. Rapidly growing populations and the pressure to develop their economies have led developing countries to substantially increase their emissions of greenhouse gases, just as emissions from the industrialized countries have continued to rise.

Although there clearly is a relationship between population, economicactivity, and climate change, it is not a simple one. Increasing population is one of the major factors affecting trends in greenhouse gas emissions. More people create greater demand for food, energy, clothing, and shelter. Producing such products emits greenhouse gases. Economic growth also produces more greenhouse gases. Many nations have policies to reduce population growth rates, but all nations seek to achieve rapid growth in per capita income. The reduction of greenhouse gas emissions is well served by the first objective but, depending on the means used, can be in conflict with the second.

Major greenhouse gases emitted by human activities include carbon dioxide, methane, chlorofluorocarbons (CFCs), hydrogenated chlorofluorocarbons (HCFCs), ozone, and nitrous oxide. Figure 1 shows different ways to reduce or offset these emissions ranked in order of their cost-effectiveness. The most cost-effective option (residential and commercial energy efficiency), if fully implemented, could reduce emissions by about 11 percent at a net savings of about $62 per ton. The second most cost-effective option (vehicle efficiency with no change in fleet attributes) could produce an additional 4 percent reduction in emissions at a net savings of about $40 per ton.

Overall, the United States could reduce its greenhouse gas emissionsby between 10 and 40 percent of the 1990 level (depending on theextent of implementation of each option) at very low cost. Some reductions may even be at a net savings if the proper policies are implemented. Implementation of the most cost-effective options would place the United States in a position of world leadership in the response to the threat of greenhouse warming.

Three general areas with the greatest promise of reducing or offsetting current emissions are: changing energy policy, eliminating halocarbon emissions, and using forest offsets.

The United States can reduce emissions of greenhouse gases by enhancingenergy conservation and efficiency.  Potential actions include:

• Adopt nationwide energy-efficient building codes

• Improve the efficiency of the U.S. automotive fleet through the use of an appropriate combination of regulation and tax incentives

• Strengthen federal and state support of mass transit

• Improve appliance efficiency standards

• Encourage public education and information programs for conservation and recycling

• Reform state public utility regulation to encourage electrical utilities to promote efficiency and conservation

• Sharply increase the emphasis on efficiency and conservation in the federal energy research and development budget

• Use federal and state purchases of goods and services to demonstrate ''best practice'' technologies and energy conservation programs

The efficiency of practically every end use of energy can be improved relatively inexpensively. Major reductions could be achieved in energy use in existing buildings through improvements in lighting, water heating, refrigeration, space heating and cooling, and cooking. Gains could be achieved in transportation by improving vehicle efficiency without downsizing or altering convenience. Significant gains could be achieved in industrial electricity use through fuel switching and improvements in process technologies.

Initial calculations show that some options could be implemented at a net savings. There are informational barriers to overcome, however. For example, homeowners may not be aware of the gains to be realized from high-efficiency furnaces. There are also institutional barriers. For example, most public utility commissions disallow a rate of return to power companies on efficiency and conservation options. The panel concluded that energy efficiency and conservation is a rich field for reducing greenhouse gas emissions.

The United States can make greenhouse warming a key factor in planningfor our future energy supply mix. A systems approach should be adoptedthat considers the interactions among supply, conversion, end use,and external effects in improving the economics and performance ofthe overall energy system. Action items include efforts to:

• Develop combined cycle systems that have efficiencies approaching 60 percent for both coal-and natural-gas-fired plants

• Encourage broader use of natural gas by identifying and removing obstacles in the distribution system

• Develop and test operationally a new generation of nuclear reactor technology that is designed to deal with safety, waste management, and public acceptability

• Increase research and development on alternative energy supply technologies (e.g., solar), and design energy systems using them in conjunction with other energy supply technologies to optimize economy and performance

• Accelerate efforts to assess the economic and technical feasibility of carbon dioxide sequestration from fossil-fuel-based generating plants

The future energy supply mix will change as new energy technologies and greenhouse warming take on increased importance. A systems approach should be used to optimize the economics and performance of future energy systems. Interactions among supply options, conversion systems, end use, and external effects should receive much more attention than they have in the past. Actions for improving energy supply systems must cover all important elements in the mix. Also, it is important to prepare for the possibility that greenhouse warming may become far more serious in the future.

Alternative energy technologies are unable currently or in the near future to replace fossil fuels as the major electricity source for this country. If fossil fuels had to be replaced now as the primary source of electricity, nuclear power appears to be the most technically feasible alternative. But nuclear reactor designs capable of meeting fail-safe criteria and satisfying public

concerns have not yet been demonstrated. A new generation of reactor design is needed that adequately addresses the full range of safety, waste management, economic, and other issues confronting nuclear power. Focused research and development work on a variety of alternative energy supply sources could result in large changes in future energy supplies.

U.S. institutions need to explore modes of social cost pricing ofenergy, with a goal of gradually introducing such a system.

On the basis of the principle that the polluter should pay, pricing of energy production and use should in an ideal world reflect the costs of the associated environmental problems. The concept of social cost pricing is a goal toward which to strive, but much research remains to be conducted on how to achieve or approximate this goal. Including all social, environmental, and other costs in energy prices would provide consumers and producers with the appropriate information to decide about fuel mix, new investments, and research and development. Phasing such a policy in over time is essential to avoid shocks caused by rapid price changes. It would best be coordinated internationally.

The United States should continue the aggressive phaseout of CFCand other halocarbon emissions and the development of substitutesthat minimize or eliminate greenhouse gas emissions.

Although estimates of the contribution of halocarbon emissions to greenhouse warming recently have been reduced, these substitutes continue to contribute to the depletion of stratospheric ozone. The 1987 Montreal Protocol, and the subsequent agreements reached in London and Berlin, set goals regarding the international phaseout of CFC manufacture and emissions. These agreements should be forcefully implemented.

Global deforestation needs to be reduced. The United States and other countries should:

• Participate in international programs to assess the extent of deforestation, especially in tropical regions, and to develop effective action plans to slow or halt deforestation.

• Undertake country-by-country programs of technical assistance or other incentives.

• Review domestic policies to remove subsidies and other incentives contributing to deforestation.

In addition to reducing the uptake of carbon dioxide in plants and soils and being a source of atmospheric carbon dioxide, deforestation contributes to other important problems: loss of species and reduction in the diversity of biologic systems, soil erosion, decreased capacity to retain water in soil and altered runoff of rainfall, and alteration of local weather patterns. The United States now has increasing forest cover, but tropical forests worldwide are being lost at a rapid rate. Nearly every aspect of tropical deforestation, however, is difficult to measure.

Even the amount of land deforested each year is subject to disagreement. Nevertheless, action should be initiated now to slow and eventually halt tropical deforestation. Such programs need to be developed by those countries where the affected forests are located in cooperation with other countries and international organizations. Developing countries with extensive tropical forests will require substantial technological and developmental aid if this goal is to be reached.

The United States should explore a moderate domestic reforestationprogram and support international reforestation efforts.

Reforestation offers the potential of offsetting a large amount of carbon dioxide emissions, but at a cost that increases sharply as the amount of offset increases. These costs include not only those of implementation, but also the loss of other productive uses of the land planted to forests, such as land for food production. Reforesting can, at best, only remove carbon dioxide from the atmosphere and store it during the lifetime of the trees. When a forest matures, the net uptake of carbon dioxide stops. If the reforested areas are then harvested, the only true offset of carbon dioxide buildup is the amount of carbon stored as lumber or other long-lived products. However, the wood might be used as a sustained-yield energy crop to replace fossil fuel use. The acreage available within the United States for reforestation, and the amount of carbon dioxide that could be captured on these lands with appropriate kinds of trees, are controversial and may be limited. Many details remain to be resolved.

Human societies and natural systems of plants and animals change over time and react to changing climate just as they react to other forces. It would be fruitless to try to maintain all human and natural communities in their current forms. There are actions that can be taken now, however, to help people and natural systems adjust to some of the anticipated impacts of greenhouse warming by increasing resilience to climate change. Moreover, as noted previously, the Academy panel concluded that in all likelihood the United States can probably adapt and adjust without great difficulty.

An effective way to reduce vulnerability to future climate change is to make affected human systems more robust to current variationsin climate. Specific actions include:

• Maintain basic, applied, and experimental agricultural research to help farmers and commerce adapt to climate change and thus ensure ample food.

• Make water supply more robust by coping with present variability. Efficiency of use should be increased by greater reliance on water markets and by better management of present systems of supply.

• Plan margins of safety for long-lived structures to take into consideration possible climate change.

Any future climate change is likely to increase the current rate of loss of biodiversity while at the same time increasing the value of genetic resources. Greenhouse warming therefore adds urgency toprograms to preserve our biological heritage. Even without greenhouse warming, steps are warranted to slow present losses in biodiversity. Specific actions that should be taken include:

• Establish and manage areas encompassing full ranges of habitats

• Inventory little-known organisms and sites

• Collect key organisms in repositories such as seed banks

• Search for new active compounds in wild plants and animals

• Control and manage wild species to avoid over-exploitation

• Pursue captive breeding and propagation of valuable species that have had their habitats usurped or populations drastically reduced

• Review policies, laws, and administrative procedures that have the effect of promoting species destruction

• Consider purchasing land or easements suitable for helping vulnerable species to migrate to new habitats

Data collection and research can contribute to reducing the uncertaintiesof greenhouse warming. The return on investment in research is likely to be great. Actions should be taken in the following areas:

• Continue and expand the collection and dissemination of data that provide an uninterrupted record of the evolving climate and of data that are (or will become) needed for the improvement and testing of climate models.

• Improve weather forecasts, especially of extremes, for weeks and seasons to ease adaptation to climate change.

• Continue to identify those mechanisms that play a significant role in the climatic response to changing concentrations of greenhouse gases. Develop and/or improve quantification of all such mechanisms at a scale appropriate for climate models.

• Conduct field research on entire systems of species over many years to learn how carbon dioxide enrichment alters the mix of species and changes the total production or quality of biomass. Research should be accelerated to determine how greenhouse warming might affect biodiversity.

• Strengthen research on social and economic aspects of global change and greenhouse warming.

• Undertake research and development projects to improve our understanding of both the potential of large-scale "geoengineering" options for reducing or offsetting global

warming and their possible side-effects. This is not a recommendation that geoengineering options be undertaken at this time, but rather that we learn more about their likely advantages and disadvantages.

As the largest source of current greenhouse gas emissions, the United States should exercise leadership in addressing responses to greenhouse warming.

The United States should participate fully with officials at an appropriatelevel in international agreements and in programs to address greenhousewarming, including diplomatic conventions and research and developmentefforts.

The United States should participate fully in mechanisms for implementing the climate change convention and continue its active scientific role in related topics. The global character of greenhouse warming provides a special opportunity in the area of research and development. International cooperation in research and development should be encouraged through governmental and private sector agreements. International organizations providing funds for development should be encouraged to evaluate projects meeting demand for energy growth by conservation methods on an equal footing with projects entailing construction of new production capacity.

In addition, control of population growth has the potential to makea major contribution to raising living standards and to easing environmentalproblems like greenhouse warming. The United States should resumefull participation in international programs to slow population growthand should contribute its share to their financial and other support.²

Population size and economic activity both affect greenhouse gas emissions. Even with rapid technological advance, slowing global population growth is a necessary component of a long-term effort to control worldwide emissions of greenhouse gases. Reducing population growth alone, however, may not reduce emissions of greenhouse gases because it may also stimulate growth in per capita income. If the nature of economic activity (especially energy use) changes, some growth will be possible with far less greenhouse gas emissions.

Encouraging voluntary population control programs is of considerable benefit for slowing future emissions of greenhouse gases. In addition, countries vulnerable to the possible impacts of climate change would be better able to adapt to those changes if their populations were smaller and they had higher per capita income.

Even given the considerable uncertainties in our knowledge, greenhousewarming poses a potential threat sufficient to merit prompt responses. People in this country could probably adapt to the likely changes associated with greenhouse warming. The costs, however, could be substantial. Investment in mitigation measures acts as insuranceprotection against the great uncertainties and the possibility ofdramatic surprises. In addition, substantial mitigation can be accomplished at modest cost. In other words, insurance is cheap. Such insurancewill be effective, however, only to the extent that mitigation optionsare implemented effectively.

Implementation of the recommendations outlined here would establish the United States as a world leader in addressing environmental problems and would help fulfill the provisions of the climate change convention.