Testimony before Committee on Science - March 6, 1996
Statement of
Dr. Robert T. Watson
Associate Director for Environment
Office of Science and Technology Policy
Executive Office of the President
before the
Committee on Science
United States House of Representatives
March 6, 1996

Mr. Chairman and Members of the Committee:

I greatly appreciate being given the opportunity to discuss global climate change with you and your subcommittee. I am the Associate Director of the Environment Division in the White House Office of Science and Technology Policy. The Administration believes that this is an extremely important environmental issue of profound importance to this and future generations.

My testimony on the scientific knowledge of climate change is based on the latest findings of the Intergovernmental Panel on Climate Change (IPCC) Assessment, conducted under the auspices of World Meteorological Organization (WMO) and United Nations Environment Programme (UNEP). I will discuss the U.S. Global Change Research Program (USGCRP) within the context of this international scientific consensus.

The IPCC reports were prepared by over five hundred authors and reviewed by over one thousand scientists from universities, government laboratories, industry, and other private sector organizations from developed and developing countries. They were subjected to both an "expert" review and an in-depth governmental review. The three Summaries for Policymakers and the Synthesis report, were ultimately approved line-by-line by governments and technical experts.

Two other international assessments, the UNEP Global Biodiversity Assessment, and the UNEP-WMO Stratospheric Ozone Depletion Assessment also provide a sound scientific basis for elements of the USGCRP, given the inter-relationship between these different issues.

Scope and Importance of the Climate Change Issue

While climate change is inherently a global issue, it is critical that we understand how climate will change at the regional scale and what the potential consequences may be. To be specific, we need to know how climate will change in the United States, what the consequences will be in different regions, and whether there are cost-effective solutions to slow climate change or adapt to it. Therefore, the scope of a comprehensive climate change research program should evaluate:

Current Understanding of Climate Change

The large majority of scientific experts have concluded, based on empirical evidence and simulations, that human activities have already affected the Earth's climate and that further human-induced climate change is inevitable. While a number of key scientific uncertainties remain, for the first time, the scientific community through the IPCC has stated "there is a discernible human influence on global climate." In other words, the question is not whether climate will change in response to human activities, but rather where (regional patterns), when (the rate of change) and by how much (magnitude).

It is also clear that climate change will, in many regions, adversely affect human health, ecological systems, and socio-economic sectors, including agriculture, forestry, fisheries, water resources, and human settlements. The good news is, however, that significant reductions in greenhouse gas emissions are technically feasible due to an extensive array of technologies and policy measures in the energy supply and energy demand sectors at little net cost to the economy. Such measures can slow climate change, but will require concerted R&D and demonstration to have these technologies penetrate the marketplace domestically or worldwide.

The following section summarizes the main IPCC conclusions for each of the three questions.

1. How do human activities affect regional and global climate?

Our ability to predict changes in climate at the regional level remains low, however we do know that:

2. What are the potential consequences of climate change?

In some cases, such as species loss, the impacts of climate change are irreversible. Developing countries are more vulnerable than developed countries to climate change because of their socio-economic conditions.

3. Are there technically feasible and cost-effective options to mitigate or adapt to climate change?

Research Priorities Related to Climate Change

This section will highlight some of the highest priority areas of research for each of the three major areas/questions discussed above.

1. What is the impact of human activities on regional and global climate in the context of natural climate variability?

There are a number of major challenges facing the scientific community if we are to improve our ability to predict future changes in regional and global climate. We need to:

2. What are the potential consequences of climate change?

To gain an improved understanding of the potential consequences of climate change, in the context of other stresses, will require a significant improvement in our ability to predict climate change at the regional level (including the location, severity, and frequency of extreme events), an improved understanding of key processes (including ecological, social, and economic), and an improved understanding of other stress factors such as air and water pollution, the demand for natural resources, and unsustainable management practices. We need to:

3. Are there technically feasible and cost-effective options to mitigate or adapt to climate change?

Assessing the technical feasibility and cost-effectiveness of options to mitigate or adapt to climate change will require an evaluation of the technical potential of mitigation technologies, their cost-effectiveness, and the barriers to the diffusion of these technologies into the market place for each of the key sectors including: energy supply (including fossil, renewables, and nuclear); energy demand (including transportation, buildings, industry and utilities); and land-use practices (including carbon sequestration in vegetation and soils in rangelands, agriculture and forests). This will require emphasis on:

Scope of the U.S. Global Change Research Program and Related Programs

The U.S. Global Change Research Program (USGCRP), which has a broader scope than global climate change, is a critical tool in addressing the uncertainties discussed above. It is designed to address a number of highly inter-related global environmental issues, including global climate change, seasonal to inter-annual climate fluctuations, stratospheric ozone depletion, changes in tropospheric chemistry, and land-use/land-cover changes. In addition, the USGCRP is closely coordinated with other research programs that study related environmental issues such as biological diversity, resource use and management, air quality, water resources, and natural disasters. This coordination is achieved through the Committee on Environment and Natural Resources (CENR) of the National Science and Technology Council (NSTC).

Importance of the Federal Government Role in USGCRP

Significant progress in understanding global climate change (and the other global environmental issues as mentioned above) has been made over the past decade or so because of the strong bipartisan commitment to the USGCRP. This was a program initiated by President Reagan and further developed by President Bush and Clinton with strong support from Congress. All three Administrations and Congress recognized the social and economic importance of the global environmental issues encompassed by the USGCRP. There was general agreement that enhanced scientific understanding is essential for the development of appropriate, cost-effective options to mitigate or adapt to climate change, ensure environmental protection, protect the health of our citizens, and ensure that economic and national security are not jeopardized.

The Federal government, in conjunction with the private sector should, and must, continue its commitment to a better understanding of our global environment. While the private sector has some limited research capability in the area of climate change, only the Federal government, in strong collaboration with its colleagues in academia, can adequately address the breadth of this critically important social issue.

Effective international cooperation is needed as well. The USGCRP provided most of the critical scientific information needed to develop national and international policies for safeguarding the Earth's protective ozone layer. Only a well-funded, scientifically-based USGCRP can provide the enhanced scientific and technical information needed to guide effective policy formulation for coping with climate change.

Implication for the Current USGCRP

The USGCRP is a well designed scientific program that is providing high quality policy-relevant information. During the last decade or so the program has made a large number of significant scientific advances and demonstrated flexibility in responding to new scientific challenges. Let me provide just two examples of scientific progress and programmatic responsiveness -- there are dozens more:

The scope and balance of activities in the USGCRP will need to continue to evolve in the future just as they have in the past. This program must, and does, devote significant resources to space and in situ observations and data management in addition to process studies, modelling and analysis. To understand climate change, both natural and anthropogenic, USGCRP will have to place an increasing emphasis on understanding the consequences of climate change at the regional level and on some key socio-economic aspects, including the costs and benefits of reducing greenhouse gas emissions. To perform such an analysis will require, among others, improved techniques to value biological resources and biodiversity, both in terms of market and non-market value, and understanding barriers to the diffusion of technologies into the market place.

We need to maintain the high quality science-driven USGCRP that emerged during the Reagan and Bush Administrations and which has been strongly supported by the Clinton Administration. The need to observe, understand and predict the Earth system has been given even greater emphasis by the latest set of findings from the IPCC. In particular, we need to improve our ability to predict climate change at the regional level, and we need an increased emphasis on understanding the consequences of climate change. The latter will require more research into basic ecological processes, development of more sophisticated modeling frameworks, and the establishment of improved capabilities for ground- and space-based monitoring and data management. In addition, we need better databases for vulnerability assessment and planning of adaptation, including data on population trends, resource utilization, and the value of natural and economic resources. The development of a broad range of sectoral and integrated modeling capabilities is also required to determine the potential significance of global change for the United States and the world.


The scientists of the world have agreed that climate is changing and that there is a discernible human influence. However, policymakers are faced with responding to the risks posed by anthropogenic emissions of greenhouse gases in the face of scientific uncertainties about the details -- the magnitude, regional impacts, and rate of climate change. Climate-induced environmental changes cannot be reversed quickly, if at all, due to the long time scales associated with the climate system. Ultimately, it is not for scientists but rather for decisonmakers to decide what "dangerous" means under the Framework Convention on Climate Change.

Decisions taken during the next few years may limit the range of possible policy options in the future because high near-term emissions would require deeper reductions in the future to meet any given target concentration. Delaying action might reduce the overall costs of mitigation if potential technological advances are vigorously pursued in the interim, but could increase both the rate and the eventual magnitude of climate change, and hence the adaptation and damage costs.

Policymakers will have to decide on the degree to which they want to take precautionary measures by mitigating greenhouse gas emissions and enhancing the resilience of vulnerable systems by means of adaptation. Uncertainty does not mean that a nation or the world community cannot position itself better to cope with the broad range of possible climate changes or protect against potentially costly future outcomes. Delaying such measures may leave a nation or the world poorly prepared to deal with adverse changes and may increase the possibility of irreversible or very costly consequences. Options for adapting to change or mitigating change that can be justified for other reasons today (e.g., abatement of air and water pollution) and make society more flexible or resilient to anticipated adverse effects of climate change appear particularly desirable.

Finally, it is precisely the fact that aspects of global climate change remain uncertain that argues most strongly for a comprehensive research effort. Dealing with the issue of climate change requires a greater understanding of the Earth system. The complexity of the Earth system, a complexity agreed on by all those who have testified today, makes this an immense scientific challenge. I think nearly all the panelists would also agree that strong Federal science programs and Federally funded University research are critical to meet this challenge. The sheer magnitude of this task, combined with the seriousness of the potential consequences of climate change, provide a clear justification for the maintenance of a strong national research program focused on this issue.

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