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concentrations caused by these emissions is projected to still be in the atmosphere. Additionally, global average temperature increases and rising sea levels are projected to continue for hundreds of years after a stabilization of greenhouse gas concentrations (including a stabilization at today's abundances), owing to the long time scales (decades to centuries) on which the deep ocean adjusts to climate change. Because of its large specific heat capacity and mass, the world ocean can store large amounts of heat and remove this heat from direct contact with the atmosphere for long periods of time.
*It is presently not possible to generally define a safe level of greenhouse gases. This issue was specifically addressed in the recent NAS study. There are several difficulties related to answering this question. First, as I have indicated, there are still large uncertainties related to the projected rate and magnitude of climate change. The determination of an acceptable concentration of greenhouse gases depends on knowing this as well as knowledge of the risks and vulnerabilities to climate change. A range of climate sensitivities and emission scenarios could be used to explore sensitivities to climate change. A first attempt was reported in the National Climate Assessment and the recent PCC report. Analyses reveal that sectors and regions vary in their sensitivity to climate change, but generally those societies and systems least able to adapt and those regions with the largest changes are at greatest risk. This includes the poorer nations and sectors of our society, natural ecosystems, and those regions likely to see the largest changes. For example, on average, the largest increases of temperature and relative changes in precipitation projected by all models are in the mid to high latitudes of the Northern Hemisphere. Clearly, as the rate and magnitude of climate change increases, the risk of exceeding a safe level of greenhouse gases also increases. This includes the possibility of surprises. As greenhouse gases continue to increase there is an ever increasing, but still very small chance, that the climate system could respond in an unpredictable fashion. Examples include a shut-down of the transport of heat in the North Atlantic Ocean thermohaline circulation which could lead to large regional climate anomalies, melting of the Greenland Ice Sheet or the Antarctic Ice Shelf, substantial increases in hurricane intensity, and other possibilities. None of these changes are foreseen at present, but we cannot absolutely dismiss the possibility of a surprisingly large and rapid change in climate.
*Because there is considerable uncertainty in current understanding of how the natural variability of the climate system reacts to emissions of greenhouse gases and aerosols, current estimates of the magnitude and impacts of future warming are subject to future adjustments (either upward or downward). Nonetheless, it is noteworthy that our best estimates of climate sensitivity to greenhouse gases have essentially remained unchanged over the past three decades, since the first National Academy of Sciences report on this topic back in the 1960s. In addition to the uncertainty related to the rate and magnitude of climate change, there is considerable uncertainty related to quantifying the impact of climate change on natural and human systems.
*To address these uncertainties, several areas of study have been identified in the assessments. Because understanding the climate system and its impacts is so complex, progress will be hindered by the weakest link in the chain. At the present time, there are several weak links that need to be addressed. First and foremost a climate observing system is needed to monitor long
term change for basic variables needed to describe the climate system. Current observing systems yield uncertainties in several key parameters, especially on regional and local space scales. Although we have been able to link observed changes to human activities, it is not possible to quantitatively identify the specific contribution of each forcing factor, which is required for the most effective strategy to prevent large or rapid climate change.
To address these imcertainties, the President has directed the Cabinet-level review of U.S. climate change policy. Based on the Cabinet's initial findings, the President in his June 11 remarks committed his Administration to invest in climate science. He announced the establishment of the U.S. Climate Change Research Initiative to study areas of uncertainty and to identify areas where investments are critical. He directed the “Secretary of Commerce, working with other agencies, to set priorities for additional investments in climate change research, review such investments, and to provide coordination amongst federal agencies. We will fully fund high-priority areas for climate change science over the next five years. We'll also provide resources to build climate observation systems in developing countries and encourage other developed nations to match our American commitment."
I would like to underscore that we will use the descriptions of the uncertainties identified in the NAS report as the basis for development of U.S. research in climate. Cited areas of uncertainty include:
Feedbacks in the climate system that determine the magnitude and rate of temperature increases and related precipitation changes Future usage of fossil fuels Carbon sequestration on land and in the ocean Details of regional climate change Natural climate variability and the interaction of these modes with other climate forcings including greenhouse gases and the direct and indirect effects of aerosols
Finally, we have found that no matter how good our understanding of future climate change might be, we ultimately must understand how this will impact natural and human systems. To achieve this understanding will require (a) interdisciplinary research that couples physical, chemical, biological, and human systems, (b) improved capability to integrate scientific knowledge, including its uncertainty, into effective decision support systems, and (c) a better understanding of the impact of multiple stresses on both human and natural systems at the regional and sectoral level.
I look forward to continuing to work with you on these issues. Thank you again for the invitation to appear today. I hope that this summary has been useful. I would be happy to address any questions.
Committee on the Science of Climate Change. Climate Change Science: An Analysis of Some Key Questions. National Academy Press: Washington, D.C. 2001. 28 pp.
Summary for Policy Makers, Climate Change 2001: The Scientific Basis. Summary for Policymakers and Technical Summary of the Working Group I Report. Cambridge University Press, 98pp. Also available at http://www.ipcc.ch. The full report will be available later this
Parallel IPCC reports:
Climate Change 2001: Impacts, Adaptation and Vulnerability - Contribution of Working
Climate Change 2001: Mitigation - Contribution of Working Group III to the
IPCC, 2000: [PCC Special Report on Emissions Scenarios. Cambridge University Press. Statement by
United States Senate
July 18, 2001
Mr. Chairman and members of the committee, thank you for this opportunity to testify on S.1008, the Byrd-Stevens Climate Change Strategy and Technology Innovation Act of 2001. My name is Eileen Claussen, and I am the President of the Pew Center on Global Climate Change.
The Pew Center on Global Climate Change is a non-profit, non-partisan and independent organization dedicated to providing credible information, straight answers and innovative solutions in the effort to address global climate change. Thirty-six major companies in the Pew Center's Business Environmental Leadership Council (BELC), most included in the Fortune 500, work with the Center to educate the public on the risks, challenges and solutions to climate change. (See Attachment A for the list of companies.) The BELC companies do not contribute financially to the Center.
Mr. Chairman, I believe that enacting the Byrd-Stevens bill will be an important first step in developing a serious domestic climate change program -- a step that should be taken quickly. This bipartisan bill will align our energy policy with the long-term goal of stabilizing atmospheric greenhouse gas concentrations. It will respond to concerns, often raised by other nations, that the U.S. has no basis for domestic action. And it will continue investigation into the uncertainties of the science and economics of climate change.
Most important among the many provisions of the Byrd-Stevens bill is the one that requires the development, within one year, of a U.S. Climate Change Response Strategy. This strategy will have the long-term goal of stabilizing greenhouse gas concentrations. To meet this goal, the strategy will rely on emissions mitigation measures, technology innovation, climate adaptation research, and efforts to resolve the remaining scientific and economic uncertainty. Allow me to comment on these elements.
At the Pew Center, we believe enough is known about the science and environmental impacts of climate change for us to take action now. As we have learned from the Intergovernmental Panel on Climate Change (IPCC), confirmed recently by the National Academy of Sciences (NAS), the scientific consensus is very strong that greenhouse gases are accumulating in Earth's atmosphere as a result of human activities, causing surface air temperatures and subsurface ocean temperatures to rise. Humaninduced warming and associated sea level rises are expected to continue through the 21st century. We are also likely to see increases in rainfall rates in some areas and increased
susceptibility of semi-arid regions to drought. As a consequence, according to the IPCC and NAS reports and our own peer-reviewed reports there likely will be substantial impacts to human health, agriculture, ecosystems, and coastlines. The high probability of these outcomes indicates the need for action now.
Even as we act, however, we need to refine our understanding of the causes and impacts of climate change - especially as they affect particular regions of our country and the world. This is will be especially important in developing the measures needed to adapt to climate change. Regardless of how quickly we act to mitigate climate change, the best scientific evidence tells us that we have already "bought” a changed climate to which we and our children will need to adapt. Obviously, the more quickly we mitigate, the less we will have to adapt, but some amount of adaptation is apparently inevitable.
For example, on the whole, U.S. agriculture is likely to adapt to the increases in temperature, droughts, floods, and evaporation rates expected over the next century. In specific regions of the U.S., however, the impacts might be significant. The sooner we can identify those regions, the sooner we can prepare the people and economies of those regions to adapt. The Byrd-Stevens bill creates a sound basis for giving priority to and investigating these issues.
We also applaud efforts to further analyze the uncertainties regarding the economic impacts of climate change: Work done by the Pew Center suggests that no existing model accurately predicts the economic effects of any given measure to mitigate climate change. Therefore, none of the cost information so handily bandied about can currently be viewed as reliable. We are hard at work to fill in many of the gaps in the models, but efforts, particularly to take the economic assessment to regional levels, would be most welcome.
Second, the Byrd-Stevens bill will promote technology innovation. In May, Senator Byrd said from the Senate floor that to address global climate change, “[w]hat is required ... is the equivalent of an industrial revolution.” Ile was exactly right. To effectively address climate change, we need to lower carbon intensity, become more energy efficient, promote carbon sequestration, and find ways to limit emissions of nonCO2 gases. This will require fundamentally new technologies, as well as dramatic improvements in existing ones. New, less carbon-intensive ways of producing, distributing and using energy will be essential. The redesign of industrial processes, consumer products and agricultural technologies and practices will also be critical. These changes can be introduced over decades as we turn over our existing capital stocks and establish new infrastructure. But we must begin making investments, building institutions, and implementing policies now. The Byrd-Stevens bill will provide a solid foundation for needed revolution in technology.
I applaud the Senators' efforts to deal with the very real institutional and budgetary challenges that have plagued federal energy research and development and technology diffusion for many years. I endorse the proposal in S. 1008 to create a new research and technology organization with a clear mission to foster the best, most cost