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PREPARED STATEMENT OF JERRY F. COSTELLO

Energy plays a critical role in our economy. As a result, I believe it is in the nation's best interest to make improvements in energy efficiency, to diversify our use of energy resources, and to expand energy supplies. The coal industry is of great importance to my district in Southwestern Illinois which, as you may know, is rich in high-sulfur coal. The shifting of production to low-sulfur coal has cost many of my constituents high-paying jobs. I support research and development of cleaner fossil fuel initiatives which includes a program to develop new technologies for cleaner, higher efficiency coal combustion with the hopes of achieving a healthier environment.

I am also looking forward to hearing more about non-fossil energy sources including ethanol, solar power, and wind energy. I welcome our panel of witnesses and look forward to their testimony.

APPENDIX 3: Written Statements, Biographies, Answers to Post-Hearing Questions, and Financial Disclosures

PREPARED STATEMENT OF DANIEL L. ALBRITTON

Good morning my name is Dan Albritton. I am Director of the Aeronomy Laboratory of NOAA Research. Thank you for the invitation to report the findings of the recent report of the Intergovernmental Panel on Climate Change (IPCC). The IPCC was set up jointly by the World Meteorological Organization and the United Nations Environment Programme to provide an authoritative international statement of scientific opinion on climate change.

The Laboratory that I direct is located in Boulder, Colorado, and studies the global chemistry and dynamics of the Earth's atmosphere. Scientists in our Laboratory have played major roles in understanding the stratospheric ozone layer, greenhouse gases, and regional air quality.

I have also been involved in providing scientific information to policymakers in government and industry, including both those in the U.S. and internationally, on the ozone layer and the greenhouse effect. Most recently, I served as one of the Coordinating Lead Authors of the state-of-understanding assessment of the IPCC: “Climate Change 2001. The Scientific Basis".

I appreciate the invitation to appear before your Committee and to summarize the current state of scientific understanding of the climate system. My information is based on the set of findings of the recent IPCC report, which has been three years in preparation and which was completed last month. This assessment represents the work of over a hundred scientific authors worldwide. It is based on scientific literature, and was reviewed by hundreds of scientific peers. It is the understanding of these authors that I am pleased to summarize here today.

Before addressing the new findings of the recent IPCC report, let me note two points that have been long-known, very well-understood, and deeply underscored in all past IPCC reports and other such scientific summaries:

• The "greenhouse effect” is real, and it is a natural part of our planet. A small percentage (~2%) of the atmosphere is, and long has been, composed of greenhouse gases, which are constituents such as water vapor, carbon dioxide, and methane that effectively prevent part of the heat radiated by the Earth's surface from otherwise escaping to space. The global system responds to this trapped heat with a climate that is warmer, on the average, than it would be otherwise without the presence of these gases.

Why then, if the greenhouse effect is a natural part of the planet, is it referred to as "an issue"? The reason is that it has been very clear for some time that we are changing the greenhouse radiation balance, namely:

• Greenhouse gases are increasing in the atmosphere because of human activities, and increasingly trapping more heat. Direct atmospheric measurements made over the past 40-plus years have documented impeccably the steady growth in the atmospheric abundance of carbon dioxide. In addition to these direct real-time measurements, ice cores have revealed the atmospheric carbon dioxide concentrations of the distant past. That is, measurements using the air from bubbles that were trapped within the layers of accumulating snow show that atmospheric carbon dioxide has increased by about 30% over the Industrial Era (since 1750), compared to the relatively constant abundance that it had over the preceding 750 years of the past millennium. The predominant cause of this increase in carbon dioxide is the combustion of fossil fuels and the burning of forests. Moreover, methane abundance has doubled over the Industrial Era. Similarly, other heat-trapping gases are also increasing as a result of human activities.

But, what do these changes in greenhouse gas abundances imply for changes in the climate system? Indeed, what climate changes have been observed, both recently and earlier? How well are the causes of those changes understood? Namely, what are natural changes and what are changes due to greenhouse-gas increases? And, what does this understanding potentially imply about the climate of the future?

These questions relate to the scientific points that you asked me to address today. In doing so, I will summarize three major conclusions from the recent IPCC climatescience report. These conclusions are based, in order, on measurements, analyses, and projections, which are, of course, understandably in an order of decreasing scientific confidence.

• There is a growing set of observations that yield a collective picture of a warming world over the past century. The global surface temperature very likely has increased over the 20th century by 0.7 to 1.4 degrees Fahrenheit. The average temperature increase in the Northern Hemisphere over the 20th century is likely to have been the largest of any century during the past 1,000

years, based on "proxy” data (and their uncertainties) from tree rings, corals, ice cores, and historical records. (See Figure 1, IPCC Working Group I Summary for Policymakers, 2001) Other observed changes are consistent with this warming. There has been a widespread retreat of mountain glaciers in nonpolar regions. Snow cover and ice extent have decreased. The global-average sea level has risen between 4 and 8 inches, which is consistent with a warmer ocean occupying more space because of the thermal expansion of water.

• There is new and stronger evidence that most of the warming observed over the last 50 years is attributed to human activities. The 1995 IPCC climatescience assessment report concluded: "The balance of evidence suggests a discernible human influence on global climate." Although many of the sources of uncertainty identified in 1995 still remain to some degree, new evidence and improved understanding support the above updated conclusion. Namely, recent analyses have compared the surface temperatures measured over the last 140 years to those simulated by mathematical models of the climate system, thereby evaluating the degree to which human influences can be detected. Both natural climate-change agents (solar variation and episodic explosive volcanic eruptions) and human-related agents (greenhouse gases and sulfur-containing fine particles) were included. The natural climate-change agents alone do not explain the warming in the second half of the 20th century. The best agreement between observations and model simulations over the last 140 years is found when both human-related and natural climatechange agents are included in the simulations. (Compare Figures (4a) and (4c), IPCC WG I SPM, 2001) In light of such new evidence and taking into account the remaining uncertainties, the IPCC scientists concluded that most of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse gas concentrations.

• Based on scenarios of future human activities, global average temperature and sea level are projected to rise over this century. Clearly, the atmospheric abundances of greenhouse gases over the next 100 years cannot be predicted with high confidence, since, the future emissions of these gases will depend on many diverse factors, e.g., world population, economies, technologies, and human choices, which are not uniquely specifiable. Rather, the IPCC assessment endeavor aimed at establishing a set of scenarios of greenhouse gas abundances, with each based on a picture of what the world plausibly could be over the 21st century. Based on these scenarios and the estimated uncertainties in climate models, the resulting projection for the global average temperature in the year 2100 ranges from 2.5 to 10 degrees Fahrenheit (See Figure 5, IPCC WĠ I SPM, 2001). Such a projected rate of warming would be much larger than the observed 20th-century changes and would very likely be without precedent during at least the last 10,000 years. The corresponding projected increase in global sea level by the end of this century ranges from 3.5 to 35 inches. Uncertainties in the understanding of some climate processes make it more difficult to project meaningfully the corresponding changes in regional climate. However, it is very likely that nearly all land areas will warm more rapidly than the global_average, particularly those at northern high latitudes in the cold season. Further, it is very likely that many features of the weather will become more variable, e.g., higher maximum temperatures over nearly all land areas and more intense precipitation events over many areas.

The last point that I would like to make is not a "new finding". Indeed, it has been underscored with very high confidence in all of the IPCC climate-science assessment reports (1990, 1995, and 2001). I repeat it here because it is a key (perhaps "the" key) aspect of a greenhouse-gas-induced climate change:

• A greenhouse-gas warming could be reversed only very slowly. This quasiirreversibility arises because of the slow rate of removal (centuries) from the atmosphere of many of the greenhouse gases and because of the large resistance of the oceans to thermal changes. For example, several centuries after carbon dioxide emissions occur, about a quarter of the increase in the atmospheric concentrations caused by these emissions is projected to still be in the atmosphere. Additionally, global average temperature increases and rising sea level 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 timescales (centuries) on which the deep ocean adjusts to climate change.

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