Rise in Global Mean Sea Level (Very Probable)

A further rise of 4-12 inches in mean sea level by the year 2050 is estimated

due to thermal expansion of warmer sea water. Continued sea level rise is expected for many centuries, probably to much higher values.

Summer Mid-Continental Dryness and Warming (Probable)

Model studies predict a marked decrease of soil moisture and elevated temperatures over summer mid-latitude continents. This result is sensitive to model assumptions about land-surface processes and projected levels of sulfate aerosol pollution.

Reduction of Ocean Overturning (Probable)

The predicted increase in precipitation in high northern latitudes would reduce the salinity, and hence the density in the oceans there. This effect slows down the tendency for water to sink, thus suppressing the overturning circulation.

Modeling of Cloud-Radiation Feedbacks (uncertain)

Some progress is being made in modeling the cloud-radiation response to increasing greenhouse gases. However, understanding the cloud response is still the most serious barrier to more confident predictions about climate warming.

Increased Tropical Storm Intensities (uncertain)

Some calculations suggest that a warmer, wetter atmosphere could lead to increased intensities of tropical storms, such as hurricanes. Presently, this has not been properly addressed due to inadequate computer power and to uncertainties in regional climate change predictions.

Regional and Temporal Details of the Next 25 Years (uncertain)

I have described calculated changes averaged over decades in the middle of the next century. The predicted warming up to now is not yet large compared to natural climate fluctuations. Such natural fluctuations will continue to occur. On these shorter time scales, the natural fluctuations can artificially reduce or enhance apparent measured greenhouse warming signals.

Even though these uncertainties are daunting, important advances have already been achieved in observing, understanding, and modeling the climate. Today's models can simulate many aspects of climate and its changes. Indeed, it was these advances that led to today's increased awareness of climate change and its implications. This awareness has, in turn, escalated the need for more reliable climate predictions.

CONGR

Although major progress has been made, much more needs to be learned.

More focussed efforts are needed world-wide to provide a long-term climate measuring system. This must be backed by a commitment to continue such measurements over many decades.

Focussed research into climate processes must be continued. Theories must

be formulated and re-evaluated in the light of newer data. To reduce uncertainty, climate modeling efforts must receive resources that are in balance with the broader scientific programs.

The U.S. Global Change Research Program is making excellent progress on these fronts. However, sustained efforts will be required in the years ahead. This is particularly true for measuring climate change. This needs a long-term commitment that is not yet evident. Without a better climate-change measuring system, neither our research nor our predictions can be properly evaluated.

Personally, I believe that the state of knowledge of the wide range of possible impacts and costs of climate change is far less certain than are the predictions for the climate system. An investment for research in this climate impact arena will pay large dividends and greatly aid policy planning.

Through long-term research and measurements, uncertainties will decrease and confidence for predicting climate changes will increase. However, surprises inevitably will hit us that may either decrease or increase the predicted effects. I predict with high confidence that society's demand for detailed climate change predictions will continue to increase faster than we can provide them.

In summary, the greenhouse warming effect is quite real. The state of the science is strong, but important uncertainties remain. Finally, it is a "virtually certain" bet that this problem will refuse to go away, no matter what is said or done about it over the next five years.

Thank you.

Mr. ROHRABACHER. Thank you very much, doctor.

Dr. Michaels?

STATEMENT OF DR. PATRICK J. MICHAELS, ASSOCIATE PROFESSOR, DEPARTMENT OF ENVIRONMENTAL SCIENCE, UNIVERSITY OF VIRGINIA

Dr. MICHAELS. Thank you, Mr. Chairman. I should say that I am an Associate Professor.

Mr. ROHRABACHER. Doctor, could you turn your microphone on and sort of lean into there.

Dr. MICHAELS. There we go.

Mr. ROHRABACHER. I want to make sure everybody can hear. Maybe pull it a little closer to you.

Dr. MICHAELS. I should say I am Associate Professor of Environmental Sciences, and at 4:00 o'clock today, I will be given my promotion seminar, so hopefully that will change in a very short period.

Controversy surrounding the issue of global warming is a classic example of what I think is the normal and creative scientific tension that exists between those who formulate models or hypotheses and those who evaluate such models with observed data.

Unfortunately, this issue has evolved in a highly politicized climate. For the last decade, a community of scientists, often referred to as a small minority, has argued that, based upon the data on climate change, the modeled warming was too large, and therefore any intrusive policy would not be based upon reliable models of global warming.

This view has been cast in a very negative political light, which has had a chilling effect on scientific free speech.

At the same time, testimony has repeatedly been given in front of this Congress that the modeled and observed temperatures were broadly consistent. This view has been amply rewarded. Nonetheless, these two views have never been reconciled scientifically.

The early suite of models produced an average warming of about 4 degrees celsius for doubling carbon dioxide, and the data suggested a much lower number, about 1 to 1.5 degrees of additional warming.

The most important development in the last two years is that it is now acknowledged that the community that argued for the lower numbers appears more likely to be correct. Moreover, it is apparent that the climate model that was most heavily cited by the United Nations in a special 1992 supplementary report on climate change, which was prepared specifically to provide technical backing for the framework convention on climate change, it is now known that that model was known to be making large errors in the forecast of current temperature at the time of the adoption of the framework convention.

And yet this never entered into the debate surrounding that issue.

These observations strongly suggest that the scientific review process that bases these international agreements has been highly flawed, or there may have simply been omissions in communicating to responsible individuals how large the errors in these calculations

were.