Press Release: New Study Shows Higher Rate of Warming and Sea Level Rise Than Previously Expected

For Immediate Release:
June 29, 1999

Contact: Kelly Sullivan/Heather Fass

New Study Shows Higher Rate of Warming and Sea Level Rise Than Previously Expected: U.S. Temperature Rise Expected to be Greater Than Global Average

WASHINGTON, D.C. — A new report released by the Pew Center on Global Climate Change reveals slightly higher rates of warming and sea level rise than predicted in 1995 by an international group of scientists on the Intergovernmental Panel on Climate Change (IPCC). The new estimates are based on preliminary versions of four new emissions scenarios identified by the IPCC Special Report on Emissions Scenarios (SRES).

The projected changes are 1.3 - 4.0°C (2.3 - 7.2°F) for global-mean temperature (previous IPCC projections were 0.8 - 3.5°C; 1.4 - 6.3°F), and 17 to 99 cm. (7 to 39 in.) for sea level rise by 2100 (versus 13 to 94 cm.; 5 to 37 in. from the IPCC). These high projected increases in temperature and sea level rise are due to lower levels of sulfur dioxide emissions than previous projections (efforts to reduce sulfur dioxide - another pollutant - could result in increased warming since sulfate particles cool the atmosphere).

For temperature, these values mean that future changes in global-mean temperatures will be 2 to 7 times more rapid than those of the 20th century and that rises in sea level will occur at rates 1 to 7 times those of the 20th century.

"As policymakers, industry and the public tackle the challenges of climate change, understanding the seriousness and complexity of the issue is critical to crafting the most effective responses," said Eileen Claussen, Executive Director, Pew Center on Global Climate Change. "The data and likely impacts outlined in this study should encourage concrete steps to reduce greenhouse gas emissions."

The study, "The Science of Climate Change: Global and U.S. Perspectives," was conducted and written by Tom M.L. Wigley of the National Center for Atmospheric Research for the Pew Center on Global Climate Change.

Based on results from a number of climate models, the rate of future warming for the United States is expected to be noticeably faster than the global-mean rate. While the Southeast and Southwest tend to show warming slightly below the global-mean, the northernmost states from North Dakota eastward to Maine show enhanced warming by a factor of up to two during the winter months. Future regional-scale precipitation changes are highly uncertain. The only result that is common to all climate models is an increase in winter precipitation in northern latitudes, from the northern Great Plains to the northeastern states.

The study also found that changes in climate extremes were likely.

  • Warm temperature extremes will almost certainly become more frequent;
  • Cold temperature extremes will almost certainly become less frequent;
  • The frequency of high precipitation events is likely to increase;
  • It is likely that rainfall amounts associated with hurricanes will increase; and
  • An increase in the frequency and intensity of hurricanes in the North Atlantic region is possible.

F or all extreme events, however, it is unlikely that the projected changes will become evident in a statistically convincing way for many decades, with the exception of temperature extremes, which should become evident sooner.

This most recent research also strengthens the IPCC statement that "the balance of evidence suggests a discernible human influence on global climate." First, climate model estimates of global-mean temperature changes over the 20th Century, and of the patterns of temperature change, are consistent with observations. Second, the effects of solar changes on the climate have been better quantified. They show that the sun can only account for about one-third of the observed global-mean warming. Third, scientists are beginning to understand why recent trends in the temperature of the lower to mid-troposphere derived from satellite data differ from those at the surface.

"This research provides valuable information that should move the climate change debate beyond questions about the science and towards realistic solutions," said Claussen.

The findings in the study will be highlighted in a print advertisement supported by the Pew Center, which is scheduled to appear in The New York Times, The Washington Post, National Journal, Roll Call and Newsweek.

The Pew Center was established in May 1998 by the Pew Charitable Trusts, one of the nation's largest philanthropies and an influential voice in efforts to improve the quality of America's environment. The Pew Center is conducting studies, launching public education efforts, promoting climate change solutions globally and working with businesses to develop marketplace solutions to reduce greenhouse gases. The Pew Center is led by Eileen Claussen the former U.S. Assistant Secretary of State for Oceans and International Environmental and Scientific Affairs.

The Pew Center includes the Business Environmental Leadership Council, which is composed of 21 major, largely Fortune 500 corporations all working with the Pew Center to address issues related to climate change. The companies do not contribute financially to the Pew Center - it is solely supported by contributions from charitable foundations.