From: baalke@zagami.jpl.nasa.gov   
      
   Elvia Thompson   
   Headquarters, Washington                  December 10, 2003   
   (Phone: 202/358-1696)   
      
   Rob Gutro   
   Goddard Space Flight Center, Greenbelt, Md.   
   (Phone: 301/286-4044; at AGU: 415/905-1007)   
      
   NOTE TO EDITORS: N03-138   
      
   SCIENTISTS "RECONSTRUCT" EARTH'S CLIMATE OVER PAST MILLENNIA   
      
        Using the perspective of the last few centuries and   
   millennia, speakers in a press conference at the Fall Meeting   
   of the American Geophysical Union in San Francisco will   
   discuss the latest research involving climate reconstructions   
   and different climate models.   
      
   The press conference features Caspar Ammann of the National   
   Center for Atmospheric Research (NCAR), Boulder, Colo.; Drew   
   Shindell of NASA's Goddard Institute for Space Studies, New   
   York; and Tom Crowley of Duke University, Durham, N.C. The   
   press conference is at 5 p.m. EST, Thursday, December 11 in   
   the Moscone Convention Center West, Room 2012.   
      
   Changes in the sun's activity have been considered responsible   
   for some part of past climatic variations. Although useful   
   measurements of solar energy are limited to the last 25 years   
   of satellite data, this record is not long enough to confirm   
   potential trends in solar energy changes over time. Tentative   
   connections between the measured solar activity, with sunspots   
   or the production of specific particles in the Earth's   
   atmosphere (such as carbon-14 and beryllium-10), have been   
   used to estimate past solar energy.   
      
   Ammann will discuss how he used a set of irradiance estimates   
   with the NCAR coupled Ocean-Atmosphere General Circulation   
   computer model to show the climate system contains a clearly   
   detectable signal from the sun. Ammann's work with the model   
   also demonstrates that smaller, rather than larger, background   
   trends in the sun's emitted energy are in better agreement   
   with the long-term climate record, as obtained from proxy   
   climate records, such as tree-ring data.   
      
   Shindell will discuss how he used a climate model that   
   included solar radiation changes, volcanic eruptions, and   
   natural internal variability to arrive at a more accurate look   
   at Earth's changing climate today. Shindell said that while   
   solar radiation changes and volcanoes exert a similar   
   influence on global or hemispheric average-temperature   
   changes, the solar component has the biggest regional effect   
   over time scales of decades to centuries, while volcanoes   
   cause the largest year-to-year changes.   
      
   Crowley will discuss one of the goals of climate modeling, to   
   test whether moderately reliable predictions of regional   
   climate change can be made under global warming scenarios.   
   Using paleoclimate data, scientists can in some cases test   
   computer climate-model performance. This testing would occur   
   for a time period in which models accurately predict the   
   larger (hemispheric-scale) response to changes in the Earth's   
   radiation balance.   
      
   NASA's Earth Science Enterprise is dedicated to understanding   
   the Earth as an integrated system and applying Earth System   
   Science to improve prediction of climate, weather and natural   
   hazards using the unique vantage point of space.   
      
   NCAR is a research laboratory operated by the University   
   Corporation for Atmospheric Research, a consortium of 67   
   universities offering doctoral programs in the atmospheric and   
   related sciences. NCAR's primary sponsor is the National   
   Science Foundation.   
      
   For more information and images related to the press   
   conference on the Internet, visit:   
      
   http://www.gsfc.nasa.gov/topstory/2003/1211millenium.html   
      
      
   -end-   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)