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