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: