Scientists Determine Biological and Ecosystem Changes in Polar RegionsLinked to Solar Variability Over Past 12,000 Years (Forwarded)

News & Public Affairs
Lawrence Livermore National Laboratory

Contact: Anne Stark
Phone: (925) 422-9799
E-mail:

FOR IMMEDIATE RELEASE: September 26, 2003

NR-03-09-09

Scientists Determine Biological and Ecosystem Changes in Polar Regions Linked to
Solar Variability Over Past 12,000 Years

LIVERMORE, Calif. -- A Lawrence Livermore National Laboratory scientist, in
collaboration with an international team of colleagues, has reported that
noticeable changes in the sub-polar climate and ecosystems appear to be linked
to variations in the sun's intensity during the past 12,000 years.

The research, titled "Cyclic Variation and Solar Forcing of Holocene Climate in
the Alaskan Subarctic," is reported in today's (Sept. 26) issue of Science.

Using core sediment samples from Arolik Lake in the tundra region along the
southwestern coast of Alaska, Thomas Brown of Livermore's Center for Accelerator
Mass Spectrometry measured the amount of carbon-14 in samples to provide a
chronological framework for the biological and organic evidence of climate and
ecosystem changes, which occurred during the Holocene Epoch (12,000 years ago to
present).

By studying biological, geochemical and isotopic constituents of sediment
samples (such as biogenic silica from single-celled algae, which reflects lake
productivity), the researchers determined that variations of these components
provided evidence of climate and ecosystem variations over the past 12,000 years.

The scientists identified significant cycles lasting 200, 435, 590 and 950 years
in the 12,000-year record, which are consistent with previously recognized
cycles of solar activity. By comparison of the Alaskan subarctic record to
recent findings of North Atlantic ice cover variations and
solar-activity-modulated production records of beryllium-10 and carbon-14, the
scientists showed that the changes in sub-polar climate and ecosystems are
correlated with records related to slight variations in solar irradiance.

The data from biogenic silica, North Atlantic sea ice, and beryllium-10 and
carbon-14 showed "remarkable correlation during the cycles", Brown said.

"We found natural cycles involving climate and ecosystems that seem to be
related to weak solar cycles, which, if verified, could be an important factor
to help us understand potential future changes of Earth's climate," said
principal investigator Feng Sheng Hu of the University of Illinois at Champaign-
Urbana.

"Will changes in solar irradiation in the future mitigate or exacerbate global
warming in the future? They may do both. A period of high solar irradiance on
top of high levels of greenhouse gases could result in unprecedented warming."

Other contributors come from Northern Arizona University, the Weizmann Institute
of Science in Israel, Brown University and Columbia University.

Founded in 1952, Lawrence Livermore National Laboratory is a national security
laboratory, with a mission to ensure national security and apply science and
technology to the important issues of our time. Lawrence Livermore National
Laboratory is managed by the University of California for the U.S. Department of
Energy's National Nuclear Security Administration.