palo alto [CSL Colloq] A Global Climate Model Projection of Severe Degradation of * 4:15PM, Wed April 5, 2006 in Gates B01

[David Farber <dave () farber net>]

Begin forwarded message:

From: allison () stanford edu
Date: April 1, 2006 10:16:45 AM EST
To: dave () farber net
Subject: [CSL Colloq] A Global Climate Model Projection of Severe  
Degradation of * 4:15PM, Wed April 5, 2006 in Gates B01
Reply-To: ee380 () shasta stanford edu



             Stanford EE Computer Systems Colloquium

                 4:15PM, Wednesday, April 5, 2006
        HP Auditorium, Gates Computer Science Building B01
                   http://ee380.stanford.edu[1]

Topic:    A Global Climate Model Projection of Severe Degradation of
          Near-Surface Permafrost: Potential Feedbacks on Climate

Speaker:  David Lawrence
          National Center for Atmospheric Research

About the talk:

In recent decades, the Arctic has witnessed significant
environmental change ranging from decreases in sea ice extent,
increases in shrub cover and melting glaciers. Temperatures over
Arctic land are rising at roughly twice the rate of the rest of
the world. Permafrost, which is defined as soil or rock that
remains below 0oC for two or more years, is an archetypal
component of the Arctic climate system. In harmony with other
aspects of change, permafrost temperatures are rising and there
have been reports of significant permafrost degradation in some
locations.
Results from the NCAR Community Climate System Model (CCSM3)
indicate that degradation of permafrost will continue and may
accelerate during the 21st century. The CCSM3 is a mathematical
model of the global climate system that includes components
representing the atmosphere, ocean, land, and sea-ice. The land
model component is limited to simulating the top 3.5m of the
ground, though this is the ecologically and hydrologically
important portion; deeper permafrost is not as vulnerable at the
century timescale. The present-day global distribution of
near-surface permafrost in the CCSM3 compares well with observed
estimates of permafrost distribution both in terms of
geographical extent and total area (~10.5 million km2).
Projections of the fate of near-surface permafrost are assessed
through simulations of the 21st century climate under various
greenhouse gas emission scenarios provided by the
Intergovernmental Panel on Climate Change (IPCC). Under the
"business as usual" emission scenario (A1B), the area containing
permafrost in the near-surface layer declines by ~80% by 2100.
Under a lower emission scenario (B1), the degradation of
permafrost is less severe (~60%) but still substantial.
There are considerable uncertainties in both the magnitude and
the timing of the projected near-surface permafrost degradation
due to deficiencies in the model that include biases in the
simulated climate, an imperfect land model, and feedbacks that
are not fully-represented in the model. Nonetheless, this result
in conjunction with the observed permafrost warming across the
Arctic suggests that large-scale changes in permafrost are
likely. The potential climate feedbacks associated with a
degradation of near-surface permafrost are diverse. Changes to
Arctic vegetation, hydrology, and the carbon cycle are expected
in the form of expanding shrub cover and northward forest
migration, enhanced runoff to the Arctic Ocean as well as
expanding and retreating lakes and wetlands, and the release of
large quantities of soil carbon, currently frozen in permafrost
soil, into the atmosphere. These feedbacks could contribute to an
acceleration of global climate change.

About the speaker:

Dr. David Lawrence is a research scientist at the National Center
for Atmospheric Research (NCAR) in Boulder, Colorado. His
research interests are centered around land-atmosphere
interactions and improving our understanding of the role of land
surface processes in the Earth’s climate system and their
influence on climate change. He is involved in the assessment and
development of NCAR’s Community Climate System Model (CCSM) and
is co-chair of the CCSM Land Model Working Group. Previously he
completed a post-doc at the Department of Meteorology at the
University of Reading in the United Kingdom. He received his
Ph.D. in 1999 from the Department of Atmospheric and Oceanic
Science at the University of Colorado.

Contact information:

David Lawrence
P.O. Box 3000
Boulder, CO 80307
303 497-1384
303 497-1348
dlawren () ucar edu[2]


Embedded Links:
[ 1 ]    http://ee380.stanford.edu
[ 2 ]    mailto:dlawren () ucar edu


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