news
release May
19, 2005
Contacts: Heather Emmons, DRI PIO, heather.emmons@dri.edu, Reno
(775) 673-7313 (w), (702) 743-3435 (c)
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Growth in East Antarctic Ice Sheet from Increased Snowfall Mitigates
Sea-Level Rise, DRI-MU Study Finds
Results reported
in online edition of Science.
Dr. Joseph McConnell The
field team traverses across West Antarctica. Co-author
and University of Arizona
Graduate
Student Markus Frey takes
samples
in West Antarctica.
RENO, Nev. – Current
estimates indicate that sea level worldwide is increasing due to global warming
and shrinkage of terrestrial, or land-based, ice. In
a new study appearing in this week’s online edition of Science, research
led by the Desert Research Institute in Nevada and the University of Missouri-Columbia
found that the interior of the East Antarctic ice sheet is actually gaining mass
and that this increase is likely due to increased accumulation of snowfall. The
mass gain is enough to slow sea-level rise by 0.12 millimeters per year.
This conclusion was based on two key results. First,
Curt Davis, MU professor of electrical and computer engineering, and his team
of researchers used satellites to observe changes in elevation for 7.1 million
square kilometers of the Antarctic ice sheet from 1992 to 2003. They
discovered that the ice sheet’s interior was gaining mass by about 45 billion
tons per year. The researchers used radar altimeters
from the European Space Agency’s ERS-1 and ERS-2 satellites to make 347
million elevation-change measurements during the study period.
Second, Joe McConnell, DRI professor of hydrology, and his team compared the
elevation change results with modeled precipitation in the region. This
work suggests that the mass gain in East Antarctica is likely due to increased
precipitation during the study period, a finding consistent with the most recent
report from the U.N. Intergovernmental Panel on Climate Change.
“The interior of the East Antarctic ice sheet is the only large terrestrial
ice body that is likely gaining mass rather than losing it,” according
to Davis. Other scientific studies have shown that
a variety of terrestrial ice sources—such as the Greenland ice sheet, the
West Antarctic ice sheet and Alaskan mountain glaciers—are contributing
significant amounts to global sea-level rise.
Davis adds, “This study suggests that the interior areas of ice sheets
also can play an important role. In particular, the
East Antarctic ice sheet is the largest in the world and contains enough mass
to change sea level by more than 50 meters. Thus,
only small changes in its interior can have a significant affect on sea level.”
McConnell cautions, however, that “governments around the world should
take sea-level rise from global warming very seriously because the economic and
environmental costs will be huge. Our study is specific
to the time period 1992 to 2003. Although some climate
models predict that precipitation will continue to increase in the future as
the Earth warms, there are no guarantees.” He
adds, “We need more ice core measurements from East Antarctica and better
long-term precipitation modeling to determine if this increased precipitation
is a change from the past or part of natural variability.”
Study results did not assess the overall contribution of the entire Antarctic
ice sheet to sea-level rise. Other recent studies
have shown that coastal areas of the West Antarctic ice sheet are losing large
amounts of mass. “Ice sheet response to climate
change is a complex process that is difficult to measure and even more difficult
to predict,” Davis said. “The overall
contribution of the Antarctic ice sheet to global sea-level change will depend
on how mass changes in the ice sheet’s interior balance mass changes from
coastal areas.”
Davis’ study of the mass increase was funded by
NASA’s Cryospheric Processes Program, and McConnell’s work suggesting that
increased precipitation was the likely cause of the gain was supported by both
NASA and the NSF Antarctic Glaciology Program.
The article can be viewed at: http://www.sciencemag.org/sciencexpress/recent.shtml
A nonprofit, statewide division of the University and Community College System
of Nevada, DRI pursues a full-time program of basic and applied environmental
research on a local, national, and international scale. Nearly 500 full- and
part-time scientists, technicians, and support staff conduct more than 300 research
projects at DRI annually. DRI generates $45 million in total revenue consisting
predominately of competitively won research contracts and grants. The State of Nevada
provides
critical funding in support of DRI's administration, operations and maintenance,
through the University and Community College System of Nevada budget. While
DRI’s
portion of the UCCSN budget is less than 1 percent, the institute leverages
these funds to enhance its competitiveness.
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