Rapid Antarctic Ice Loss
Pastor Dale Morgan
Rapid Antarctic Ice Loss*
Satellite-derived image of the surface topography of Antarctica. Shown
in color are the flow speeds of glaciers draining ice into the oceans.
The scale is meters per year. It is noticeable how the rate speeds up in
narrow glacier outlets. Credit: Jonathan Bamber
by Staff Writers
Bristol, UK (SPX) Jan 14, 2008
Increasing amounts of ice mass have been lost from West Antarctica and
the Antarctic peninsula over the past ten years, according to research
from the University of Bristol and published online this week in Nature
Geoscience. Meanwhile the ice mass in East Antarctica has been roughly
stable, with neither loss nor accumulation over the past decade.
Professor Jonathan Bamber at the University of Bristol and colleagues
estimated the flux of ice from the ice sheet into the ocean from
satellite data that cover 85% of Antarctica's coastline, which they
compared with simulations of snow accumulation over the same period,
obtained using a regional climate model.
They arrived at a best estimate of a loss of 132 billion tonnes of ice
in 2006 from West Antarctica - up from about 83 billion tonnes in 1996 -
and a loss of about 60 billion tonnes in 2006 from the Antarctic Peninsula.
Professor Bamber said: "To put these figures into perspective, four
billion tons of ice is enough to provide drinking water for the whole of
the UK population for one year."
The authors conclude that the Antarctic ice sheet mass budget is more
complex than indicated by the evolution of its surface mass balance or
climate-driven predictions.
Changes in glacier dynamics are significant and may in fact dominate the
ice sheet mass budget. This conclusion is contrary to model simulations
of the response of the ice sheet to future climate change, which
conclude that it will grow due to increased snowfall.
The ice loss is concentrated at narrow glacier outlets with accelerating
ice flow, which suggests that glacier flow has altered the mass balance
of the entire ice sheet.
Over the 10 year time period of the survey, the ice sheet as a whole was
certainly losing mass, and the mass loss increased by 75% during this
time. Most of the mass loss is from the Amundsen Sea sector of West
Antarctica and the northern tip of the Peninsula where it is driven by
ongoing, pronounced glacier acceleration. In East Antarctica, the mass
balance is near zero, but the thinning of its potentially vulnerable
marine sectors suggests this may change in the near future.