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Not even the Antarctic winter can save the Wilkins Ice
Shelf.
The European Space Agency reported earlier this month
that the ice shelf is continuing to deteriorate over the
austral winter, with an area of about 160 square kilometers
breaking off from May 30 to 31. ESA’s Envisat satellite
captured the event — the first ever-documented episode
to occur in winter.
The Wilkins Ice Shelf, a broad sheet of floating ice
along the Antarctic Peninsula, is connected to two islands,
Charcot and Latady. In February 2008, an area of about
400 square kilometers broke off from the ice shelf. The
National Snow and Ice Data Center (NSIDC) in Boulder,
Colo., which is partly funded by the National Science
Foundation, first reported the collapse. (See related
story: Breaking up.)
According to Matthias Braun from the Center for Remote
Sensing of Land Surfaces, Bonn University, and Angelika
Humbert from the Institute of Geophysics, Münster
University, who have been investigating the dynamics of
Wilkins Ice Shelf for months, this break-up has not yet
finished.
“The remaining plate has an arched fracture at its
narrowest position, making it very likely that the connection
will break completely in the coming days,” Braun
and Humbert said.
Braun and Humbert are monitoring the ice sheet daily
via Envisat acquisitions as part of their contribution
to the International Polar Year (IPY), a worldwide science
program focused on the Arctic and Antarctic.
The Wilkins disintegration won’t raise sea levels
because it already floats in the ocean, and few glaciers
flow into it. However, NSIDC scientists and others have
previously noted that the collapse appears to be part
of a pattern, and additional ice shelves in the region
may be at risk. Several have retreated in the past 30
years, with six of them collapsing completely — Prince
Gustav Channel, Larsen Inlet, Larsen A, Larsen B, Wordie,
Muller and the Jones ice shelves.
The Antarctic Peninsula has arguably experienced the
most dramatic rise in temperature over the last 50 years.
NSIDC said temperatures have climbed 0.5 degrees Celsius
each decade. Other scientists with the U.S. Antarctic
Program have said the overall increase is about 6.5 degrees
Celsius in the winter since the 1950s, rising more than
five times faster than the global average.
ESA is helping scientists during IPY to collect an increasing
amount of satellite information, particularly to understand
recent and current distributions and variations in snow
and ice and changes in the global ice sheets.
ESA is also co-leading a large IPY project — the
Global Interagency IPY Polar Snapshot Year (GIIPSY) —
with the Byrd Polar Research Center . The goal of GIIPSY
is to make the most efficient use of Earth-observing satellites
to capture essential snapshots that will serve as benchmarks
for gauging past and future changes in the environment
of the polar regions. (See related story: The whole picture.)
Long-term satellite monitoring over Antarctica is important
because it provides authoritative evidence of trends and
allows scientists to make predictions. Ice shelves on
the Antarctic Peninsula are important indicators for on-going
climate change because they are sandwiched by extraordinarily
rising surface air temperatures and a warming ocean.
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