Winter no relief

Wilkins Ice Shelf continues disintegration

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.