The satellite has been keeping an eye on the Southern Continent for a decade

Apr 5, 2012 09:43 GMT  ·  By

The European Space Agency's (ESA) Envisat spacecraft is in a unique position to reveal the extent of ice loss going on in Antarctica. The satellite has been studying the Southern Continent for more than a decade, and the datasets it obtained since then are now being scanned for long-term trends.

ESA has been using Envisat to monitor what goes on at the South Pole ever since the satellite was launched, on March 1, 2002. Just after it reached orbit, the spacecraft observed the brake-up of a massive chunk of the Larsen B ice shelf in Antarctica.

Within just a few days, no less than 3,200 square kilometers (1,235 square miles) of ice broke off from the ice sheet, primarily due to mechanical instabilities induced by rising temperatures. Warming affects areas at the poles more than the Equator, and this accounts for the weaker ice integrity.

Over the past decade, an additional 1,790 square kilometers (692 square miles) of ice were lost from Larsen B. Envisat tracked all instances of calving from orbit, using its Advanced Synthetic Aperture Radar (ASAR) instrument.

This particular ice sheet is part of a three-shelve system, which includes Larsen A and Larsen C, with the latter being the largest. All of them are located on a north-south axis on the eastern seaboard of the Antarctic Peninsula.

Larsen A has long since disappeared. It disintegrated back in 1995, about six years before Envisat's launch. Larsen C fortunately proved to be more stable, but recent data indicate that it is beginning to lose structural integrity as well.

The satellite determined that the duration of standard ice melt events – which occur during the Antarctic summer – is increasing. This phenomenon contributed to thinning the Larsen C ice sheet.

“Ice shelves are sensitive to atmospheric warming and to changes in ocean currents and temperatures,” explains University of Innsbruck expert, professor Helmut Rott.

“The northern Antarctic Peninsula has been subject to atmospheric warming of about 2.5°C over the last 50 years – a much stronger warming trend than on global average, causing retreat and disintegration of ice shelves,” he adds.

In January 1995, Larsen B covered an area of 11,512 square kilometers (4,444 square miles). An Envisat scan conducted earlier this year shows the ice sheet to extend over 1,670 square kilometers (644 square miles), which means that its area decreased 7 times in just 17 years.