1,500 meter deep ditch accelerates glacier melt

The warming ocean penetrates over glacial forests into the interior of the West Antarctic

A researcher pulls the sled with the radar over the ice of the Ferrigno glacier. © British Antarctic Survey
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A particular geographic formation could be responsible for the rapid melting of the western Antarctic. Hidden beneath the Ferrigno Glacier, British scientists have discovered a trench underground that is up to 1, 500 meters deep. This incision extends to the coast and is there connected to the warming ocean. As a result, he could intensify the melting of the ice far into the interior of the continent, the researchers report in the journal "Nature". Even today, the West Antarctic contributes around ten percent of the world's sea-level rise. Therefore, the researchers hope that their discovery can predict the future increase more accurately.

With glaciers shrinking to a meter per year, the West Coast loses more ice than any other Antarctic region. "To understand why some glaciers, such as the Ferrigno ice stream, melt away very quickly, we had to study the conditions under the ice cover, " explains Robert Bingham, a glaciologist at the University of Aberdeen.

Geographical data of the area around the Ferrigno glacier were first recorded in 1961. Only now, fifty years later, have scientists re-entered the ice landscape on the Arctic west coast to deepen these measurements. The British research team spent three months illuminating the 14, 000-square-meter ice rink with radar slides. In order to map the trench system close to reality, they also determined gravitational changes and magnetic waves within the study area.

Underground elevation map under the Ferrigno Glacier © British Antarctic Survey

The Grand Canyon of the Antarctic

After evaluating their data, the scientists were given a new geographical picture of the Arctic coastal region: beneath the ice sheets of the Ferrigno glacier lies a million-year-old tectonic fault that the glacier scraped over time to a trench that is up to 1, 500 meters deep. "If you blew the ice there today, you might see a formation approaching the Grand Canyon in size, " says Bingham.

For the Antarctic, the geographical particularity has far-reaching consequences, the scientists report. On the one hand, the geothermal heat rising from the earth's crust accelerates the melting of the deeper ice layers. On the other hand, the ditch today connects the Sûdpolarmeer with the Ferrigno Glacier. As a result, the warming seawater penetrates up to the ice masses inland and additionally strengthens the melt. display

Glacier melt is more than a consequence of climate change

"The changes observed in the Antarctic today not only show a short-term response to global warming, " concludes British scientists. Rather, these are part of a much wider interaction between the activity of the continental plates, the transformation of the glacier landscapes, as well as ultimately oceanic and atmospheric changes. With West Antarctic already accounting for around ten percent of global sea-level rise, their study helps to better understand this relationship. The researchers hope to be able to predict the future increase in the oceans more accurately. (Doi: 10.1038 / nature11292)

(Nature, 26.07.2012 - ILB)