How Ice-Shelf Loss Leads to Faster Sea-Level Rise in Antarctica

It turns out that ice-shelf loss will lead to faster sea-level rise. Scientists have taken a closer look at ice shelves and have found that we may be in for rising waters.

Antarctica is surrounded by huge ice shelves. The largest of these, the Ross Ice Shelf, has an area comparable to the size of Spain. These ice shelves are several hundred meters thick and float on the surface of the sea, towering above the water. They are firmly linked to glaciers and ice streams on mainland Antarctica, and are naturally fed by upstream inflow from tributary glaciers which push the floating ice seawards.

In the past 20 years, though, there's been a progressive retreat and break-up of ice shelves on the Antarctic Peninsula. In 1995, Larsen A Ice Shelf collapsed completely, removing the ice-cover from an area the size of Berlin. Seven years later, the much larger Larsen B Ice Shelf broke apart. This disintegration had hardly any immediate effect on sea levels since the ice was already afloat.

If all ice shelves surrounding Antarctica were to collapse, this would result in rapid dynamic loss of inland ice, which would entail an elevated Antarctic contribution to sea-level rise for decades to come.

"As ice shelves continuously lose ice by calving, it is essential to know how far the recession of ice shelves may progress before the buttressing potential is reduced," said Johannes Furst, one of the researchers, in a news release.

The researchers found that 13 percent of the total ice-shelf area contains "passive shelf ice." This is the part of the floating ice body which provides no additional buttressing and when lost will not trigger a velocity increase. However, this part of the ice-shelf area is rapidly disappearing.

"We expect that further ice-shelf retreat there will instantly produce dynamic changes, which may well give rise to increased ice outflow from the mainland," said Furst.

The findings are published in the journal Nature Climate Change.

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