Free Thinking

Large Iceberg Looks Poised to Break Off from Antarctica – Scientific American | Jan 2017

January 2017

A chunk of ice bigger than New York’s Long Island is hanging on by a relative thread

The stability of ice shelves is important because they help buttress the huge glaciers that feed them. When an iceberg calves off an ice shelf, there is less ice to push back on the glaciers, causing them to speed up. In a stable system, the front of the ice shelf eventually moves forward until the whole system is once again in balance.
While calving is a natural process, it can be driven into overdrive by the warm ocean waters that are lapping away at the ice shelves that fringe Antarctica. When calving events happen too quickly in succession, the glacier-ice shelf system doesn’t have time to rebalance, which can result in glaciers continuing to speed their flow, bringing more and more ice into the oceans and raising sea levels.
This is what happened with Larsen C’s northern neighbors, Larsen A and B, which collapsed spectacularly in 1995 and 2002, respectively. The glaciers that had fed Larsen B flowed six times faster after its demise.
The world’s oceans have already risen by an average of 8 inches over the last century from a combination of water added by ice melt and the expansion of ocean waters as they warm. The entire West Antarctic Ice Sheet, of which Larsen C is a part, holds enough ice to raise sea levels by another 10 to 13 feet if it were all to melt.
    By Andrea Thompson, Climate Central on January 6, 2017