A major Antarctic ice sheet, once believed to be stable, is anything but…
Warming waters from the southern Indian Ocean are slipping under the Totten Ice Shelf in East Antarctica and thinning the ledge from below. The Totten Shelf, which sits on on the coast and floats on the waster, holds back the massive East Antarctic glacier, an ice sheet about the size of the continental United States.
Because the ice shelf appeared to be stable when observed from about, scientists believed that the ice shelf and the sheet behind it were stable. Recent observations on the ground suggest that the shelf has been thinning for the past few decades.
The Totten shelf appears to be following the same basic scenario as the Larsen A, B and C shelves, all of which have collapsed in the past 20 years.
Ice shelves are a sort of hybrid between the vast ice sheets that cover Greenland and Antarctica and sea ice, which floats in the polar regions. What makes ice shelves interesting to scientists is the fact that they serve to hold back the continent-sized glaciers behind them. When ice shelves collapse, as the Larsen C shelf did earlier in 2017, the glaciers behind them “speed up”, accelerating their flow into the oceans. When land ice flows into the sea and melts, it contributes significantly to sea level rise because the water/ice has not previously been in the ocean.
If the East Antarctica ice sheet melted, it would raise sea levels globally up to 60 feet.