Time to re-adjust sea level rise estimates
New measurements taken in the ocean near a massive East Antarctica ice sheet confirm that warm water is melting the ice from below. The new data will help scientists determine how fast the Totten Ice Shelf will melt. In all, it contains enough water to raise global sea level by 3.5 meters, according to a new study published last week in Science Advances.
Previous studies have suggested that Antarctic ice shelvesare thinning because of warming ocean temperatures. The fastest melting, as well as an acceleration of glaciers, has been reported from the Bellingshausen Sea and the Amundsen Sea, where much of the ice sheet rests on bedrock below sea level that deepens upstream.
That, according to the new study, is “a potentially unstable configuration that may result in rapid glacial retreat and mass loss to the ocean … Models and observations suggest that increased ocean heat flux may have already initiated the unstable retreat of some West Antarctic glaciers.”
Warm ocean water makes its closest approach to Antarctica in these regions, helping to explain the rapid mass loss from the West Antarctic Ice Sheet, which is considered susceptible to unstable retreat, but the East Antarctic Ice Sheet was assumed to be more stable. But the researchers said that sea level rise of more than 10 meters in past eras means that there must have been significant melting of the East Antarctic ice sheet.
The Totten Glacier drains more ice than any other glacier in the East Antarctic Ice Sheet, occupying a deep fjord that connects to inland regions. The study concluded that there is significant evidence that warm water is penetrating a cavity in the ice through a deep channel, which means the Totten Glacier is melting from the inside-out.