Tuesday, December 13, 2016

Severe melting of ice sheet is found in Antarctica


By Chris Mooney Washington Post December 12, 2016

A team of European scientists has found a significant amount of ice sheet melting in East Antarctica during the summer months, in an area that is supposed to be too cold for perceptible ice loss.

The researchers also found that the ice shelf was anything but solid — it had many large pockets of weakness throughout its structure, suggesting a greater potential vulnerability to collapse through a process called ‘‘hydrofracturing.’’


But East Antarctica is supposed to be different. It is extremely remote and cold and doesn’t generally see such warm temperatures in summer, so its ice tends to remain more pristine.

‘‘Many people refer to East Antarctica as being too cold for significant melt,’’ says Jan Lenaerts, a glaciologist with Utrecht University in the Netherlands. ‘‘There’s marginal melt in summer, but there’s not a lot.’’

That common wisdom has been challenged in the study by Lenaerts and his colleagues. On the very large Roi Baudouin ice shelf in East Antarctica, which floats atop the ocean, they found a very Greenland-like situation in early 2016.


The researchers are not saying that these processes are caused by human-induced climate change — they note in particular that on the Roi Baudouin shelf, it appears there has been some melting at the surface since the 1980s.
[Global warming has been going on before 1980.

However, Lenaerts said, it is already clear there is much more melt water during warmer summers than in cooler ones. And global warming will gradually produce warmer Antarctic temperatures, which should increase the volume of melt water atop these ice shelves, pushing them still further in the Greenland direction.

This means the shelves could be subject to the risk of hydrofracturing, in which a great deal of meltwater forms atop the shelf and pushes inside of it, eventually leading to a crackup.

That’s what is believed to have happened in the classic case of the shattering of the Larsen B ice shelf in the Antarctic peninsula in 2002. The fear is that it could happen in the East Antarctic too, where there is a massive amount of ice to potentially lose.

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