9 october 2019

How Antarctica is melting from above and below

Upside-down rivers lapping at the bottoms of ice sheets and brilliant blue mini-lakes dotted on top may be speeding up Antarctic melting.

By Madeleine Stone, National Geographic, October 9, 2019

The frozen mountains and icy plains of Antarctica hold enough water to raise global sea levels nearly 200 feet. Thankfully, over three-quarters of the continent is girded by ice shelves, the floating extensions of glaciers that protect the land-bound ice behind them like walls surrounding a vast, icy castle. But scientists are discovering new vulnerabilities that could weaken those walls from above and below.

In the frigid realm of East Antarctica, tens of thousands of brilliant blue lakes are forming across ice shelves in the summertime—far more than scientists previously realized, according to a study published last month in Scientific Reports. Meanwhile, in rapidly-melting parts of West Antarctica, “upside down rivers” of warm water are gnawing away at the ice shelves’ weak spots from below, according to a study published Wednesday in Science Advances.

As the Earth continues to warm, both processes could hasten the demise of Antarctica’s icy armor and the giant glaciers it holds back.


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