Global Warming

Antarctica’s sea ice is mysteriously melting, and fast

After mysteriously expanding for decades, Antarctica’s sea ice cover melted by an area four times greater than France in just a few years and now stands at a record low, according to a study published Monday.

Scientists already knew Antarctica was thawing at an increasing rate, like the Arctic, because of accelerating discharge from glaciers, the rivers of ice that push up slowly against the shore. But between 1979 and 2014, they observed a phenomenon that was both intriguing and reassuring: the sea ice cover was expanding.

From 2014 to 2017, however, “the Antarctic lost almost as much as the Arctic” over almost 40 years, Nasa climatologist Claire Parkinson said, and the trend has continued ever since.

From a peak area of 12.8-million km2, the sea ice cover receded 2-million km2 for reasons that remain unknown. “It went from its 40-year high in 2014, all the way down in 2017 to its 40-year low,” said Parkinson, whose findings were published in the Proceedings of the National Academy of Sciences (PNAS).

The Arctic is an ocean surrounded by land, while Antarctica is a continent surrounded by oceans, where icebergs are less constrained. Unlike the Arctic, Antarctica is not warming and remains the coldest place on Earth, as well as its largest source of freshwater. Its mountains are covered in ice are capable of raising the level of the oceans by 57m, according to a 2013 study.