Scientists discovered that a 300,000-square-mile portion—an area twice the size of California — of the West Antarctic Ice Sheet perimeter had melted into slush.
Their research suggests that an unusually strong El Niño event around January 2016 was to blame. And it has frightening implications for the future of the ice sheet, because it means that not just warming sea temperatures are causing melting, but the atmosphere above is contributing as well – the ice sheets are melting from the top and the bottom.
“A melt of this magnitude is relatively rare in Antarctica,” said Julien Nicolas, of the Ohio State University Byrd Polar and Climate Research Center, and one of the Nature Communication study’s authors. “There have been about three or four events of this size in the last 40 years.” Even more unexpected, the scientists observed rain.
“We saw in our observations that there were some rain, we heard from some parties on the Ross Ice Shelf, and we saw it on the weather models,” Nicolas said. “That’s very unusual. We don’t have a record of rain in Antarctica, so we don’t know how often it’s happened in the past.”
“When it comes to the disintegration of the ice shelves, they are like corks in a bottle,” says Dr. David Bromwich, another author of the paper and a professor at the Ohio State. “They are holding back the contents of the bottle, in this case the ice sheet, and you take the cork away and everything flows out to the ocean.”
“We don’t know the time scale of this,” he said. “There was one modeling study that showed quite dramatic changes on the scale of a few hundred years, and another scenario would be quite a slow change. But a foot of sea rise, or two feet, in the order of 100 years would be alarming.”
Watch as this time-lapse satellite imagery captures two icebergs breaking off the continent in 2016: