Aerial view of the polynya in the Southern Ocean. Credit: Jan Lieser, ACE CRC, Australia
Something very strange just happened in Antartica. An enormous hole in the sea ice just opened up for no apparent reason, and researchers are at a loss as to why it might’ve happened. The hole, known as a polynya, is a strange phenomenon where a region of open water shows up in the middle of the sea ice in the Arctic and Southern Oceans. The one in question is called the Weddell polynya, and it’s more than 16,000 square miles.
Antarctica is still in the clutches of winter, and the Weddell Sea is usually still covered in sea ice. Despite the freezing temperatures, however, the polynya is making a break for it. Back in the ’70s, scientists studying the area first noticed the Weddell polynya. It’s strange for one very good reason: while most polynyas occur near coastlines, the Weddell is far inland and relatively sheltered from the violent winds and turbulent seas that generally cause them. It’s in an area called the Maud rise, and when those scientists first saw it, it was the size of Oregon. Over the next two years, in 1975 and 1976, it showed up again. Until now, the area has remained frozen over.
In the winter of 2016, a much-diminished Weddell showed up again on satellite images. While far smaller than it was in the ’70s, it was still interesting since it hadn’t been around for over four decades. “While many climate models tend to produce such a large open ocean polynya, the feature was viewed more as a disruptive model glitch than a true phenomenon in the past,” Torge Martin, a meteorologist and climate modeler at the Helmholtz Centre for Ocean Research in Kiel, Germany, said. “Its recurrence supports our hypothesis… that the Weddell Polynya was not a one-time event but possibly occurred regularly in the past.”
Now, in 2017, it has considerably increased in size. At 16,000 square miles, the 2017 Weddell polynya is roughly the size of Switzerland, and it’s thought to be “driven by the upwelling of warm water, which releases heat to the air, before becoming cooler and denser, and sinking.”
“The polynya is like a big window,” Martin told Earther. “Through the hole in the ice heat escapes from the ocean, warming the atmosphere above but more so cooling the ocean underneath. We really don’t know what’s going on. We don’t have enough observations of the Southern Ocean yet.”
Studying the massive hole in the sea ice might help us understand more about the Antarctic circulation, which plays a large role in the planet’s climate.
“There’s a bit of a mystery going on in Antarctica at the moment,” said Céline Heuzé, a physical oceanographer at the University of Gothenburg, Sweden, to Earther. “From global circulation, we know how much deep water should be formed, but the areas we know are forming water now just aren’t forming enough. We’ve got a source of deep water that’s missing, somewhere. Maybe [the Weddell polynya] contributes to that.”
Source: The Inertia