A mysterious hole the size of Switzerland is forming in the same place in Antarctica, and now scientists have found an explanation

For decades, scientists have noticed the formation of a hole the size of Switzerland in the Antarctic ice, without even having an explanation for this phenomenon. Now, after 50 years, they finally have an answer to this dilemma.

Researchers first noticed the hole, christened the Maud Rise polynya, in 1974 and 1976 in the Weddell Sea in Antarctica, and since then it has reappeared fugitively and sporadically, each time having different sizes, but forming in the same place, writes Live Science.

However, interestingly, the hole did not always form, which means that some special conditions are needed for this to happen.

In 2016 and 2017, the huge, 80,000 square kilometer hole formed again and remained so for several weeks during both winters, allowing scientists to study the phenomenon.

“2017 was the first time we’ve had such a large and long-lasting hole in the Weddell Sea since the 1970s,” said study lead author Aditya Narayanan, a researcher at the University of Southampton in England.

When summer turns to winter in Antarctica, the sea ice expands from about three million square km to 18 million square km, covering 4% of the Earth’s surface.

Holes in this ice, called polynyas, form when strong winds from within push the plates outward. The cold wind also freezes more seawater inside them, adding extra chunks to the ice sheet.

But in the open ocean and away from these coastal winds, holes in the sea ice are much less likely to develop. And yet this hole appeared. This, along with a stunning reduction in the total extent of ice in the Southern Ocean, has led scientists to wonder what specific conditions could cause the formation of the Maud Rise.

To investigate the mystery, scientists analyzed data from satellites, as well as previous observations made by other researchers. They found that in 2016 and 2017, the Weddell Sea’s circular ocean current, called the Weddell Gyre, was stronger than in other years, helping underwater currents bring salt and heat closer to the surface. Not coincidentally, the hole is located near Maud Rise, an underwater mountain.

The new discovery is important for understanding Antarctica and its impact on the global ocean, researchers say. Climate change is already making winds on the southernmost continent stronger, likely creating more such holes in the future.