The mysterious reason for holes forming in the Antarctic ice

Between 2016 and 2017, the appearance of huge and inexplicable holes in the middle of the Antarctic ice has generated a great stir and many questions in the world. After a special investigation, it has been determined that this phenomenon is produced by a series of ocean anomalies.

The winter ice on the surface of the Weddell Sea in Antarctica sometimes forms large holes. In August 2016, a satellite image of NASA revealed a gap of 33,000 km 2 over three weeks. In 2017, another hole of 50,000 km2 emerged. To find an explanation, the University of Washington combined satellite images of sea ice cover with robotic dinghies and even seals equipped with sensors to better understand the phenomenon, called polynya (hole in the ice, in Russian) , which occurs when the wind pushes the ice near the coast.

The observations showed that they had opened because of a combination of factors, "one of them is the unusual situation of the ocean and the other, a series of very intense storms that have invaded the Weddell Sea with almost hurricane winds ". The new study used observations from the Southern Ocean Carbon and Weather Modeling and Observation Project, which emits current-derived instruments to monitor Antarctic conditions, and collected data from the Antarctic program. observation of Argo oceans, elephants that transmit data on the coast, weather stations and decades of satellite images. "This polynya is caused by a series of factors that must all be harmonized to make it happen," said Stephen Riser, a key research participant.

The winds around Antarctica are getting closer to the coast, favoring a more intense brewing in the East Weddell Sea. There, an underwater mountain forces the dense water that surrounds it and leaves a whirling swirl at the top. Heavy winter storms can trigger a change in circulation: the warmer, saltier waters of the depths are shaken to the surface, where the air cools them and makes them denser than groundwater. By flowing, a relatively warm deep water, to a degree Celsius, replaces it, creating a feedback loop where the ice can not be restored.

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