What's up with these deep gashes in the Antarctic ice?

During the austral winter, which extends From June to September, Antarctica is lined with nearly seven million square kilometers of ice. For several decades, scientists have examined satellite images of these frozen windrows and noticed blue-black cavities where water and ice open to the air and the sky. These jagged holes are known as polynyas and can be huge. In 2016 and 2017, hacks in the Weddell Sea had appeared. over 13,000 square miles wide. They persist even in the icy and windy darkness, when the temperatures drop fiercely. -58 degrees Fahrenheit.

We still do not know much about these pits: we do not yet know, for example, how they affect the atmosphere – they can release carbon dioxide that had stagnated and stored in the depths of the ocean – and we do not know what they mean for the creatures swimming inside of them. (Arctic analogues, for example, become oases rich in food.) In the Antarctic, scientists continue to question an even more fundamental question: how on earth do these holes get there?

To answer this question, a team led by researchers from the University of Washington took a creative approach that espoused different perspectives, ranging from deep diving to soaring. The research, recently published in Nature, was co-written by scientists from the Scripps Institution of Oceanography and assisted by satellite imagery, floating sensors and an elephant seal brigade equipped with instruments attached to the head.

The researchers had a stroke of luck when some of these tanks, deployed as part of the carbon and climate observations and modeling project in the Southern Ocean, found themselves near Maud Rise, a underwater mountain where satellites had captured images of polynyas in recent years. When the researchers took a closer look at what was happening in the water, they concluded that the polynyas appear due to a "combination of factors that must occur at the same time," says Ethan Campbell, graduate student in oceanography at the University of Toronto. Washington and lead author of the study.

The team found that around the mountain, warmer and saltier waters from deeper depths are pushed back to the surface. Then, when the storms arrive, a "deep, violent, vertical" mix begins, Campbell explains, which causes a continuous brewing of the water column. All of this creates a pattern that repeats itself over and over, according to NASA Earth Observatory, until the air warms a little in the spring or a clearer, cooler water appears at the top. The research picks up some aspects of the previous results: a separate recent study which attributes the Maud Rise 2017 polynya to polar cyclones, which destroy the ice, this team found that "storms are essential," says Campbell.

Campbell and his collaborators found that all of these things worked together – winds, warm, salty water rushing to the surface, then chilling and steadily sinking into a churn – giving rise to polynyas. "Every year, many of these things could happen, but if you do not have them all, you do not get polyny," said co-author Stephen Riser, oceanographer, in a statement.

American scientist reported there is still much to be learned about what will happen to the holes as the climate changes – melting glaciers could add a stream of fresh water, for example, which could make the water less likely to turn around, but an increasingly violent wind could exacerbate the flow. For the moment, at least, the researchers are closer to understanding exactly how the Antarctic polynya appear.