A band of clouds in an atmospheric river that stretched from South America to the Antarctic sea ice zone in 2017
Rivers of warm air transported through the atmosphere have been found to play an important role in creating large openings in the Antarctic sea ice.
Storms are known to trigger the openings known as polynyas, which in the past have expanded to tens of thousands or even hundreds of thousands of square kilometers. But while the world’s strongest storms occur regularly in the Southern Ocean around Antarctica, they don’t alone explain why the polynyas form sometimes and not at other times.
Now Diana Francis of Khalifa University in Abu Dhabi, United Arab Emirates and her colleagues believe they have the answer. They combined satellite records and climate data and examined important polynical events in the Weddell Sea on the Antarctic coast in 1973 and 2017.
They found that flows of heat and water vapor in the sky, known as atmospheric rivers, traveled great distances, moving from the southeast coast of South America to the Weddell Sea in one case in 2017. In September of that year a river increased air temperatures in the Weddell Sea by 10 ° C.
It’s not just that the rivers of heat are starting to melt the ice pack, making it fragile and easily broken by cyclones. “The atmospheric rivers also intensify the storms because they deliver more water vapor. They are interconnected, not independent, ”says Francis.
The polynyas can provide benefits such as providing nutrients to marine life. However, like the melting of the Arctic sea ice, they are of global concern as they can accelerate climate change when dark open water reflects less solar energy back into space than white ice. Climate change, in turn, will affect future polynyas. Global warming is expected to increase the frequency of atmospheric river events by around 50 percent if carbon emissions remain high.
Journal reference: Science Advances, DOI: 10.1126 / sciadv.eabc2695
More on these topics: