Atmospheric rivers help create massive holes in sea ice

Atmospheric rivers help to create enormous sea ice holes that have been spotted in the Antarctic region, according to a study from Rutgers University. The researchers believe that these long rivers of warm air may also be influencing the ocean conditions around the continent and contributing to climate change.

Extremely long plumes of warm air that carry water vapor from the tropics are known as atmospheric rivers. The research team set out to investigate the role of atmospheric rivers in the emergence of massive holes in sea ice called polynyas.

The study was focused on the Weddell Sea region of the Southern Ocean near Antarctica, where polynyas have been known to occur. A large hole opened up in this area that was first observed in 1973, followed by another hole that developed in the early spring of 2017.

The researchers determined that repetitive, intense atmospheric rivers during late August through mid-September 2017 played a crucial role in forming the sea ice hole. The rivers carried in warm, moist air from the coast of South America, heating up the surface of the sea ice enough to make it vulnerable to melting.

“Polynyas strongly influence the physical and ecological dynamics of the Southern Ocean,” said study co-author Kyle Mattingly. “They serve as giant ‘windows’ in the sea ice that allow large amounts of heat to move from the ocean to the atmosphere, modifying regional and global ocean circulation. They also affect the timing and magnitude of phytoplankton (algae) blooms, which are the base of the marine food web. Our study will pave the way for greater understanding of climate variability and climate change in these regions.”

While previous studies have revealed that atmospheric rivers influence melting of West Antarctic land ice and ice shelves, the new study is the first to confirm the effects on Antarctic sea ice.

The atmospheric rivers are thousands of miles long, and the polynyas cover thousands of square miles.

In the coming decades, atmospheric rivers are predicted to become more frequent, longer, and wider. They will become even more effective in transporting water vapor to the Antarctic region, where precipitation will be intensified.

Atmospheric rivers are also expected to make landfall closer to the poles, and further research is needed to predict how the compounding impacts of climate change will affect the frequency and potential consequences of large sea ice holes. 

The study is published in the journal Science Advances.

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By Chrissy Sexton, Earth.com Staff Writer