'Atmospheric rivers' helped open a Portugal-sized hole in Antarctica's winter sea ice

Polynyas are patches of open water surrounded by sea ice, where heat and moisture can pass freely between the ocean and atmosphere. In August 2024, a vast polynya opened up in Breid Bay, off the coast of East Antarctica, in the depths of winter. The region had stayed ice-covered at this time of year ever since satellite records began in 1979.

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