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