The Weddell Polynya

source NASA

A recent major climatic event was the occurrence of a very large region, 350,000 km2, of open water or polynya
within the ice-covered Weddell Sea during the austral winters of 1974-76. There was vigourous air-sea interaction
within the polynya that resulted in the convective overturning of the water column and the formation of vast amounts
of cold and very dense Antarctic Bottom Water that has since flowed equatorward cooling the abyssal waters of
the South Atlantic Ocean.