Overview

• Since 2015, surface salinity south of 50° latitude has reversed decades of freshening, coinciding with a loss of Antarctic sea ice equivalent to Greenland’s area
• Saltier surface water is weakening stratification and allowing deep ocean heat to rise and melt sea ice from below in a self-reinforcing cycle
• Record-low ice summers have reopened the Maud Rise polynya in the Weddell Sea and led to more than twice as many icebergs calving from the Antarctic margin
• Years with extremely low sea ice have warmed the Southern Ocean by about 0.3°C and kept temperatures elevated for at least three subsequent years
• Civilian access to Special Sensor Microwave Imager/Sounder data will end on July 31, jeopardizing the continuity of long-term Antarctic sea ice observations