Deep-Ocean Heat Threatens Antarctica Ice

A new decades-long study, led by the University of Cambridge with collaborators from the University of California, Scripps Institution of Oceanography, and University of California, Los Angeles, provides the first evidence that deep-ocean heat has moved closer to Antarctica. This warm mass, called 'circumpolar deep water,' has expanded and shifted toward the Antarctic continental shelf over the past 20 years, threatening the continent's fragile ice shelves. Joshua Lanham, the lead author, stated that this warm water can melt ice shelves from below, destabilizing them. These ice shelves are crucial for holding back Antarctica's inland ice sheets and glaciers, which contain enough freshwater to raise sea level by about 58 meters. Sarah Purkey noted that the ocean's circulation has changed, with the Southern Ocean absorbing over 90% of excess heat from global warming. Ali Mashayek highlighted that changes in the Southern Ocean's heat distribution have wider implications for the global climate system, including a potential weakening of the Atlantic meridional overturning circulation. This observed scenario was previously predicted by climate models but is now confirmed by data.