Rising Temperatures Strengthen Ocean Currents and Threaten Ice Shelves in West Antarctica

The Cryosphere, September 1

Rising global temperatures are accelerating melt at the base of ice shelves in West Antarctica, sending large quantities of freshwater into the surrounding ocean (although not raising sea levels, since ice shelves already rest on water). This influx of freshwater creates a buoyant upper layer of water that compresses the deeper layers of warmer, saltier water. The increasing depth of these lower layers strengthens the flow of the Antarctic Coastal Current (AACC), allowing it to transport more water, and at a faster rate. This Antarctic meltwater becomes trapped in two troughs at the bottom of the sea, and presses warmer water upward against the ice shelves of West Antarctica. These ice shelves have stabilized the West Antarctic Ice Sheet (WAIS) for many millennia. Changes in the salinity, temperature, and layering of these surrounding waters due to a rapidly warming climate make the ice shelves increasingly vulnerable to destabilization, which could result in the unexpectedly rapid disintegration of the West Antarctic Ice Sheet. The recently released IPCC WGI AR6 report noted that such potential disintegration, together with other sources means that up to 5 meters sea-level rise already by 2150 cannot be ruled out.