Scientists Detect Warm Deep Water Shift to Antarctic Shelves

Scientists have detected for the first time the expansion and poleward shift of warm circumpolar deep water toward Antarctica's ice shelves, providing evidence that ocean heat is melting the continent's ice from below and potentially accelerating sea level rise.

The study, led by Joshua Lanham of the University of Cambridge's Department of Earth Sciences in collaboration with researchers from the University of California, analyzed four decades of oceanographic data from the Southern Ocean. Published in Communications Earth and Environment, the research combined infrequent ship-based measurements, taken roughly once per decade, with continuous data from the Argo array of autonomous floats. Using machine learning, the team created detailed monthly profiles of temperature and salinity, revealing that the circumpolar deep water, a relatively warm and salty mass typically found around 1,600 feet below the surface, has thickened and moved onto the Antarctic continental shelf over the past 20 years.

This water, at about 2 degrees Celsius, flows beneath floating ice shelves, causing basal melting and thinning. Ice shelves buttress inland glaciers and ice sheets, which hold enough...