More and deeper than expected channels could speed the glacier’s melting from below

New maps show how warm water may reach Thwaites Glacier’s icy underbelly

New seafloor maps reveal the first clear view of a system of channels that may be helping to hasten the demise of West Antarctica’s vulnerable Thwaites Glacier. The channels are deeper and more complex than previously thought, and may be funneling warm ocean water all the way to the underside of the glacier, melting it from below, the researchers found.

Scientists estimate that meltwater from Florida-sized Thwaites Glacier is currently responsible for about 4 percent of global sea level rise (SN: 1/7/20). A complete collapse of the glacier, which some researchers estimate could happen within the next few decades, could increase sea levels by about 65 centimeters. How and when that collapse might occur is the subject of a five-year international collaborative research effort.

Glaciers like Thwaites are held back from sliding seaward both by buttressing ice shelves — tongues of floating ice that jut out into the sea — and by the shape of the seafloor itself, which can help pin the glacier’s ice in place (SN: 4/3/18). But in two new studies, published online September 9 in The Cryosphere, the researchers show how the relatively warm ocean waters may have a pathway straight to the glacier’s underbelly.

New maps show how warm water may reach Thwaites Glacier’s icy underbelly

From January to March 2019 researchers used a variety of airborne and ship-based methods — including radar, sonar and gravity measurements — to examine the seafloor around the glacier and two neighboring ice shelves. From those data, the team was able to estimate how the seafloor is shaped beneath the ice itself.

These efforts revealed a rugged series of high ridges and deep troughs on the seafloor, varying between about 250 meters and 1,000 meters deep. In particular, one major channel, more than 800 meters deep, could be funneling warm water all the way from Pine Island Bay to the submerged edge of the glacier, the team found.