For the first time, there is visible evidence showing that warm seawater is pumping underneath Antarctica's Thwaites Glacier—ominously nicknamed the Doomsday Glacier.
An international team of scientists—including a researcher from the University of Waterloo—observed it using satellite imagery and warns that it could accelerate catastrophic sea level rise in 10 to 20 years.
The intrusion of seawater causes the ice to continuously lift off the land and settle back down again. Ice melts intensely when it first touches seawater, and because Thwaites Glacier measures about 120 kilometres wide by 1.2 kilometres deep, this effect could lead to devastating sea level rise. The glacier is situated in a basin. To date, the ocean water has only touched the rim of it. But the researchers predict it may only take 10 to 20 years before the glacier retreats into the deeper part of the basin, at which point glacier melt will likely speed up even more.
"Thwaites is the most unstable place in the Antarctic and contains the equivalent of 60 centimetres of sea level rise," said Dr. Christine Dow, a professor in the Faculty of Environment at the University of Waterloo, and a co-author of the study. "The worry is that we are underestimating the speed that the glacier is changing, which would be devastating for coastal communities around the world."
The world has already felt the social and economic consequences from a couple of centimetres of sea level rise. However, the researchers note that the sea level rise of an additional half-metre or more will gravely impact populations in many low-lying areas like Vancouver, Florida, Bangladesh and low-lying Pacific islands, such as Tuvalu and the Marshall Islands.
The researchers used ICEYE DInSAR satellite data and subglacial water modelling to detect the seawater intrusion and its impacts. Dow and her team at Waterloo are currently working on creating new models that consider the impact of ocean water flowing into the basin and subglacial water flowing out and mixing with ocean water to accurately predict how fast the glacier will melt.
"At the moment we don't have enough information to say one way or the other how much time there is before the ocean water intrusion is irreversible," said Dow, who is also the Canada Research Chair in Glacier Hydrology and Ice Dynamics. "By improving the models and focusing our research on these critical glaciers, we will try to get sea level rise estimates at least pinned down for decades versus centuries. This work will help people adapt to changing ocean levels along with focusing on reducing carbon emissions to prevent the worst-case scenario."
Dr. Eric Rignot, lead author and professor of Earth system science at the University of California, Irvine (UC Irvine) hopes these results will lead to increased support for research examining the changes taking place beneath glaciers in Antarctica.
"There is a lot of enthusiasm from the scientific community to go to these remote, polar regions to gather data and build our understanding of what's happening, but the funding is lagging," said Rignot, who is also affiliated with the Jet Propulsion Laboratory at the California Institute of Technology. "We operate at the same budget in 2024 in real dollars that we were in the 1990s. We need to grow the community of glaciologists and physical oceanographers to address these observation issues sooner rather than later, but right now we're trying to climb Everest in tennis shoes."
Dow and Rignot collaborated with researchers at UC Irvine and ICEYE. The study, Widespread seawater intrusions beneath the grounded ice of Thwaites Glacier, West Antarctica, appears in Proceedings of the National Academy of Sciences (PNAS).
