A confluence of hot water threatens to overthrow the pillars that keep the Doomsday Glacier going.
The first measurements ever made under the icy tongue of the Thwaites Glacier of Antarctica now showed a previously underestimated stream of warm water from the east.
This inflow of heat mixes with other waters under the glacier and finds several critical ‘fixed points’, say researchers.
If the activity continues or, worse, accelerates, the team is concerned that it could eventually release the large amounts of land-borne ice that flows into Pine Island Bay from the seabed.
The Thwaites Glacier got the nickname Doomsday Glacier because it is so large – at 192,000 square kilometers (74,000 square miles), which is slightly smaller than the state of Kansas in the US – and melts at an alarming rate. As a result, the future of the West Antarctic ice sheet remains the biggest single point of uncertainty for sea level rise.
Due to the remote location of the glacier and the dangerous conditions in the region, only a few measurements have been taken near the edge of the ice shelf, and so far no one has been taken in the cavity below.
“The good news is that we are now, for the first time, collecting data needed to model the dynamics of Thwaite’s glacier,” said physical oceanographer Anna Wåhlin of the University of Gothenburg in Sweden.
“These data will help us better calculate ice melting in the future. Using new technology, we can improve the models and reduce the great uncertainty that currently prevails over global sea level variations.”
The information was collected by an underwater vehicle called Ran, which swam deep under the thick ice to measure the strength, temperature, salinity and oxygen content of the underlying ocean currents.
The trip was more successful than scientists had hoped, but the results were not as promising.
At present, the Thwaites Glacier makes up about 10 percent of the current sea level rise, but because hot and salty waters tend to converge below it, the ice shelf holds the potential to contribute much, much more as the planet warms. Like taking a cork out of a wine bottle, the loss of this ice shelf can cause even more ice to melt on land and flow into the sea.
Eventually, three inflows of hot water were identified by researchers, one of which we seriously underestimated. Deep water flow from the east is suspected to be blocked by an underwater reef nearby, but Ran’s new data suggests that these deep currents are still finding the bay.
“The channels for hot water to access and attack Thwaites were not yet known to us,” said geologist Oceanographer Alastair Graham of the University of South Florida.
“Using sonar on the ship, nestled with a very high resolution mapping of Ran, we were able to notice that there are different paths that take water in and out of the ice shelf cavity, influenced by the geometry of the ocean floor.”
Ultimately, this means that hot, salt water enters the cavity beneath the Thwaites ice sheet from both sides of the main anchorage point in the north, potentially destabilizing the entire structure.
It is still unclear how much of the available heat contributes to melting this main point, but the authors predict that the energy transported by only one local stream is sufficient to supply the above ice with more than 86,000 kilograms (about 95 tons). melt. per year.
This is equivalent to the total basal melt of the entire Thwaites ice shelf between 2010 and 2018, indicating that this hot inflow is likely to affect the entire system’s melting pattern.
“This bottleneck is one of the last supporting features limiting the flow of ice from upstream, and satellite observations indicate that its extent has declined over the past few decades,” the authors write.
The world’s day of doom may come sooner than we thought.
The study was published in Scientific progress.