A robotic submarine has returned from exploring one of Antarctica’s largest glaciers. It came back with disturbing news – it could be melting faster than we previously thought.
Thwaites Glacier, a gigantic ice shelf in West Antarctica, has been on climate scientists’ radars for 20 years. But they were completely unaware of just how quickly the giant glacier is melting and how close it is to completely collapsing.
The first measurements ever performed in the dark waters under the 74,000 square mile (192,000 square kilometers) glacier revealed that a current of warm water is flowing from the east, chipping away at crucial “pinning points” that anchor the shelf to the land.
“Our observations show warm water impinging from all sides on pinning points critical to ice-shelf stability, a scenario that may lead to unpinning and retreat,” the study authors said in their paper which was published on April 9 in the journal Scientific Advances. This means that the entire ice-shelf could become detached and float into the ocean.
Also called the “Doomsday Glacier,” this giant chunk of ice has lost an estimated 595 billion tons (540 billion metric tons) of ice since the 1980s. This has contributed to a 4% rise in global sea levels since that time.
The glacier acts like a cork in a wine bottle – it stops the rest of the ice in that area from flowing into the ocea. So if Thwaites Glacier’s collapses, it could potentially take the rest of the West Antarctic Ice Sheet with it, causing a 10-foot (3 meter) rise in global sea levels.
“The worry is that this water is coming into direct contact with the underside of the ice shelf at the point where the ice tongue and shallow seafloor meet,” study co-author Alastair Graham and associate professor of geological oceanography at the University of South Florida said.
“This is the last stronghold for Thwaites and once it unpins from the sea bed at its very front, there is nothing else for the ice shelf to hold onto. That warm water is also likely mixing in and around the grounding line, deep into the cavity, and that means the glacier is also being attacked at its feet where it is resting on solid rock,” Graham continued.
The exact amount of melting isn’t clear, but the researchers predict that just one of the currents alone can reduce the ice at a rate of more than 85 gigatons per year.
Exposure to warmer water could also push Thwaites’ neighboring Pine Island Glacier past a tipping point. The Thwaites and Pine Island glaciers are currently responsible for 10% of the continuing rise in global sea levels.