Crevices and weak points in the Antarctic glacier are melting more rapidly than other areas of the ice, two papers published in Nature Journal found.
The underside of the Thwaites Glacier was mapped out for the first time by a remotely operated vehicle called ‘IceFin’ in two studies that uncovered the true extent of glacial melting and sparked fears about sea-level rise.
The melting, caused by rising sea temperatures, is happening at a slower rate than was previously predicted by computer models, scientists found.
However, the papers also revealed that warm water penetrating into crevices and weak points in the ice is causing rapid melting and glacier retreat along the ‘grounding line’ — where the glacier’s floating ice shelf attaches to its grounded base.
“Our results are a surprise but the glacier is still in trouble,” said Dr Peter Davis, a lead author of one of the studies. “What we have found is that despite small amounts of melting there is still rapid glacier retreat, so it seems that it doesn’t take a lot to push the glacier out of balance.”
“A global rise of only 45cm could result in areas like the Maldives losing over 75% of their landmass”
An out of balance glacier could have a significant impact on global sea-level even while melting is relatively slow, scientists now worry.
Speaking to The Climate, Keith Nicholls, one of the lead principal investigators, explained: “The concern is that as the grounding line retreats, the glacier flows faster, depositing more ice into the ocean and raising sea level.”
The Thwaites Glacier is nicknamed the ‘Doomsday Glacier’ because its ice mass stores the equivalent of over 60cm in global sea-level rises. Because of its prominent position and volatility, there are also fears that its collapse could set off a chain reaction in neighbouring glaciers, triggering an additional 3m of sea-level rise.
A global rise of only 45cm could result in areas like the Maldives losing over 75 percent of their landmass, islands in the Pacific becoming fully submerged, and countries like China and Bangladesh suffering land losses in densely populated urban regions.
Thwaites has therefore long been a focus for researchers, but this is the first time that a large-scale survey of the state of the glacier has been conducted.
“Warm water is getting into the cracks, helping wear down the glacier at its weakest points”
The study involved sending the 11-foot tube-shaped IceFin across the underside of the floating ice shelf carrying various temperature measuring devices, saline testers to check saltwater concentrations and imaging hardware.
Dr Britney Schmidt, another lead author, explained that “These new ways of observing the glacier allow us to understand that it’s not just how much melting is happening, but how and where it is happening that matters in these very warm parts of Antarctica.”
“We see crevasses, and probably terraces, across warming glaciers like Thwaites. Warm water is getting into the cracks, helping wear down the glacier at its weakest points.”
Asked whether there was any hope left to stop or slow the collapse of the ‘Doomsday Glacier’, Nicholls replied:
“The only thing that might change the retreat rate and which we have any sort of control over, are the local oceanographic conditions. Various (very expensive) engineering solutions to effect those changes have been suggested, but a change in the root cause — thought to be human-induced climate change combined with strong, natural, interannual variability — remains the preferred option.”
“Without further research we cannot say whether changing those oceanographic conditions can halt the retreat, or whether a ‘tipping point’ has already been crossed. Further research will reduce the uncertainty about Thwaites Glacier’s future contribution to sea level and aid planning by policymakers.”