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Thwaites Glacier, aka the ‘Doomsday Glacier’, will keep melting even if our turbocharged oceans cool down, scientists have warned.
The world’s oceans reached their highest daily temperature on record this summer, with sea surfaces outside the polar regions averaging 21.1°C on 22 August. With El Niño still intensifying in the Pacific, it is unlikely temperatures will drop dramatically in the near future.
But even under the “most extreme ocean cooling conditions imagined”, new research led by British Antarctic Survey (BAS) has found that the Doomsday Glacier, located in West Antarctica, will continue losing ice for at least the next 150 years.
The total collapse of the ice sheet would contribute an estimated 65cm to global sea level rise. To put that into perspective, for every centimetre of sea level rise around an additional six million people on the planet are exposed to coastal flooding.
‘Unavoidable future ice loss’ for Doomsday Glacier
Researchers ran a modelling experiment for Thwaites Glacier and its neighbour Pine Island Glacier, which are currently the largest contributors to ice loss from this area of Antarctica.
They completely switched off the melting effects of the ocean – driven by climate change – beneath both glaciers in three independent computer models.
Published in the science journal Geophysical Research Letters, the study revealed a “striking difference” between how the two glaciers fared over a 150-year period.
Pine Island Glacier responded as scientists might have expected. Under the modelling, the ice sheet stopped melting and began thickening – advancing back towards the position it held in the first half of the 20th century.
However, Thwaites Glacier continued to lose ice, even without any ocean melting. The rate of ice loss slowed down over time as the glacier thinned.
“These results show that past changes in ocean-driven melting have now committed us to unavoidable future ice loss from Thwaites Glacier,” says Dr Rosie Williams, a glaciologist at BAS and lead author of the paper.
“This ice loss cannot be undone or prevented by simply cooling the ocean.”
Can we stop the Doomsday Glacier melting?
A zero-melting scenario would never occur in the real world, as the presence of seawater below glacier ice alone is enough to cause some level of melting.
BAS ocean modeller and co-author of the report Professor Paul Holland explains that the Thwaites Glacier started to retreat in the 1940s, with the warming of our oceans becoming a “major factor” driving ice loss.
While the simulations show that historical melting of Thwaites Glacier has “committed future generations to the challenges of sea level rise”, the ice loss will be further exacerbated if the world does not reduce and ideally reverse the emissions of greenhouse gases.
“We don’t yet know if Antarctica’s other major glaciers are moving into a state of committed change,” Holland says.
“We urgently need to take action to modify the human activities that are driving changes in ocean melting of these glaciers.”