New Delhi: Antarctica’s “Doomsday Glacier” could add up to 3 cm to global sea levels by 2100, twice as much as earlier estimates suggested, according to a new study. The findings point to a key process beneath the glacier that many earlier climate scientists had missed.
The Thwaites Glacier, in West Antarctica, was nicknamed the ‘Doomsday Glacier’ because its collapse could raise sea levels and put coastal communities at greater risk of flooding. A recent study, published in Nature Communications on 12 October, suggests that the glacier could lead to a significant rise in sea levels even without further global warming.
The study, led by scientists from the University of California, Irvine, and NASA’s Jet Propulsion Laboratory, found that warm seawater is reaching beneath the ice in ways that many earlier climate models did not account for.
“Glaciologists have long based their assumptions of ice sheet dynamics on the ‘grounding line,’ a discreet, narrow and mostly stable demarcation where ice leaves the land and begins floating on water. We have come to acknowledge a different arrangement beneath Earth’s major ocean-terminating glaciers. Satellite observations demonstrate the existence of a ‘grounding zone,’ sometimes kilometers wide, where warm ocean water is reaching deep underneath the ice sheets and causing vigorous melting,” lead author Mattia Poinelli said in a statement.
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A hidden factor
The team built a computer model that accounts for this “grounding zone” and tested it against satellite observations of the glacier’s retreat, thinning and faster movement over nearly three decades. The new model better matched the changes seen in the real world and produced higher estimates of sea-level rise in the future.
“Most projections up-to-present have struggled to match the rapidity of the mass loss because of missing physics; our new model with more complete physics is able to match the record and then produces projections that are twice larger than before. These results predict greater risk of and exposure for coastal flooding than anticipated in the coming decades,” co-author Eric Rignot, UC Irvine professor of Earth system science, said in a statement.
The researchers also found a 60 per cent chance that the glacier could detach from the Mouginot Ridge, an underwater rise that currently helps hold back its flow, by the end of the century. If this happens, the glacier could retreat towards the next major ridge, speeding up ice loss.
Thwaites already contributes to global sea-level rise, and its retreat has worried scientists for decades. The new findings suggest that overlooking what happens beneath the ice may have led scientists to underestimate the risks that the glacier poses to coastal areas.