Cause and Effect | The retreating of Antarctica's glaciers
The Antarctic Ice Sheet has long been a key indicator of the climate crisis and a driver of sea-level rise. Here is what new research on the glaciers melting tells us:
Visuals of ice shelves breaking off to form smaller icebergs, polar bears balancing atop thin sheets of ice, and huge chunks of ice falling into the ocean often are among those most often used to evoke the intense worry global warming deserves.
But used and reused ad nauseum over decades, these visuals have led to a great deal of desensitising that makes many think the climate crisis is far removed from their daily lives.
But is it really as far and distant into the future as it appears?
New research suggests not.
Until recently, it was believed that east Antarctica would not experience the same level of ice loss that is occurring in the West, where, scientists say, the massive Thwaites Glacier could cross a tipping point in the next three to 10 years.
The Thwaites Glacier is notable because it spreads over a size equivalent to Great Britain.
But this isn't all that's melting: Warm water may now be reaching previously elusive parts of Antarctica, which — with its perennial ice cover — acts not only as an important temperature regulator for the planet, but where melting could add enough water to the world’s oceans and seas that coastal cities and low-lying islands could be drowned.
A study, Vulnerability of Denman Glacier to Ocean Heat Flux Revealed by Profiling Float Observations, published in Geophysical Research Letters in September last year, concluded that east Antarctica’s Denman Glacier, sitting atop the deepest land canyon on Earth, is on the path of “unstable retreat”.
It is melting at a rate of 70.8 billion tonnes a year.
Thwaites holds enough water to raise the sea level by over 0.5m. Denman, by comparison, has a volume of ice equivalent to a 1.5 m sea level rise.
A bit of perspective: The Intergovernmental Panel on Climate Change 2022 report on impacts and adaptation said that the population at risk of a 100-year coastal flood increases by nearly 20% if the global mean sea level rises by 0.15m without adaptation. This at-risk population doubles at a rise of 0.75m in mean sea level and triples at 1.4m.
A March 2020 study, Grounding Line Retreat of Denman Glacier, East Antarctica, published in Geophysical Research Letters, found that Denman lost more than 268 billion tonnes of ice between 1996 and 2018.
"The ice in West Antarctica has been melting faster in recent years, but the sheer size of Denman Glacier means that its potential impact on long-term sea level rise is just as significant," study co-author Eric Rignot, a professor of Earth system science at the University of California, Irvine, said in a statement issued at the time.
The Antarctic Ice Sheet has long been a key indicator of the climate crisis and a driver of sea-level rise.
Between 1979 and 2017, it added 13.8 millimetres to sea level rise, a paper, Four decades of Antarctic Ice Sheet mass balance from 1979–2017, published in the Proceedings of the National Academy of Sciences said in 2019.
"The more we look at this system the more we realise this is a fragile system," Rignot then told Science. "Once these glaciers are destabilised there is no red button to press to stop it."
The melting is likely to get worse as the planet warms, intensifying the temperature difference between Antarctica and the rest of the world, thus creating stronger polar winds that bring warm water beneath East Antarctica.