The West Antarctic Ice Sheet is under pressure, with its break-up a matter of when, not if. Scientists now believe it will vanish “in our lifetimes”.
Last week, news emerged of the Antarctic largely maintaining the ice levels it sported some 100 years ago.
Through comparing the seafaring expedition logs of Robert Scott, Ernest Shackleton and Erich von Drygalski from 1897-17, researchers established a 14pc reduction in Antarctic summer sea ice since the early years of the 20th century.
Finding swells and reductions in sea ice throughout the century, it pointed towards a part of the planet more resilient than most when it comes to global warming.
The good news ends there, though.
Today, research into the West Antarctic Ice Sheet reveals worrying, visible problems.
One of the key glaciers in the region, the Pine Island Glacier, is breaking apart from the inside out, suggesting that the ocean is weakening ice on the edges of the continent.
And beyond the melting of the ice, this brings concerns for coastlines globally, for Pine Island is one of two glaciers that researchers believe are most likely to undergo rapid retreat, whereby melting would flood coastlines around the world.
“It’s generally accepted that it’s no longer a question of whether the West Antarctic Ice Sheet will melt, it’s a question of when,” said study leader Ian Howat, associate professor of earth sciences at Ohio State University.
“This kind of rifting behaviour provides another mechanism for rapid retreat of these glaciers, adding to the probability that we may see significant collapse of West Antarctica in our lifetimes.”
The bottom of the West Antarctic Ice Sheet lies lower than sea level, meaning ocean water can access areas far inland, unseen by scientists. This creates valleys of melting ice, putting pressure on the surface above.
The rift that shows these pressures was spotted by chance, when Howat and his team were analysing an image when the sun was low, causing a shadow behind the valley.
“The really troubling thing is that there are many of these valleys further up-glacier,” Howat added. “If they are actually sites of weakness that are prone to rifting, we could potentially see more accelerated ice loss in Antarctica.”
Studies have suggested that the West Antarctic Ice Sheet is particularly unstable, and could collapse within the next 100 years. The collapse, according to the team, would lead to a sea-level rise of almost three metres.