Antarctica’s ‘doomsday’ glacier is heading for catastrophic collapse

A six-year investigation into the vast Thwaites glacier in Antarctica has concluded with a grim outlook on its future.

Often dubbed the “doomsday glacier”, this huge mass of ice is comparable in size to Britain or Florida and its collapse alone would raise sea levels by 65 centimetres. Worse still, this is expected to trigger a more widespread loss of the ice sheet covering West Antarctica, causing a calamitous sea level rise of 3.3 metres and threatening cities like New York, Kolkata and Shanghai.

It is an extremely remote and difficult area to get to, but the International Thwaites Glacier Collaboration (ITGC), a joint UK-US research programme, has managed to deploy 100 scientists there over the past six years, using planes, ships and underwater robots to study the dynamics of this ice in detail.  “It was a tremendous challenge, and yet we really learned a lot,” says Ted Scambos at University of Colorado Boulder.

These discoveries include the fact that Thwaites glacier is particularly vulnerable, as it rests on a bed of rock that is well below sea level, and is being melted from the underside by warmer seawater. What’s more, the bedrock slopes downwards towards the interior of the ice sheet, so, as the glacier retreats, even more ice is exposed to warm seawater, threatening to accelerate the collapse.

“The bed gets deeper and deeper,” says Mathieu Morlighem at Dartmouth College in Hanover, New Hampshire, a member of the ITGC team. “We know that’s unstable.” He and his colleagues used computer models to predict the future state of the glacier under different levels of carbon dioxide in the atmosphere, finding that “for almost any carbon emission scenarios, we run into this instability” and the glacier front retreats inland. The key question is how quickly this might happen.

“It’s not going to instantaneously lead to a catastrophic retreat in the next year or the year after, but, at the same time, we are very sure that Thwaites is going to continue to retreat, and ultimately the retreat is going to accelerate,” says Rob Larter at the British Antarctic Survey, another member of the team. “We can’t put an exact time frame on that.”

Ultimately, however, the ITCG researchers think that, by the end of the 23^rd century, Thwaites glacier and much of the West Antarctic ice sheet might be lost.

The slightly better news is that we still have time to influence how rapidly this process occurs, by making drastic efforts to reduce carbon emissions. “We can buy us time,” says Morlighem. “We still have control on how quickly Thwaites loses mass.”