The apocalypse glacier is cracking

With Mathilde Fontez, editor-in-chief of the scientific magazine Epsiloon, today we are looking at the glacier of the apocalypse, the Thwaites glacier. In recent days, we have been taking stock: 2021 is in the top 5 of the hottest years. And it is not without consequences.

franceinfo: We are measuring more and more cracks in Antarctic glaciers, in particular one of them…

Mathilde Fontez: This glacier has been closely monitored by specialists for years. It is the Thwaites glacier, and it even is nicknamed “the glacier of the apocalypse”. Because it’s the biggest: it covers about a third of the surface of France.

And because it has a strategic position: it is located west of Antarctica, at the entrance to a series of valleys that are below sea level. It therefore plays the role of a sort of ice plug: if it gives way, everything risks melting behind it.

But we observe signs of weakness of this glacier?

Yes. Glaciologists sounded the alarm a few weeks ago when they met in New Orleans. New cracks have been detected by satellite observation campaigns.

These cracks progress at speeds that can reach 2 kilometers per year, which is a lot. And there is one that extends to the middle of the glacier. Not to mention that other measurements, taken by a diving robot, show that the ice is hollowing out under the glacier. It melts from below.

Does the water seep under the glacier?

More and more, yes. So we have to remember what a glacier is: it’s a river of ice that normally flows very slowly. And that glacier, it throws itself into the sea.

At the front, there is therefore a platform which floats on the water and which gradually unhooks. At the back, normally, the glacier is retained because it rests on the rock. And this is where the researchers see the water creeping in: the Thwaites glacier is breaking away from the rock.

A kind of vicious circle has taken place: the hollows in the rock create turbulence, which attracts warmer water. Measurements of the water temperature below the glacier show it to be 1 or 2 degrees above freezing point. This accelerates the melting.

Can we predict what will happen?

Researchers are doing numerical simulations to try to predict crack progression, yes. But it is not an exact science, in particular because of these vicious circles, these phenomena which self-amplify and which make the melting of the glacier not linear. It will melt, that’s for sure. There is no doubt. The question is: when?

There, the researchers announced that it is likely to break in the next 5 years. This could increase its contribution to global sea level rise. It is now responsible for 4%. It could go up to 25%. Knowing that a collapse of the entire glacier would raise global sea level by 65 centimeters. And that ultimately, if all the surrounding valleys melt, an elevation of 3 meters is predicted. It would be a global upheaval.