West Antarctica Glaciers: Past the Point of No Return

We passed the point of no return and at this point, let's say it's just a matter of time before these glaciers completely disappear to sea.

We've focused more on this particular sector of West Antarctica because this is where we see the most dynamic changes.

We've been observing changes in speed, acceleration of these glaciers, thinning of these glaciers and also their retreat inland, which is kind of a feedback that will maintain that retreat and that thinning and that acceleration for many years to come.

We've been looking at 40 years of changes in velocity over that whole sector. And what we see is a continuous increase in discharge of ice from the glacier to the ocean.

In most cases when you look at ice sheets the most important stuff is taking place at the bottom that you can't see.

So the grounding line is the place where the glacier detaches from the bed and becomes afloat with the ocean. And as it becomes afloat in the ocean, we see the retreat of the grounding line on the glacier as its being melted more strongly by the ocean. And you see that the bed of the glacier slopes inland. It never gets away from the water. The water keeps following the glacier because it gets deeper inland.

The first time we could image it was in 1992 and in 2011 we looked at the data we went, " Wow!"

There's been so much change in the position of this grounding line. You can't miss it.

So there are a bunch of feedbacks that make this retreat unstoppable unless suddenly the glacier starts retreating in a bed that rises up.

But we don't see that in any of these glaciers.

This system is evolving very fast and is progressing exactly as what you would expect if it was about to collapse to sea.

They're retreating at rates about a kilometer per year

If these glaciers were sustaining this rate of retreat, they would disappear completely in a couple of centuries.