The East Antarctic Ice Sheet, this sleeping giant is waking up

Long considered not particularly vulnerable to global warming, the East Antarctic Ice Sheet is of increasing concern to scientists. In fact, if the losses and mass gains are currently more or less balanced, things may end up changing. This appears from a summary study published in the journal Nature 10 August.

We know that the West Antarctic Ice Sheet is particularly sensitive to variations in climate. In fact, unlike its eastern neighbor, it reaches a ceiling at relatively low altitudes and rests on a rocky bedrock largely below sea level. It is therefore at the forefront of impacts linked to warming the air and the climate. It is recalled that this huge piece of ice corresponds to about six meters of sea level rise.

For these reasons, scientists have been mainly interested in the instability of the West Antarctic Ice Sheet and relatively little in the East Antarctic Ice Sheet, which is considered to be much more stable. But from the top of its fifty meter equivalent in sea level, shows this eastern giant more vulnerable than long thought. A recent study revealed, for example, that during the interglacials 400,000 years ago, when the average temperature was only 1°C to 2°C warmer, the ice had retreated 700 kilometers in Wilkes Land.

The East Antarctic Ice Sheet, a long-term vulnerability

In a new study, researchers from the University of Durham (England) have shown that if greenhouse gas emissions continue at high levels, they will engage the East Antarctic Ice Sheet in a significant long-term decline. Specifically, the eastern ice sheet could add nearly half a meter to mean sea level by the end of the century, between one and three meters by 2300 and up to five meters by 2500.

Contribution of the East Antarctic Ice Sheet to mean sea level rise for 2100, 2300 and 2500 with limited (left column) or high (right column) CO2 emissions. Uncertainty is indicated by the different shades of blue. Credits: CR Stokes & al. 2022 / Richard Jones, Monash University.

Vise versaif warming is kept below 2°C, the contribution would remain marginal, with an increase of only two centimeters by 2100 and less than fifty centimeters by 2500. In either case, the projected mass loss during this century is heavily buffered by increased snowfall in the interior of the continentbecause a warmer atmosphere can hold more water and therefore produce more snow in a very cold climate.

A key conclusion of our analysis is that the fate of the East Antarctic Ice Sheet remains in our hands. says Chris R. Stokes, lead author of the study. ” This ice sheet is by far the largest on the planet, it contains the equivalent of 52 meters of sea level, it is really important not to wake this sleeping giant “.

Between past indices and future projections

To arrive at these results, the researchers used past and present observations as well as computer models to reassess the ice sheet’s response to different levels of warming corresponding to different levels of greenhouse gas emissions. The projections made up to 2500 were based, among other things, on the reaction of the ice sheet during the middle of the Pliocene three million years ago. With a climate 2°C to 4°C warmer than today, the eastern ice sheet had contributed several meters to sea level rise.

By limiting the global temperature rise to below the 2°C limit set by the Paris climate agreement, we should be able to avoid worst-case scenarios, or even halt the melting of the East Antarctic ice sheet. , and therefore limit its impact on global sea level rise says Chris R. Stokes.

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