L’inlandsis de l’Antarctique de l’Est, ce géant endormi sur le point de se réveiller

L'inlandsis de l'Antarctique de l'Est, ce géant endormi sur le point de se réveiller

Long considered not very vulnerable to global warming, the East Antarctic Ice Sheet is of growing concern to scientists. Indeed, if for the moment the losses and gains in mass are more or less balanced, things could end up changing. Evidenced by a summary study published in the journal Nature August 10

We know that the West Antarctic Ice Sheet is particularly sensitive to climatic variations. In fact, unlike its eastern neighbor, it peaks at relatively low altitudes and rests on a rocky base largely below sea level, thus being at the forefront of air-warming influences. And the water. It is recalled that this immense piece of ice is equivalent to about six meters of rise in sea level.

For these reasons, scientists have been primarily interested in instabilities in the West Antarctic Ice Sheet and relatively little in those in the East Antarctic Ice Sheet, which is considered much more stable. However, from the top of its fifty meters equivalent to sea level, this eastern giant shows more vulnerable than previously thought. A recent study revealed, for example, that during the interglacial 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 at the University of Durham (England) have shown that if greenhouse gas emissions continue at high levels, they would compromise the East Antarctic Ice Sheet in significant long-term contraction. Specifically, the eastern ice sheet could add almost 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 et al. 2022 / Richard Jones, Monash University.

On the contraryif warming remains 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 both cases, the expected mass loss during this century is strongly buffered by increased snowfall in the interior of the continentbecause a warmer atmosphere can hold more water and thus produce more snow in very cold weather.

A key takeaway from 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, containing the equivalent of 52 meters above sea level. It is very important not to wake up this sleeping giant. “.

Between past indices and future projections

To arrive at these results, the scientists took advantage of past and present observations as well as computer models to reassess the response of the ice sheet to different levels of warming corresponding to different levels of greenhouse gas emissions. Projections made up to 2500 were based, among other things, on the response of the polar cap during the mid-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 global temperature rise below the 2°C limit set by the Paris climate agreement, we should be able to avoid worst-case scenarios, or even stop the melting of the East Antarctic Ice Sheet, and thus limit their impact on the world. Rising sea levels says Chris R. Stokes.


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