Disappearance of West Antarctic glaciers could raise sea level by 4.2 meters

Climatologists have calculated in detail the consequences of the complete disappearance of glaciers in western Antarctica and have concluded that their disappearance will raise sea levels by 4.2 meters. This is about a meter higher than previous estimates. The results of their study were published by the scientific journal Science Advances.

“The disappearance of the West Antarctic ice sheet is traditionally thought to raise sea level by 3.2 meters. Previous attempts to calculate the consequences of this cataclysm did not take into account how it would be affected by geological processes associated with the disappearance of the heavy ice cap. We found that they would add about a meter more to the overall rise in sea level,” said Evelyn Powell, one of the authors of the paper, a researcher at Harvard University.

Climatologists believe that the first and main victims of global warming will be the polar regions of the Earth and the mountain glaciers. Temperatures there are already 4-9 ° C higher than in past centuries. As a result, their area may greatly shrink, and most of the Antarctic and Arctic in the next centuries – be free of ice.

These processes have already begun to affect the glaciers in western Antarctica. This is particularly true of the ice masses that cover the Antarctic Peninsula. For example, three years ago one of the last shards of the Larsen Glacier located on its territory collapsed. This resulted in an iceberg weighing a trillion tons, comparable in area to Estonia or the Moscow region.

Because of this, scientists fear that a significant part of the glaciers of West Antarctica will disappear by the end of this century. If they disappear completely, sea level may rise by about three meters. As a result, many coastal areas on other continents could be submerged.

Harvard climate scientists were interested in the longer-term consequences of this glacial retreat, which can be observed in many regions of North America and Eurasia that were covered by a multi-kilometer ice cap in the recent past.

This ice crust pressed the crustal and mantle rocks beneath it, forcing the latter to deflect and flow away from the ice cap. As a result, the crustal rocks on the edge between the glacier and the area free of it began to bulge upward, and structures that geologists call “edge domes” emerged.

When the glacier disappeared and the pressure on the mantle eased, the rocks of the domes began to sink gradually. Therefore, the Netherlands and many other coastal regions of the Earth are now gradually “sinking”, despite the fact that the sea level is almost unchanged. Residents of Washington and other coastal cities in the U.S. have recently encountered this problem.

Harvard climatologists were interested in how such processes will affect sea level rise after the collapse of the glaciers of West Antarctica. It is traditionally thought that their contribution to this process will be vanishingly small, but Powell and her colleagues pointed out that the appearance of marginal domes will affect not only the height of the Antarctic coast, but also how meltwater will actively accumulate in the lowlands on the continent.

Much to the surprise of climate scientists, their calculations showed that the “surfacing” of mantle rocks and Antarctic crust will greatly accelerate the escape of meltwater into the oceans, resulting in an increase in its level by about 20% this century alone, and by a third by the end of this millennium. As a result, the sea level will rise by an additional meter, which will negatively affect life and the economy of many coastal cities.

As scientists suggest, similar, though less pronounced processes will occur in many regions of East Antarctica, when its ice begins to melt and destabilize. Their existence should be taken into account when making predictions of how sea levels will rise in the coming centuries and millennia, summarized the climatologists.

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