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Sea level rise from Antarctic melt could be 30% higher than we thought

The Antarctic ice sheet contains a global disaster that is waiting to happen.

As global temperatures continue to rise due to anthropogenic climate degradation, water currently locked in the form of Antarctic ice will melt in the oceans, raising sea levels to a point that will have a significant impact on coastal communities, even over the next few years. decades.

Over the next 1,000 years, our best forecasts show that this height is 3.2 meters (10.5 feet), but new research shows that even this alarming figure may be a little too optimistic. According to the revised forecast, the growth over the next millennium could be even a meter higher, which will lead to an additional 30% increase.

This is a result that will have serious implications for the way we model the effects of climate degradation in the future.

“Any published forecast of sea level rise due to the melting of the Antarctic ice sheet, which is based on climate modeling, whether the forecast extends to the end of this century or longer in the future, will have to be revised upwards, because of their work, “said Earth and Planetary scientist Jerry Mitrovica of Harvard University.



It’s all about something called a water discharge mechanism. As the ice sheet melts, the Antarctic rock, which is currently below sea level, will rise, throwing the melted water around it into the ocean. This is the additional, discharged water that will be responsible for the additional meter, according to the new calculations.

“The scale of the effect shocks us,” said Earth and planet scientist Linda Pan of Harvard University. “Previous studies that have looked at the mechanism have dismissed it as insignificant.”

Pan, her colleague Evelyn Powell and their team first noticed the effect when they worked on a different project to change the sea level. As they did their calculations, they noticed that there was more growth in the water discharge mechanism than they expected, so they changed their focus to find out what was going on.

According to a number of studies, the mantle under the ice sheet of West Antarctica is shallow and of low viscosity. This means that it must bounce up quickly, repelling the molten water. This has been known for some time, but the contribution to sea level rise has been assessed as minimal.

However, the team’s calculations added to the complex, three-dimensional viscoelastic structure of the mantle and used it to model both past and future sea level changes due to the melting of the Antarctic ice sheet.

During the last interglacial period, when the contribution to sea level rise from the collapse of the Antarctic ice sheet was estimated at about 3 to 4 meters, the team found that the water ejection mechanism had added a meter over 1,000 years.

“No matter what scenario we used to collapse the Western Antarctic ice sheet, we always found that this extra meter of global sea level rise had happened,” Pan said.

When modeling a future collapse, they find a similar contribution. But this is not a problem, we can just kick along the way. The team’s calculations suggest that when we add the expulsion mechanism, we can see an 18% increase in the projected sea level rise by the end of this century.

This finding strongly emphasizes the need for urgent action to achieve the carbon neutrality goals set out in the Paris Agreement before we cross the point of no return.

“Sea level rise doesn’t stop when the ice stops melting,” Pan said. “The damage we are doing to our shores will continue for centuries.”

The team’s research was published in Scientific progress.

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