Science

Antarctica would become ice-free if temperatures rise by 10C, study warns

The researchers also say that, once melted, Antarctic ice will be gone forever as changes in the ice sheet are not easily reversible.

Antarctica will become virtually ice-free if global temperatures exceed 10C above pre-industrial levels, scientists have warned.

Researchers have said the continent’s long-term contribution to sea levels will “dramatically increase and exceed that of all other sources” unless the targets to limit global warming are met.

They said the fate of Antarctica “lies in our hands” as the team warned that even a 2C rise in temperatures above pre-industrial levels poses a threat to coastal cities, with a 2.5 metre rise in global sea levels predicted just from Antarctica alone.

In their findings, published in the journal Nature, the researchers also say that, once melted, Antarctic ice will be gone forever as changes in the ice sheet are not easily reversible.

Study co-author Dr Anders Levermann, who is a researcher at the Potsdam Institute for Climate Impact Research in Germany, said: “Antarctica is basically our ultimate heritage from an earlier time in Earth’s history.

“It’s been around for roughly 34 million years. Now our simulations show that once it’s melted, it does not regrow to its initial state even if temperatures eventually sank again.

“Indeed, temperatures would have to go back to pre-industrial levels to allow its full recovery – a highly unlikely scenario. In other words: What we lose of Antarctica now, is lost forever.”

The aim is to keep the global temperature rise below 2C but ideally less than 1.5C – in line with the 2015 Paris Agreement.

The researchers used computer modelling to calculate which warming levels would cause the ice in Antarctica to become unstable and eventually melt into the ocean.

Dr Ricarda Winkelmann, who is also a researcher at the Potsdam Institute for Climate Impact Research and corresponding author of the study, said: “We find that already at 2 degrees of warming, melting and the accelerated ice flow into the ocean will, eventually, entail 2.5 metres of global sea level rise just from Antarctica alone.

“At 4 degrees, it will be 6.5 metres and at 6 degrees almost 12 metres if these temperature levels would be sustained long enough.”

At more than 10C of warming above pre-industrial levels, Antarctica will become virtually ice-free, the researchers said.

According to Dr Winkelmann, Antarctica holds more than half of Earth’s fresh water, frozen in a vast ice-sheet which is nearly five kilometres thick.

She said: “We decide now whether we manage to halt the warming.

“So Antarctica’s fate really lies in our hands – and with it that of our cities and cultural sites across the globe, from Rio de Janeiro’s Copacabana to Sydney’s Opera House.”

Commenting on the research, Jonathan Bamber, professor of glaciology at the University of Bristol, who was not involved in the study, said: “This study provides compelling evidence that even moderate climate warming has incredibly serious consequences for humanity and those consequences grow exponentially as the temperature rises.

“The committed sea level rise from Antarctica even at 2 degrees warming represents an existential threat to entire nation states.

“We’re looking at removing nations from a map of the world because they no longer exist.

“It doesn’t get much more serious than that.”

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