Global sea levels could rise by up to 13ft if the Western Antarctic Ice Sheet collapses, a ‘significantly’ worse outcome than scientists had predicted, study warns.
Harvard University researchers were working on another project when they realised the West Antarctic ice sheet was producing more water than usual.
Rising global temperatures mean there is a possibility the West Antarctic Ice Sheet, spanning over 750,000 cubic miles, could collapse over the next 1,000 years.
The study authors say that current models suggest the ice melting would increase sea levels by 10ft over current levels, putting many coastal areas underwater.
However, due to a process called water expulsion, as the ice melts the bedrock under the sheet will ‘bounce’, forcing surrounding water into the ocean, causing an extra 3ft of global sea level rise on top of that generated by the melting ice.
The study authors say that current models suggest the ice melting would increase sea levels by 10ft over current levels, putting many coastal areas underwater.
Global sea levels could rise by up to 13ft if the Western Antarctic Ice Sheet collapses, a ‘significantly’ worse outcome than scientists had predicted, study warns
The new prediction considers the impact of this geological process on top of the wider impact of the melting ice.
The process involves solid bedrock beneath the sea moving upwards as the ice sheet melts, pushing surrounding water into the ocean.
This process increases the overall level of sea level rise by about three feet, more than the melting ice would on its own over the next 1,000 years, authors explained.
Co-author doctoral student Linda Pan at the University of Harvard in the United States said the magnitude of the effect ‘shocked us.’
‘Previous studies that had considered the mechanism dismissed it as inconsequential,’ the authors explained.
The researchers were working on another project when they realised the West Antarctic ice sheet was producing more water than usual.
To investigate how the water expulsion mechanism was affecting sea levels around the world, they looked at what was going on beneath West Antarctica.
They explored how quickly material such as bedrock was flowing through the Earth’s mantle, finding that water expulsion was happening faster than predicted.
Pan said: ‘No matter what scenario we used for the collapse of the West Antarctic Ice Sheet, we always found that this extra one metre of global sea level rise took place.’
A total collapse of the ice sheet would add 3.3 feet onto current estimates over the next 1,000 years – bringing it up to 13.3ft, the team explained.
Co-author graduate student Evelyn Powell said if the sheet collapsed that would cause a 10.5ft rise in global sea levels.
‘What we’ve shown is that the water expulsion mechanism will add an additional metre, or 30 percent, to the total.’
Even over the next century, global sea level rise would increase 20 per cent due to the water expulsion mechanism under West Antarctica, the researchers say.
Due to a process called water expulsion, as the ice melts the bedrock under the sheet will ‘bounce’, forcing surrounding water into the ocean, causing an extra 3ft of global sea level rise on top of that generated by the melting ice
A total collapse of the ice sheet would add 3.3 feet onto current estimates over the next 1,000 years – bringing it up to 13.3ft, the team explained
Co-author professor Jerry Mitrovica said every published projection of sea level rise due to the melting of the West Antarctic ice sheet is based on climate modelling.
He said whether the projection extends to the end of this century or longer into the future, the modelling ‘is going to have to be revised upward because of their work.’
The water expulsion effect and the mantle’s low viscosity should be taken into account if future sea level rise estimates are to be accurate, the researchers say.
Mrs Pan said: ‘Sea level rise doesn’t stop when the ice stops melting. The damage we are doing to our coastlines will continue for centuries.’
The findings were published in the journal Science Advances.