Collapsing ice sheets at the poles are powerful symbols of a warming world, but new research suggests they may also be ramping up the global impact of climate change.
Conventional wisdom holds that the most worrying consequence of melting polar ice will be the contribution of these enormous water stores to worldwide sea levels.
But two new research papers published in the journal Nature challenge this notion, revealing once again the complexity of environmental factors scientists must take into consideration when predicting climate change.
Global temperatures are currently on track to rise about 3C above pre-industrial levels by the end of the century.
This is expected to accelerate the melting of ice sheets and raise global sea levels, threatening coastal communities around the world and posing an existential threat to low-lying islands.
But warmer meltwater entering the oceans will have more complex effects than simply changing sea levels – weakening ocean currents such as the Gulf Stream and changing air temperatures on both sides of the Atlantic.
Scientists have already warned of a slower Atlantic meridional overturning circulation (Amoc); the currents transporting warm water from the tropics via the Gulf Stream to the Arctic.
In their new analysis, an international research team predicted “climate chaos” as more meltwater gushes into the oceans, producing a marked impact on weather within decades.
“Melt from these ice sheets is going to significantly disrupt the global climate making temperatures in some areas vary much more from one year to the next,” said Professor Nick Golledge from Victoria University of Wellington.
“This unpredictability is going to prove extremely disruptive for all of us, and will make adaptation and planning much more difficult.”
In the second part of their analysis the scientists examined past sea level rise data to establish whether it supported the controversial idea that ice cliff collapses could add more than a metre to rising seas by 2100.
They found that while the overall rise in sea levels is likely to be more modest, its impact would still be destructive.
“Water levels would not simply rise like a bathtub,” said Professor Natalya Gomez from McGill University.
“Some areas in the world, such as the island nations in the Pacific, would experience a large rise in sea level, while close to the ice sheets the sea level would actually fall.”
The scientists said current policies based on the Paris climate agreement do not fully take the effects of ice sheet melt into account.
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