Time is rapidly running out to save Antarctica and the rest of the world from the catastrophic runaway effects of climate change, scientists have warned.
Vital decisions made in the next decade will determine the fate of the continent and whether or not a surge in sea levels swamps coastal cities, new research suggests.
If not enough is done to curb greenhouse gas emissions, changes to the Antarctic environment will result in global sea levels rising by more than a metre (3.3ft) by 2070.
Eventually the unstoppable forces unleashed would see the collapse of the entire West Antarctic Ice Sheet and an overwhelming 3.5 metre (11.5ft) rise in sea levels, the study predicts.
There could also be serious knock-on effects on global ocean currents and marine life.
In contrast, a significant cut in emissions would protect the vulnerable ice sheets and avert the threat of major sea level rises.
The international team, including UK experts from Imperial College London, predicted the likely outcome of two far-reaching scenarios.
Under the first, greenhouse gas emissions continue unabated, causing global temperatures to soar to almost 5C above what they were in 1850.
The second scenario would see governments rally to cut emissions and keep global warming to below 2C. Global sea levels would then only rise by around half a metre due to effects that have been irreversible since 2010.
Professor Martin Siegert, from the Grantham Institute at Imperial College, said: “Some of the changes Antarctica will face are already irreversible, such as the loss of some ice shelves, but there is a lot we can prevent or reverse.
“To avoid the worst impacts, we will need strong international cooperation and effective regulation backed by rigorous science. This will rely on governments recognising that Antarctica is intimately coupled to the rest of the Earth system, and damage there will cause problems everywhere.”
Scientists have long known that the effects of global warming are amplified in Antarctica, causing changes that can be felt around the world.
The continent is surrounded by floating ice shelves that hold back ice on the land. Without them, there is nothing to stop vast amounts of grounded ice forming the Antarctic Ice Sheet from flowing into the Southern Ocean and raising sea levels.
In total, Antarctica stores enough frozen water to lift global sea levels by 58 metres (190ft).
The influx of large amounts of fresh water from melting Antarctic ice would also alter ocean currents on a global level. The consequences could be dramatic – for instance, stalling the Gulf Stream that channels warm water past the British Isles and causing temperatures in the UK to plunge.
In addition, high levels of carbon dioxide in the atmosphere could reach a tipping point beyond which no more of the greenhouse gas can be absorbed by the Southern Ocean.
This would accelerate global warming and increase ocean acidity, harming marine life around the world.
Findings from the new study are reported in the journal Nature.
The scientists also warned that there was no guarantee a moratorium on mining in Antarctica would still be in place by 2070.
Lifting the ban could result in severe damage to the Antarctic environment, while the loss of land ice could result in unsustainable levels of tourism and the spread of unwanted invasive species.
A second international study published in Nature highlighted evidence of Antarctica’s increasing contribution to rising sea levels.
Satellite surveys showed that prior to 2012, Antarctica lost ice at a steady rate of 76 billion tons per year. Since then there had been a sharp three-fold increase, with the continent shedding 219 billion tons of ice annually between 2012 and 2017.
Co-author Professor Donald Bren, from the University of California at Irvine, said: “We view these results as another ringing alarm for action to slow the warming of our planet.”
Louisa Casson, from the environmental group Greenpeace UK, said: “Right now we have an opportunity to protect the Antarctic, the incredible home of penguins and whales that also affects our global climate.
“Today’s grave warnings must act as a catalyst for action to urgently scale up climate action on land and at sea.”