A glacier in West Antarctica, referred to as "the world's most risky", might completely melt away and trigger a rapid and "catastrophic" sea-level rise, new research warns.
There are plenty of ominous indicators of the consequences of climate change, but few are more worrying to scientists than the ice sheets of Antarctica at our planet's southern pole.
At 300,000sq km it's the size of Victoria and Tasmania combined.
And once the "instability" begins, nothing could prevent the ice from melting completely - potentially drowning some low-lying areas of coastline.
Depending on how fast global warming continues and the nature of the glacier's instability, extensive ice loss would start in 600 years according to modeling simulations in the research.
The Thwaites glacier is situated in Antarctica. Study researcher Alex Robel, from the US Georgia Institute of Technology, said that if instability was triggered, the ice sheet may still be lost regardless if global warming stops.
"It will keep going by itself and that's the worry", he said.More news: Free Slurpees for Everyone on 7-Eleven Day!
But he added: "Climate variations will still be important after that tipping point because they will determine how fast the ice will move".
The warmer ocean water also hollows out the bottom of the ice, adding a little more water to the ocean.
If and when the glacier becomes unstable, the after-effects can be considered "catastrophic". Also, Antarctica is an ice leviathan.
The results showed the glacier was more in danger of becoming unstable that previously thought.
The ice giant is heading towards a doomsday "instability" which once crossed means it could all float out into the sea and melt within 150 years, the NASA-funded study found.
She continued and said, "That would make for a sea-level rise of about half a meter (1.64 feet)".
That ice loss is part of a broader trend: The entire Antarctic ice sheet is melting almost six times as fast as it did 40 years ago. But new analysis of the instability embedded in the continent's glaciers suggests large portions of the ice shelf are likely to reach a tipping point, guaranteeing significant levels of melting and sea level rise.More news: Study finds possible link between sugary drinks and cancer
The grounding line is the line between where the ice sheet rests on the seafloor and where it extends over the water. "The process becomes self-perpetuating". This instability is unlikely to be found only in the Thwaites Glacier.
By the end of this century, sea levels are expected to rise by up to two feet (60cm). Much of the city's naval base would be underwater.
Most of that water is frozen in masses of ice and snow that can be up to 10,000 feet (3 kilometres) thick.
The very big Thwaites glacier covers 293,000sq kms - about half the area of the United Kingdom.
But it's Thwaites' protective effect on neighbouring glaciers that NASA is most anxious about.
Unlike the melting of ice sheets on land, sea ice melting does not raise sea levels but the loss of the reflective white ice leads to more of the sun's heat being absorbed in the ocean, increasing the pace of heating.
Glacier collapse has a lot to do with the geometry of the bedrock underpinning the ice.More news: Frank Lampard: Chelsea need to improve fitness