New NASA-funded research warns that because of human-caused global heating, West Antarctica's massive Thwaites Glacier is at risk of reaching a tipping point that could raise the global sea level by about 20 inches.
Thwaites fglacoer measures approximately 70,000 miles (about the size of the U.S. state of Florida) and scientists have warned it is reaching "tipping point", meaning it will be impossible to reverse the process of the glacier melting and raising sea levels.
The situation is so bad that it could happen even under present-day ice-melting rates.
And once the "instability" begins, nothing could prevent the ice from melting completely - potentially drowning some low-lying areas of coastline. Now, a study says that instability hidden within Antarctic ice is likely to accelerate its flow into the ocean and push sea level up at a more rapid pace than previously expected.
The doomsday prediction came after 500 ice-flow models of the glacier all predicted the instability would be triggered if the rate of ice melt due to warming oceans stayed at today's levels.
The simulations show that even if we do stop climate warming in the future, instability in Thwaites will keep feeding water into the global ocean at extremely fast rates compared to the baseline value. They applied the math to simulations of possible future fates of marine glaciers like Thwaites Glacier. "It will keep going by itself, and that's the worry", said Robel.
But he added: "Climate variations will still be important after that tipping point because they will determine how fast the ice will move".
Arctic sea ice floats in water, so even when it melts we don't see a change in sea level.
What sounds even more awful is that even if climate change declined and global warming stopped at some point, the glacier would remain unstable and would push ice into the sea at an accelerated rate in the coming centuries.
The Thwaites Glacier is a large mass of ice born from snow that's been compressed over time.
But Thwaites prevents its neighbour glaciers from flowing into the ocean, too.
NASA JPL scientist Helene Seroussi, who worked on the research together with Robel, mentioned that the glacier could lose all of its ice over the following 150 years.
"That would make for a sea level rise of about half a metre". 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.
The grounding line is the line between where the ice sheet rests on the seafloor and where it extends over the water.
"Once [the] ice is past the grounding line and only over water, it's contributing to sea level because buoyancy is holding it up more than it was before", Robel said. As more and more ice flows out, and as more icebergs calve, more and more of the glacier is exposed to the ocean.
Mr Seroussi added: "The process becomes self-perpetuating".
Earlier this year, NASA added fuel to the fire by discovering a huge void lurking beneath Thwaites Glacier.
By the end of this century, sea levels are expected to rise by up to two feet (60cm).
As it grows, Thwaites will disintegrate faster and faster, potentially triggering a global catastrophe.
The conclusion was that the glacier is racing towards an irreversible melting point.