By By Karen Graham Nov 25, 2017 in Environment In a remote region of Antarctica known as Pine Island Bay, the Thwaites and Pine Island glaciers sprawl across a plain over 150-miles-long, widening as they go inland to a reserve of ice two-miles-thick, about the size of Texas. They are melting fast. One of the big concerns about the two Pine Island Bay glaciers is that they are sitting on solid ground and their ice does not displace the ocean. This means that all the water melting from the two glaciers will be added to the total volume of the world's seas. Ice edge of Pine Island Glacier on January 24, 2017. NASA Earth Observatory “There’s no doubt this ice will melt as the world warms,” Holthaus writes. “The vital question is when.” It is estimated at this time we would see a sea level rise of about 3.4 meters (11.2 feet). And even though scientists used to think it would take thousands of years for Antarctica's ice sheets to melt, new evidence suggests this could happen in just a few decades. Marine ice-cliff instability Keep in mind that Antarctica is a giant landmass, about half the size of Africa. And before humans started burning fossil fuels, the ice was fairly stable. But humans triggered global warming and an insidious change began to take place in the atmosphere. Now, as more and more carbon dioxide is trapped in the atmosphere, the Earth is heating up. The Thwaites Glacier part of the West Antarctica Ice Sheet is undergoing accelerated melt along with a number of other glaciers that could see sea levels rise by between 10 and 13 feet. NASA The evidence points to Holthaus says this is partially the result of something called “marine ice-cliff instability.” This instability is caused because as the ocean floor gets deeper toward the center of this part of Antarctica, each new iceberg that breaks away exposes taller and taller cliffs. "Ice gets so heavy that these taller cliffs can’t support their own weight. Once they start to crumble, the destruction would be unstoppable," He wrote. Fijian Prime Minister Frank Bainimarama will preside over the 12-day climate summit, after his island nation was hit by flooding following powerful Cyclone Winston in 2016 STEVEN SAPHORE, NEW ZEALAND DEFENCE FORCE/AFP “The new evidence says that once a certain temperature threshold is reached, ice shelves of glaciers that extend into the sea, like those near Pine Island Bay, will begin to melt from both above and below, weakening their structure and hastening their demise, and paving the way for ice-cliff instability to kick in.” Unstoppable Ice Collapse Not every scientist agrees with Holthaus. Those who are concerned refer back to a Time is running out on mankind's ability to keep global warming below two degrees Celsius, scientists say. LIONEL BONAVENTURE, AFP According to the study, estimates of how high sea levels could rise in this century were significantly higher than previous estimates. Instead of a three-foot increase in ocean levels by the end of the century, six feet was more likely, according to DeConto and Pollard’s findings. Scientists do agree the science isn’t yet certain. Not enough is understood about the And while there is no doubt these glaciers will melt, the big question is - When? According to one meteorologist, Eric Holthaus, who published the story in Grist a few days ago, if the two glaciers collapse, every shoreline and coastal city worldwide could be inundated with water, leaving hundreds of millions of climate refugees homeless.One of the big concerns about the two Pine Island Bay glaciers is that they are sitting on solid ground and their ice does not displace the ocean. This means that all the water melting from the two glaciers will be added to the total volume of the world's seas.“There’s no doubt this ice will melt as the world warms,” Holthaus writes. “The vital question is when.” It is estimated at this time we would see a sea level rise of about 3.4 meters (11.2 feet). And even though scientists used to think it would take thousands of years for Antarctica's ice sheets to melt, new evidence suggests this could happen in just a few decades.Keep in mind that Antarctica is a giant landmass, about half the size of Africa. And before humans started burning fossil fuels, the ice was fairly stable. But humans triggered global warming and an insidious change began to take place in the atmosphere. Now, as more and more carbon dioxide is trapped in the atmosphere, the Earth is heating up.The evidence points to climate change , and to figure out our present predicament, scientists have looked at the end of the last ice age, about 11,000 years ago, when global temperatures stood at roughly their current levels. The evidence shows the Pine Island Bay glaciers collapsed back then, flooding coastal regions.Holthaus says this is partially the result of something called “marine ice-cliff instability.” This instability is caused because as the ocean floor gets deeper toward the center of this part of Antarctica, each new iceberg that breaks away exposes taller and taller cliffs. "Ice gets so heavy that these taller cliffs can’t support their own weight. Once they start to crumble, the destruction would be unstoppable," He wrote.“The new evidence says that once a certain temperature threshold is reached, ice shelves of glaciers that extend into the sea, like those near Pine Island Bay, will begin to melt from both above and below, weakening their structure and hastening their demise, and paving the way for ice-cliff instability to kick in.”Not every scientist agrees with Holthaus. Those who are concerned refer back to a study published in 2016 by climatologists Rob DeConto at the University of Massachusetts-Amherst and David Pollard at Penn State University. The study was the first to incorporate the latest understanding of marine ice-cliff instability into a continent-scale model of Antarctica.According to the study, estimates of how high sea levels could rise in this century were significantly higher than previous estimates. Instead of a three-foot increase in ocean levels by the end of the century, six feet was more likely, according to DeConto and Pollard’s findings.Scientists do agree the science isn’t yet certain. Not enough is understood about the mechanics of glaciers or the physics of ice to be sure. But climate researchers agree the new evidence is pointing in a deeply disturbing direction. “Next to a meteor strike, rapid sea-level rise from collapsing ice cliffs is one of the quickest ways our world can remake itself,” Holthaus says. “This is about as fast as climate change gets.” More about Antarctica, Thwaites, Pine allen, doomsday glacier, coastal flooding Antarctica Thwaites Pine allen doomsday glacier coastal flooding