“We may be headed for an ice apocalypse which could result in the flooding of coastal cities before the end of this century,” writes long-time Slashdot reader whoever57. Grist reports on two of the largest and fastest-melting glaciers in Antarctica which “hold human civilization hostage.”
There’s no doubt this ice will melt as the world warms. The vital question is when… Together, they act as a plug holding back enough ice to pour 11 feet of sea-level rise into the world’s oceans — an amount that would submerge every coastal city on the planet… Each new iceberg that breaks away exposes taller and taller cliffs… In the past few years, scientists have identified marine ice-cliff instability as a feedback loop that could kickstart the disintegration of the entire West Antarctic ice sheet this century — much more quickly than previously thought. Minute-by-minute, huge skyscraper-sized shards of ice cliffs would crumble into the sea, as tall as the Statue of Liberty and as deep underwater as the height of the Empire State Building. The result: a global catastrophe the likes of which we’ve never seen… When [land-based ice] falls into the ocean, it adds to the overall volume of liquid in the seas. Thus, sea-level rise…. All this could play out in a mere 20 to 50 years — much too quickly for humanity to adapt…
A lot of this newfound concern is driven by the research of two climatologists: Rob DeConto at the University of Massachusetts-Amherst and David Pollard at Penn State University. A study they published last year was the first to incorporate the latest understanding of marine ice-cliff instability into a continent-scale model of Antarctica… 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. But if carbon emissions continue to track on something resembling a worst-case scenario, the full 11 feet of ice locked in West Antarctica might be freed up, their study showed.
If sea levels rise by six feet, “around 12 million people in the United States would be displaced, and the world’s most vulnerable megacities, like Shanghai, Mumbai, and Ho Chi Minh City, could be wiped off the map.”
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