I’m a biased observer on this topic—having spent several weeks as a U.S. Antarctic Program metalworker, welding together parts for a West Antarctic field camp—but I think it’s fair to say that the most apocalyptic scenario for global-warming-induced sea-level rise involves the collapse of the West Antarctic Ice Sheet into the ocean. The sheet alone contains enough water to cause a roughly five-meter increase in sea levels around the world—which, as visible in these handy maps, would inundate Washington, D.C., all of Southern Florida, and a lot of Bangladesh, among other places.
And that extra water would only be the start, according to a paper recently published in Science. After the sheet collapsed, the bedrock underneath—much of which is currently below sea level—would then begin to rebound upward, freed from the weight of all the ice that used to be on top of it, thereby displacing seawater and raising the level of the oceans even further (this process would begin nearly immediately and then continue on for thousands of years). Moreover, the "bulge" of water in the Southern Ocean that currently sits near West Antarctica—created, believe it or not, by the gravity of all that ice—would start flowing off to other parts of the world, raising sea levels further still. If that wasn't enough, the earth’s rotation would likely shift as a result of the sheet collapsing, with the South Pole moving some 500 meters in one direction and the North Pole moving 500 meters in the other.
That’s why Yale Environment 360’s recent interview with Robert Bindschadler, a glaciologist studying West Antarctica, is so disconcerting. Bindschadler and his team have discovered that the Pine Island Glacier—one of the main glaciers flowing out of West Antarctica—has sped up significantly in the past five years and is now creeping toward the sea at the blistering (for a glacier) rate of a foot per hour. The best explanation for this acceleration is that warmer water from the Southern Ocean is melting the underside of the floating ice shelf that forms the transition zone between the glacier and the open sea.
According to Bindschadler, current models appear to underestimate the rate at which glaciers like the Pine Island Glacier are accelerating, thereby underestimating future sea-level rises as a result of global warming. He says he wouldn’t be surprised to see one meter of sea-level rise by mid-century. That would be a whole lot more than predicted in the last report from the Intergovernmental Panel on Climate Change, which didn’t take into account any changes to the ice sheets in Greenland or Antarctica. And while it won't be enough of a rise to make the movie Waterworld look like eco-prophecy, it’s enough to cause serious suffering in the world’s costal regions, with the unfortunate prospect of more to follow.