New research indicates that, due to global warming, the West Antarctic Ice Sheet (WAIS) may be headed for an unavoidable and disastrous collapse, triggering a rapid rise in sea levels. Photograph by Natacha Pisarenko / AP

One of the first people to propose that climate change could result in rapid sea-level rise was an eccentric British geographer named John Mercer. A hesitant speaker in public, Mercer was less restrained in private. He was once arrested for jogging naked. It was said that he liked to do his fieldwork in the nude—a curious habit for a man who studied glaciers.

In a seminal paper published in 1968, Mercer proposed that the West Antarctic Ice Sheet, known in scientific circles as WAIS, was vulnerable to collapse. The reason, he wrote, was that the ice sheet rests on land that is below sea level. It is buttressed by floating ice shelves that extend far out to sea, but were these to disintegrate, Mercer wrote, then “changing horizontal forces” would cause the ice sheet to lift off its base. At that point, the sea would rush in and WAIS would start to warm from below as well as above. This would initiate the ice sheet’s demise, which would be “rapid, perhaps even catastrophic.” Several meters of sea-level rise would ensue.

More recent research has tended to confirm Mercer’s worst fears. The latest example comes from a study published Wednesday, in the journal Nature. “Antarctic Model Raises Prospect of Unstoppable Ice Collapse,” ran the headline in the news story that accompanied it.

The new paper, coauthored by Rob DeConto, of the University of Massachusetts at Amherst, and David Pollard, of Pennsylvania State University, arose out of frustration. The two researchers had spent years working on a computer model that did not seem to capture rises in sea level that were already known to have taken place. Before the last ice age, about a hundred and twenty thousand years ago, for instance, sea levels were at least twenty feet higher than they are now. But DeConto and Pollard found that unless they programmed the model with temperatures that were unrealistically high for that period it could not account for such levels.

Then the two got an idea from a colleague, Richard Alley, also of Penn State. Alley suggested that they look at what would happen if the floating ice shelves were lost. This would leave towering cliffs of ice exposed to the sea, which could make them vulnerable to rapid collapse. (A version of this process seems already to be under way in parts of Greenland.)

When DeConto and Pollard revised their model to account for this possibility, the results, as the Times put it, were “striking.” The revised model could account for earlier sea-level rises. More significantly, it suggested that what had happened then could easily happen again. The researchers concluded that just a few more decades of “unabated” carbon emissions could result in more than three feet of sea-level rise from WAIS by the end of this century. (The over-all rise would be much greater, as ice would also be lost from Greenland and from mountain glaciers.) Over the longer term, melt from Antarctica could raise sea levels by fifty feet.

This is, of course, alarming news for those living near sea level, which is to say anyone in New York or Boston or New Orleans or Miami or Mumbai or Jakarta or Guangzhou. And it couldn’t come at a much more alarming time. In spite of the flood of disturbing reports coming from both the Antarctic and the Arctic—just a few days ago, the National Snow and Ice Data Center reported that the extent of the Arctic ice cap in winter had hit a record low for the second year in a row—the issue of climate change has rarely come up during the Presidential primary campaign. To the extent that the Republican candidates have addressed the issue at all, it has only been when forced to, and the results have been—well, let’s just say that no one is winning any ribbons at this science fair. Trump has repeatedly used Twitter—his favored policy platform—to scoff at the very notion of climate change. “Hoax” and “con job” are some of his more nuanced comments. “Bullshit” is another.

Ted Cruz is, if anything, worse; he recently claimed that the federal government was “cooking the books” to demonstrate warming that doesn’t exist. Cruz has said he will rescind rules the Environmental Protection Agency has put in place to limit emissions from power plants, while Trump has said he would eliminate the agency altogether. (The E.P.A.’s Clean Power Plan rules are being challenged in a suit brought by more than two dozen states and many industry groups; that case is expected to be heard by the D.C. Circuit Court in June.) Even with the power-plant rules, it’s possible that global temperatures will rise enough to set in motion the sort of catastrophic melting of West Antarctica that John Mercer warned about almost half a century ago. Without the rules, disaster is looking like an increasingly good bet.