"Large portions of the massive ice sheet in West Antarctica are melting — and there's likely nothing we can do to stop the decline," writes Brad Plumer for Vox, Ezra Klein's new media venture, about a new study by researchers at NASA and the University of California, Irvine.
The key question is how quickly all that ice will melt into the ocean and push up sea levels in the decades and centuries ahead.
For readers concerned about sea-level rise, the study makes some important changes to what had been predicted because the glaciers "appear to be dwindling even faster than scientists thought." It "means forecasts for future sea-level rise may have to be revised upward. (The current consensus holds that global average sea levels will rise between 1 foot and 4 feet by 2100,) adds Plumer.
Note that "ice sheet" and "glaciers" are used interchangeably by both Plumer and NASA.
According to the UC Irvine press release, the study incorporated "40 years of observations – that six massive glaciers in the Amundsen Sea sector 'have passed the point of no return,' according to glaciologist Eric Rignot, a UC Irvine Earth system science professor who is also with NASA’s Jet Propulsion Laboratory."
One final note on why the ice sheets are melting. "It's not because the air in Antarctica has been heating up. Instead, strong winds are pulling warmer water from the deep oceans toward the glaciers and melting the ice sheet from below," writes Plumer. "Natural fluctuations and the ozone hole over Antarctica may also be playing a role."