If even a fraction of Antarctica’s ice melts, the resultant sea level rise will reshape coastlines around the world. A new study gets us one step closer to predicting if and when that will happen, by mapping the motion of ice across the entire continent.
The study, published this month in the journal The Cryosphere, analyzed hundreds of thousands of image pairs of Antarctica captured by the Landsat 7 and 8 satellites from 2013 to 2015, along with earlier radar satellite measurements and aerial survey data, to get precise estimates of ice motion and thickness. From all this data, the authors arrived at a stark, if not terribly surprising, conclusion: Antarctica is dumping ice into the sea faster than it used to.
From 2008 to 2015, continent-wide rates of ice discharge increased by about 36 billion tons per year. That’s actually a small number compared with Antarctica’s total annual ice flow—about 2,000 billion tons a year—most of which is replenished by precipitation.
But it’s still significant, especially when you look at where the losses are occurring. Turns out, one region of West Antartica, the Amundsen sea sector home to the famed Pine Island and Thwaites glaciers, drove nearly 80 percent of the increased ice release. This region, which keeps about four feet of sea level in check, has long been considered Antarctica’s “weak underbelly” because of the unstable way its glaciers are grounded.
The study also documented a previously-unknown acceleration of glaciers flowing onto Antarctica’s Getz Ice Shelf, and a dramatic speed-up of the glaciers feeding Marguerite Bay on the western Antarctic Peninsula. Thankfully, it also confirmed that East Antarctica—with its considerably larger mountains of ice—appears to be stable for now.
Whether East Antarctica will remain stable in the future is an open question we’d all really like some answers to.
“The spatial patterns in ice loss are not too terribly surprising,” Ellyn Enderlin, a glaciologist at the University of Maine who was not involved with the study, told Earther. But while the losses may look small, “the fact that the ice sheet is not only out of balance with the climate, but that it has become more out of balance over time, is concerning,” she added.
The most important outcome of the new study may be the techniques that made its estimates possible, which the researchers hope to use to generate more detailed records of what’s moving and shaking in Antarctica.
“At the start of this study there was as single map of [Antarctic] ice sheet velocity, and now we’re in a position where we can generate these at least every year,” lead study author Alex Gardner of NASA’s Jet Propulsion Laboratory told Earther. “If we see rapid change occurring, we can start to modify our field campaigns to make sure we instrument the glaciers that are seeing rapid change.”
That, in turn, will lead to a lot more insight into how and why glaciers retreat and collapse. So, at least this grand experiment of messing with the planetary thermostat will lead to some really stellar Earth science?