The Ocean Is Melting Antarctica

Some 60% of the planet's fresh water stores are locked away in Antarctica's barren tundra. That's a lot of water. For the obvious reasons, we'd all rather keep that water frozen away in the icy interior of the world's southernmost continent than loose it into our already fast-rising oceans.

Unfortunately, new research from NASA's Jet Propulsion Laboratory shows that we may be closer to unleashing an Antarctic flood than previously thought. The study shows that much more of Antarctica's total mass loss is due to warm ocean water than to iceberg calving—which is what scientists previously thought drove shrinkage in the great white south.

So the question is, does that mean Antarctica's ice stores are now more vulnerable to global warming than we thought?

Eric Rignot, a senior scientist at JPL, told me in an email that "the short answer is yes." That's because "existing ice sheet models do not include a warming ocean and realistic ice ocean interactions," he says.

The existing models are predicated on the calving theory—that Antarctica's weight loss was caused by glaciers splitting and falling into the ocean. Rignot's the lead author on this new study, which was published last week in Science.

"The traditional view on Antarctic mass loss is it is almost entirely controlled by iceberg calving," Rignot said during the release. "Our study shows melting from below by the ocean waters is larger, and this should change our perspective on the evolution of the ice sheet in a warming climate."

Which means previous models that sought to calculate just how much ice Antarctica would lose as the planet warmed—and how much would subsequently become water—are way off base. That's problematic, especially because we now know that the continent contains nearly 5% more ice volume than we thought. And it appears to be melting faster than it has in 1,000 years.

If the oceans keep warming, the trend will continue—and Antarctica may keep on losing its ice mass until it looks something like this.