Tuesday, December 13, 2016

New Studies Say Greenland’s Ice Sheet Could Melt Far Faster Than Scientists Believed

[Time] Scientists who study climate change have warned for years that sea level rise due to the melting polar ice caps could devastate coastal cities. But the scale of the damage—and how quickly it would unfold—has remained a matter of debate. Now, two new studies published in the journal Nature undercut key assumptions about Greenland’s ice sheet—a key site of melting ice—and shows just how much more scientists need to learn to understand how devastating sea level rise may be.
The first study suggests that for extended periods over the last several million years, Greenland’s ice sheet lost most of its ice. That challenges the assumption that the island’s ice sheet is relatively stable, even in the face of warming. (The most recent report from the Intergovernmental Panel on Climate Change doesn’t include estimates of possible sea level rise from Greenland melting before 1990, in part because scientists didn’t know much about the long-term history of the ice sheet.) The finding could lead modelers to revise upward assumptions about how much melting ice from Greenland will contribute to sea level rise. If all the ice on Greenland melted, it would raise sea levels globally nearly 25 feet (7.4 m)—enough to swamp coastal cities.

“The scenarios at the moment basically assume a stable Greenland ice sheet,” says study author Joerg Schaefer, a research professor at Columbia University. “I think there’s a big question mark now behind that assumption.” Read More