The ice shelves that stretch out from the edges of Antarctica are under attack from “upside-down rivers” of warm water.
Research published yesterday in the journal Science Advances describes a worrying process of glacial erosion that scientists believe future models must account for.
The chain of events begins when layers of ice slide off the edge of glaciers into the ocean. This process of separation involves jagged slipping and sliding that leaves craggy indents on the underside of the ice sheets called “basal channels,” according to Karen Alley of the College of Wooster, an author of the study. As these pockmarked sheets sit on top of the water, they are vulnerable to “buoyant plumes” of warmer ocean water.
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As the water contacts the sheets, it can split them into fragments by melting thin seams in the ice.
It’s long been known that melting Antarctic glaciers are a contributor to sea-level rise. Climate change has exacerbated the rate of ice melt, and this study demonstrates how warmer oceans can play a role in this process.
“These ice shelves in general across Antarctica are very fragile,” said Ted Scambos, a senior research scientist at the University of Colorado’s Cooperative Institute for Research in Environmental Sciences and a co-author on the paper.
“As floating thick plates of ice, they’re exposed to changes in climate on their upper surface and changes in ocean circulation on their lower surface. So if the ocean gets a little warmer, they get these deep channels cut into them.”
And it’s not just the disappearance of ice shelves that scientists should be worried about, explained Scambos. As glaciers move outward toward the water, existing ice shelves serve as natural barriers, pushing back against the force of the ice moving outward. Without them, glacial ice will face little resistance as it shifts toward the ocean.
“We’ve seen events that just showed plainly that glaciers would accelerate if you removed the floating plate that was in front of them,” Scambos said. “So any process that can rapidly remove a glacier—in particular a process that’s tied to climate change—that’s important.”
It’s unclear how much the forces outlined in the study will contribute to sea-level rise and other effects of rising temperatures.
“These effects matter,” Alley said. “But exactly how much, we don’t yet know. We need to.”
Reprinted from Climatewire with permission from E&E News. E&E provides daily coverage of essential energy and environmental news atwww.eenews.net.
