Greenland’s ice sheet is melting differently than initially predicted, creating solid ice sheets instead of porous ice that can reabsorb (and refreeze) meltwater, a new report says.
“These slabs are instead sending meltwater spilling into the ocean, threatening to increase the country’s contribution to sea level rise by as much as 2.9 inches by 2100,” the University of Colorado Boulder’s Cooperative Institute for Research in Environmental Sciences said Wednesday.
“Even under moderate climate projections, ice slabs could double the size of the runoff zone by 2100,” researcher Mike MacFerrin said in a statement. “Under higher emissions scenarios, the runoff zone nearly triples in size.”
The results of their findings were published in the journal Nature on Wednesday.
They study shows not only that billions of tons of ice are being shed, but also that the remaining ice is becoming more dense, explained National Geographic. These impermeable ice slabs expanded by 25,000 square miles between 2001 and 2013, the researchers said.
Researchers including MacFerrin have been studying the ice slabs since 2012 after finding unexpected sections of solid ice in the core samples they were extracting, where they had initially expected to see thin “lenses” of ice.
They’ve been mapping the slabs ever since, the researchers’ statement said.
Given that the world’s nations show little if any inclination to reduce emissions and greenhouse gases, the climate may very well continue to warm. A moderate version of that could increase the ice-slab area by the size of Colorado, while a higher-emissions scenario could boost that runoff zone by the size of Texas, the researchers said.
That’s not even counting the existing sources of sea-level rise, such as calving icebergs, that Greenland is already contributing.
“As the climate continues to warm, these ice slabs will continue to grow and enhance other meltwater feedbacks,” said paper coauthor and National Snow and Ice Data Center researcher Mahsa Moussavi. “It’s a snowball effect: More melting creates more ice slabs, which create more melting, which, creates again more ice slabs.”
While the edges of the ice sheet have long been known to be rapidly melting, the center has behaved differently — until now.
“The majority of the interior has been pretty stable,” MacFerrin told Science News. “Now we’re watching an ice sheet transform itself before our eyes…. The cold, boring interior of Greenland is waking up.”