New Science: Greenland Melt Could Be Making Sea-Level Rise Even Worse

"Rising global temperatures may be affecting the Greenland ice sheet — and its contribution to sea-level rise — in more serious ways that scientists imagined, a new study finds. Recent changes to the island’s snow and ice cover appear to have affected its ability to store excess water, meaning more melting ice may be running off into the ocean than previously thought.

That’s worrying news for the precarious Greenland ice sheet, which scientists say has already lost more than 9 trillions tons of ice in the past century — and whose melting rate only continues to increase as temperatures keep warming up. NASA estimates that the Greenland ice sheet is losing about 287 billion tons of ice every year, partly due to surface melting and partly due to the calving of large chunks of ice. Because of the ice sheet’s potential to significantly raise sea levels as it runs into the ocean, scientists have been keeping a close eye on it — and anything that might affect how fast it’s melting.

The new study, published Monday in the journal Nature Climate Change, focuses on a part of the ice sheet known as “firn” — a porous layer of built-up snow that slowly freezes into ice over time. It’s considered an important part of the ice sheet because of its ability to trap and store excess water before it’s able to run off the surface of the glacier, an essential service that helps mitigate the sea-level rise that would otherwise be caused by the runoff water."

Chelsea Harvey reports for the Washington Post January 4, 2016.