The Associated Press reports:

About 12.5 trillion tons (11.3 trillion metric tons) of ice from glaciers in Greenland and Antarctica have melted since 1979, which is enough frozen water to stack ice five feet deep across the continental United States, according to a major scientific report.

A warming Earth is accelerating the melting of the planet’s two major ice sheets, with five-sixths of the melt not coming from hotter air, but from warmer waters eating away at the ice sheets from below and the sides, with glaciers flowing into the oceans, according to a study in Wednesday’s journal Scientific Data. That’s bad news for future sea level rise, the study’s authors said.

“The ice sheets are melting away fast,” said study co-author Eric Rignot, an ice scientist at University of California, Irvine. “We are melting the polar regions, sea level is rising worldwide and will exacerbate the vulnerability of coastal regions.”

The numbers behind the melt are both mind-bogglingly huge and deceptively small.

All that melted ice turned into nearly 3 quadrillion gallons of water (11.3 quadrillion liters), which pushed global sea levels up about an inch (3.1 centimeters) since 1979, on top of other climate factors raising ocean heights, the report said.

An inch may not sound like much, but for every third of an inch (or centimeter) of sea level rise, another 2 to 3 million people get flooded at least once a year, said lead study author Ines Otosaka, an ice scientist at Northumbria University in England.

The Jakobshavn glacier in Greenland is now retreating up to 164 feet (50 meters) a day, Otosaka said. [Continue reading…]