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 5 feet (1.5 meters) 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.”