Global warming rapidly melts massive Greenland glacier

A massive glacier in northeast Greenland has dramatically melted in the past decade and would raise global sea levels by a foot and a half if it thawed completely, according to a study published Thursday.

It was a "surprise" to learn how fast the large chunk of ice was shrinking, Jeremie Mouginot, lead scientist of the report, told USA TODAY in an email.

The glacier holds enough water to raise global sea levels by more than 18 inches if it were to melt away to nothing, but no timetable exists for how long that process could take, according to the study, published in the peer-reviewed journal Science.

"The glacier has profoundly transformed in only 10 years," Mouginot, of the University of California, Irvine, said. "The glacier is now breaking up and calving high volumes of icebergs into the ocean, which will result in rising sea levels for decades to come."

The melting of the "Zachariae Isstrom" glacier is a result of warming temperatures both in the sea and the air, said study co-author Eric Rignot, also of UC-Irvine. "The top of the glacier is melting away as a result of decades of steadily increasing air temperatures, while its underside is compromised by currents carrying warmer ocean water, and the glacier is now breaking away into bits and pieces and retreating into deeper ground," he said.

The glacier is near a large one also melting rapidly but at a slower rate. The two chunks of ice make up 12% of the Greenland ice sheet and would boost global sea levels by more than 39 inches if they both totally collapsed, a process that would likely take centuries.

The planet's two major ice sheets are in Greenland and Antarctica, and together make up 99% of the freshwater ice on Earth, according to the National Snow and Ice Data Center. In Greenland, ice sheet decline continues to outpace accumulation, because warmer temperatures have led to increased melt and faster glacier movement at the island's edges, the data center said.

"Not long ago, we wondered about the effect on sea levels if Earth's major glaciers were to start retreating. We no longer need to wonder," Rignot said. "For a couple of decades now, we've been able to directly observe the results of climate warming on polar glaciers. The changes are staggering and are now affecting the four corners of Greenland."