Massive northeast Greenland glacier rapidly melting: study

A massive glacier in northeast Greenland that has the potential to raise global sea levels by about 0.5 meters has come unmoored from a stabilizing sill and is crumbling into the North Atlantic Ocean, a study said Thursday.

Losing mass at a rate of 5 billion tons per year, glacier Zachariae Isstrom entered a phase of accelerated retreat in 2012, according to findings published in the U.S. journal Science.

"North Greenland glaciers are changing rapidly," lead author Jeremie Mouginot, assistant researcher at the University of California, Irvine (UCI), said in a statement.

"The shape and dynamics of Zachariae Isstrom have changed dramatically over the last few years. 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 research team used data from aerial surveys and satellite-based observations acquired by multiple international space agencies to study the evolution of Zacharie Isstrom and its northerly neighbor, the Nioghalvfjerdsfjorden glacier.

The results showed that Zacharie Isstrom's acceleration increased by a factor of three in 2012 and that between 2002 and 2014, the area of the glacier's floating shelf shrank by 95 percent.

The team determined that the bottom of Zachariae Isstrom is being rapidly eroded by warmer ocean water mixed with growing amounts of meltwater from the ice sheet surface.

"Zachariae Isstrom is being hit from above and below," said senior author Eric Rignot, professor of Earth system science at the UCI. "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."

Zachariae Isstrom's neighbor, Nioghalvfjerdsfjorden, also is melting rapidly but is receding at a slower rate because it's protected by an inland hill.

The two glaciers make up 12 percent of the Greenland ice sheet and would boost global sea levels by about one meter if they fully collapsed.

"Not long ago, we wondered about the effect on sea levels if Earth's major glaciers were to start retreating," Rignot noted. "We no longer need to wonder; 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." Endit