The Great Glacier Melt Spreads to Greenland’s North
A Greenland glacier that holds the equivalent of 19 inches of sea-level rise has been melting at an accelerated rate since 2012, shedding as much as 5 billion metric tons a year, according to a new study published in the journal Science.
While scientists have observed the melting of Greenland’s southern glaciers, the Zachariæ Isstrøm glacier is the first major glacier in the northern part of the country to show similar losses.
“That may be an indication that climate warming is spreading toward the poles,” said Jeremie Mouginot, the study’s lead author and an associate project scientist at the University of California, Irvine.
Working with researchers at NASA’s Jet Propulsion Laboratory and the University of Kansas, the team used aerial surveys, radar, laser profiling systems, and satellite observations from multiple international space agencies to piece together 40 years of data.
They found that the Zachariæ glacier is rapidly eroding from the bottom thanks to warmer ocean water and increasing levels of meltwater that are affecting the ice sheet surface.
“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,” Eric Rignot, study coauthor and UC Irvine professor of Earth system science, said in a statement.
“From our record, it is the first time Zachariæ has retreated so far inland and has lost its floating ice shelf,” Mouginot said.
The researchers also pointed out a neighboring glacier, Nioghalvfjerdsfjorden, which is experiencing rapid ice melts but at a slower pace than Zachariæ. The two glaciers make up 12 percent of Greenland’s ice sheet. If both fully collapsed, it would mean 39 inches of sea-level rise for the world.
“At the present rate of mass loss, it would take millennia for the glacier to completely disappear,” Mouginot said. “But we do not know how fast the glacier will flow in the coming decades.”
Scientists estimate Greenland’s 650,000-square-mile ice sheet is losing 303 billion tons of ice on average per year. But more ice loss from the north could mean an acceleration of the Intergovernmental Panel on Climate Change’s projection of sea-level rise of 1.6 feet to 3.2 feet by the end of the century. If the entire ice sheet melted, it would raise sea levels by more than 20 feet worldwide.
“Not long ago, we wondered about the effect on sea levels if Earth’s major glaciers were to start retreating,” Rignot said. “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.”