NASA Says Global: Zachariae Isstrom Glacier’s Ice Sheet In Greenland Melting

They believe that Zachariæ Isstrøm may continue retreating rapidly, and that the Nioghalvfjerdsfjorden ice shelf will become vulnerable to break up in the near future if the thinning it is experiencing continues. The consequences will be felt for decades to come. Because Zachariæ Isstrøm is on a downslope, it’s disappearing faster. The glacier’s grounding line-the critical point where the ice is thin enough to begin floating and loses contact with its bed-retreated a kilometer between 1992 and 2011, but it hasn’t budged since.

“Now it’s unstable and it’s going to retreat even more”, says team member Jeremie Mouginot of the University of California, Irvine.

The glacier is dumping “high volumes of icebergs into the ocean, which will result in rising sea levels for decades to come”, he said. The NASA satellite data used are from the joint NASA/USGS Landsat program.

Mouginot and his colleagues drew on 40 years of satellite data and aerial surveys to show that the enormous Zachariae Isstrom glacier began to recede three times faster from 2012, with its retreat speeding up by 125 meters [410 feet] per year every year until the most recent measurements in 2015.

“Zachariae Isstrom is being hit from above and below”, said the study’s senior author Eric Rignot, Chancellor’s Professor of Earth system science at UCI, and Joint Faculty Appointee at JPL.

While air temperatures have warmed, causing boosted surface runoff, Paden said ice loss from calving off the front of the glacier into the ocean accounts for most of the ice mass reduction from Zachariae Isstrom.

Another large glacier near Zachariae Isstrom – known as Nioghalvfjerdsfjorden – is also melting but not as quickly because it is protected by an inland hill. In the worst case scenarios, all of these Greenland glacier sheets could collapse, raising the sea level by several feet. They note that two other major areas of Greenland with outlet glaciers in vulnerable valleys-including the Jakobshavn and Petermann Glaciers-are also shrinking rapidly. The latter two sectors hold enough water to raise global sea level by 2 feet (0.6 meters) each, and both are also undergoing significant changes at present.

The bleak assessment of the glaciers’ retreat comes only months after NASA launched an urgent six year project called Oceans Melting Greenland, aptly contracted to OMG, to understand the processes that drive the loss of Greenland ice.

“Not long ago, we wondered about the effect on sea levels if Earth’s major glaciers in the polar regions were to start retreating”, Rignot noted.

“The downward slope combined with warming ocean temperatures is what seems to be causing the acceleration now and why we predict it will continue to accelerate over the next few decades”, Paden said. Scientists used laser-profiling systems, sensitive radar sounder, optical images from space, and gravimeter to measure changes in the size, shape, and position of Greenland’s glacial ice.

Until now, the northern part of Greenland was not thought to be losing ice in significant quantities but this latest research finds that large-scale melting has now spread to all parts of the country, he added.