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article imageNASA's OMG campaign reveals bad news for Greenland glaciers

By Karen Graham     Nov 3, 2017 in Environment
New, accurate and comprehensive high-resolution maps of Greenland's bedrock and coastal seafloor show that the country is actually — physically — shrinking due to climate change, and it’s happening at a much quicker pace than scientists once thought
On November 1, 2017, in the journal Geophysical Research Letters, a team of NASA and University of California Irvine researchers, together with collaborators from over 30 institutions published the most comprehensive, accurate and high-resolution relief maps ever made of Greenland's bedrock and coastal seafloor.
NASA's five-year Oceans Melting Greenland (OMG) mission was launched in 2015 with the express purpose of studying exactly how fast warm ocean waters are melting Greenland's glaciers from below.
Glacier Canyons in NW Greenland.
IceBridge Mission  May  2017.
Glacier Canyons in NW Greenland. IceBridge Mission, May, 2017.
Besides gathering information on water temperature fluctuations on the continental shelf that surrounds Greenland, scientists are learning how marine glaciers react to the presence of warm, salty Atlantic Water. And because of the complicated geometry of the seafloor, currents are able to steer the warmer waters into the long, narrow and pristine fjords where the warmer currents interact with coastal glaciers.
In June 2017, Digital Journal reported on a study published online, documenting evidence of waves rippling through Greenland's Rink Glacier, an outlet glacier to the sea on the island's west coast. The NASA Jet Propulsion Laboratory study also found that meltwater loss was extensive. This study prompted further detailed studies that were released this week.
The technical instruments used in OMG mission and study
The study used NASA's P-3 Orion, outfitted with some high-tech instrumentation this year, including a scanning laser altimeter that measures surface elevation, three types of radar systems to study ice layers and the bedrock underneath the ice sheet, a high-resolution camera to create color maps of polar ice, and infrared cameras to measure surface temperatures of sea and land ice.
The diagram represents a typical glacier in Greenland. Below the cold  fresh layer near the surface ...
The diagram represents a typical glacier in Greenland. Below the cold, fresh layer near the surface a layer of warm, salty water reaches into the fjords to melt the glacier's edge. OMG will measure the volume and extent of this warm layer each year and relate it to thinning and retreat of the glaciers.
Additionally, the research included new ocean bathymetry data from 30 different sources, in combination with the mass conservation method to produce a detailed, seamless, and comprehensive map of the bed topography and fjord bathymetry around the entire periphery of Greenland, up to within 50 kilometers of the coast at a horizontal spatial resolution of up to 150 meters. In poorly charted fjords, the scientists relied on synthetic fjord bathymetries.
What the latest OMG Mission found is disturbing
The new maps presented through the study show that two to four times more oceanfront glaciers in Greenland extend deeper than 200 meters (656 feet) below sea level than previously thought. This is particularly bad because the top 182 meters (597 feet) of water around Greenland is colder Arctic waters.
Left: Greenland topography color coded color-coded from 4 900 feet (1 500 meters) below sea level (d...
Left: Greenland topography color coded color-coded from 4,900 feet (1,500 meters) below sea level (dark blue) to 4,900 feet above (brown). Right: Regions below sea level connected to the ocean; darker colors are deeper. The thin white line shows the current extent of the ice sheet. Credit: UCI.
But below that colder surface water is the warmer Atlantic waters that come from further south. This deep water can be as much as 3 to 4 degrees Celsius warmer than the colder Arctic waters. Deeper-seated glaciers exposed to this warmer water cause them to melt more rapidly.
The researchers were also able to use the new maps to redefine their estimate of Greenland's total volume of ice and its potential to add to global sea level rise if the ice were to melt completely. While it may take 200 to 300 years for that to happen, it would raise sea levels around the globe about 7.42 meters (24.24 feet).
More about Greenland, coastal ice, new mapping, Satellite imagery, Topography Interferometer
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