NASA Study Explains Why Greenland Glaciers Are Melting At Radically Different Rates

Posted: Jun 23 2018, 8:59am CDT | by , Updated: Jun 23 2018, 9:59am CDT, in Latest Science News


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NASA Study Explains Why Greenland Glaciers are Melting at Radically Different Rates
Credit: NASA

NASA's OMG campaign reveals a plume of warm water flowing up the undersides of glacier Tracy

Greenland has lost billions of tons of ice in the past century. However, the melting is not consistent over the entire area. Observations reveal that some glaciers are disappearing faster than the others. For instance, two prominent glaciers in the region Tracy and Heilprin are melting at radically different rates. They are the largest glaciers in Inglefield Gulf in northwest Greenland and have retreated significantly in the 21st century due to atmospheric warming but their rates of retreat diverged dramatically.

Using ocean data from NASA's Oceans Melting Greenland (OMG) campaign, researchers surveyed ocean and ice conditions beneath glaciers in southeast Greenland and gained a much better understanding of their varied vulnerability to melting. Based on data, researchers have found a plume of warm water flowing up Tracy's undersides while a much colder plume is detected in front of Heilprin. It may help explain why Tracy is more vulnerable to melting from below and why Heilprin is not thinning or retreating as quickly.

Tracy and Heilprin glaciers were first observed in 1892 and have been measured occasionally ever since. Even though these glaciers lie side by side and experience same conditions, Tracy has retreated more than 9.5 miles in 125 years. That is almost four times the rate of retreat at Heilprin, which lost less than 2.5 miles over the same span.

To solve this mystery, NASA designed Oceans Melting Greenland (OMG) campaign. The five-year campaign involves an airborne survey to quantify ice loss from all glaciers that drain the Greenland Ice Sheet. The seafloor topography was also mapped by using boat-based measurements.

A previous NASA campaign called Operation IceBridge already documented a major difference between these glaciers. According to its findings, Tracy is placed on bedrock at a depth of about 2,000 feet below the ocean surface, while Heilprin extends only 1,100 feet beneath the waves.

“Scientists would expect this difference to affect the melt rates because the top ocean layer around Greenland is colder than the deep water, which has traveled north from the midlatitudes in ocean currents. The warm water layer starts about 660 feet (200 meters) down from the surface, and the deeper the water, the warmer it is. Naturally, a deeper glacier would be exposed to more of this warm water than a shallower glacier would.” NASA statement said.

OMG boat measurements showed a river of meltwater draining out from under Tracy. As the warm, salty water reaches the undersides of the glacier, it fuels its increasingly rapid retreat.

OMG Principal Investigator Josh Willis says. "In fact, quite a lot of warm water comes in from offshore, mixes with the shallower layers and comes over the sill."

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<a href="/latest_stories/all/all/47" rel="author">Hira Bashir</a>
The latest discoveries in science are the passion of Hira Bashir (). With years of experience, she is able to spot the most interesting new achievements of scientists around the world and cover them in easy to understand reporting.




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