SOURCE: Washington Post
DATE: October 4, 2017
SNIP: Two new studies of Greenland, using sophisticated technologies and large scientific teams to pull together and process the data, have now gone further in taking the full measure of the island through that ever-so-basic scientific act: mapping.
The first, a comprehensive seabed mapping project, relying in part on new data from NASA’s OMG (“Oceans Melting Greenland”) mission, concludes that the Greenland ice sheet is far more exposed to the planet’s warming oceans than previously known — and has more ice to give up than, until now, has been recognized.
The new research finds that “between 30 and 100% more glaciers are potentially exposed to [warm Atlantic water] than suggested by previous mapping, which represents 55% of the ice sheet’s total drainage area.” In other words, more than half of Greenland’s ice lies in or flows through areas that could be influenced by warming seas.
Meanwhile, on Wednesday, a separate team of scientists used another quite different large-scale mapping exercise to document a surprising — but closely related — change in Greenland’s above-water topography. Publishing in the journal Nature, they showed that the contours of the huge island are changing because with all the ice melt rushing from glaciers to the sea, river deltas are expanding outward — a rare occurrence these days when deltas around the world are generally retreating, threatened by rising seas (think of the Mississippi River delta, for instance, and its vanishing wetlands).
“Over the period of the 1980s to 2010s, rapid increase of meltwater and sediment fluxes caused dramatic advance of these deltas into the ocean,” said Irina Overeem, one of the study’s authors and a researcher at the Institute of Arctic and Alpine Research at the University of Colorado at Boulder.
This delta expansion is not just a curiosity, Overeem explained, it’s a confirmation that Greenland has been losing more ice in the past few decades, awakening large flows of water from land to sea that carry sediment with them along the way.