Shock impacts hit Greenland’s ice
An aerial view of icebergs floating in Greenland’s Ilulissat Icefjord. Image: Mark Garten/UN Photo
LONDON, 14 May, 2016 – Seismic waves that race through Greenland’s bedrock may help answer questions about the pattern of melting and freezing over the Northern Hemisphere’s biggest single sheet of ice.
Scientists need answers because Greenland remains a puzzle: the glaciers may be accelerating their pace towards the sea − but, despite rising temperatures, the interior is not losing ice, according to a second study.
And a third study presents a new paradox: there may be little ice melt over most of the icecap, but changing climatic conditions suggest that less snow is falling.
There is enough ice packed on Greenland to raise global sea levels by seven metres if it melts. Right now, the flow from the island’s glaciers is probably pushing up sea levels by 0.6mm a year.
Harsh conditions
There is repeatedly confirmed evidence that glaciers are melting at an accelerating rate, and several consequences of global climate changethat suggest that this process should go on accelerating.
But research in Greenland’s harsh conditions is challenging, and year-round continuous observation so far has been almost impossible, even with airpower and satellite studies.
But German Prieto, assistant professor of geophysics in the department of Earth, atmospheric and planetary sciences at the Massachusetts Institute of Technology, and colleagues report in Science Advances journal that they could exploit the one source of evidence that would never falter.
The waves that crash on the coastline send tiny seismic shudders through the rock, and seismic wave velocity changes with rock density. So the reasoning is that changes in the mass of ice pressing down on the rocks could be revealed by changes in the speed of the waves through the rock.
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