[font face=Serif][font size=5]Rainfall drives rapid melt and flow of the Greenland ice sheet[/font]

13 July 2015 Aberystwyth University

[font size=3]According to a new study published in Nature Geoscience, the Greenland ice sheet has been shown to accelerate in response to surface rainfall and melt associated with late-summer and autumnal cyclonic weather events.

Samuel Doyle and an international team of colleagues led from Aberystwyth University’s Centre for Glaciology combined records of ice motion, water pressure at the ice sheet bed, and river discharge with surface meteorology across the western margin of the Greenland ice sheet and captured the wide-scale effects of an unusual week of warm, wet weather in late August and early September, 2011.

They found that the cyclonic weather system led to extreme surface runoff – a combination of ice melt and rain – that overwhelmed the ice sheet’s basal drainage system, driving a marked increase in ice flow across the entire western sector of the ice sheet and extending 140 km into the ice sheet’s interior.

“It is like an urban sewerage system that is temporarily overwhelmed by an intense rain-storm. The ice sheet plumbing – literally a network of pipes, cavities and channels – gets backed up by the sheer quantity of runoff draining into it, leading to flooding and high water pressures, which literally hydraulically lifts the ice sheet up off its bed, reducing basal friction and sending it on its way”, said Prof Alun Hubbard the principal investigator who led the 4-year project which was funded by Natural Environment Research Council (NERC) and the Royal Geographical Society amongst others.

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