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|a Melt-induced speed-up of Greenland ice sheet offset by efficient subglacial drainage |h [electronic resource]. |
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|a [S.l.] : |b Macmillan Publishers Limited, |c 2011. |
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|a Nature Magazine Volume 469. |
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|a Please contact the owning institution for licensing and permissions. It is the user's responsibility to ensure use does not violate any third party rights. |
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|a Fluctuations in surface melting are known to affect the speed of
glaciers and ice sheets, but their impact on the Greenland ice
sheet in a warming climate remains uncertain. Although some
studies suggest that greater melting produces greater ice-sheet
acceleration, others have identified a long-term decrease in
Greenland’s flow despite increased melting. Here we use satellite
observations of ice motion recorded in a land-terminating sector of
southwest Greenland to investigate the manner in which ice flow
develops during years of markedly different melting. Although
peak rates of ice speed-up are positively correlated with the degree
of melting, mean summer flow rates are not, because glacier slowdown
occurs, on average, when a critical run-off threshold of about
1.4 centimetres a day is exceeded. In contrast to the first half of
summer, when flow is similar in all years, speed-up during the
latter half is 62616 per cent less in warmer years. Consequently,
in warmer years, the period of fast ice flow is three times shorter
and, overall, summer ice flow is slower. This behaviour is at odds
with that expected frombasal lubrication alone7,9. Instead, itmirrors
that of mountain glaciers10–12, where melt-induced acceleration of
flow ceases during years of high melting once subglacial drainage
becomes efficient. A model of ice-sheet flow that captures switching
between cavity and channel drainage modes is consistent with the
run-off threshold, fast-flow periods, and later-summer speeds we
have observed. Simulations of the Greenland ice-sheet flow under
climate warming scenarios should account for the dynamic evolution
of subglacial drainage; a simplemodel of basal lubrication alone
misses key aspects of the ice sheet’s response to climate warming. |
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|a Electronic reproduction. |c Florida International University, |d 2015. |f (dpSobek) |n Mode of access: World Wide Web. |n System requirements: Internet connectivity; Web browser software. |
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|a dpSobek |c Sea Level Rise |
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|u http://dpanther.fiu.edu/dpService/dpPurlService/purl/FI15062078/00001 |y Click here for full text |
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|a http://dpanther.fiu.edu/sobek/content/FI/15/06/20/78/00001/FI15062078_thm.jpg |
