Feeds

Greenland ice loss rates 'one-third' of what was thought

New results 'deviate sharply' from established wisdom

New hybrid storage solutions

The rate at which ice is disappearing from Greenland and Western Antarctica has been seriously overestimated, according to new research.

Contrasting estimates of Greenland ice melt. Previous analysis in blue: New in red. The colour bands represent uncertainty. Credit: Nature Geoscience

'Deviates rather sharply from general assumptions' - Yes.

Measuring a disappearing ice cap is actually quite difficult to do, as the areas in question are remote, hostile environments and the exact depth of ice is often unknown. This has caused a lot of argument among climate scientists regarding how much ice is melting and running into the sea, as this affects predictions of sea-level rise and other aspects of climate modelling. (Floating sea ice, like that which makes up most of the Arctic cap apart from Greenland, is less of an issue as its melting doesn't affect the sea level.)

Thus it is that since 2002, NASA's Gravity Recovery and Climate Experiment (GRACE) satellite data has been used to make an estimate of ice melt from Greenland and Western Antarctica. (The rest of Antarctica doesn't seem to be melting at all - indeed Antarctica as a whole is actually gaining ice area rather than losing it - but some regions in the West are melting. The reasons for this are under investigation.)

The original GRACE-based estimates indicated as much as 1,500 billion tonnes ice loss just from Greenland in the period 2003-2009 - equivalent to a global sea-level rise of over 4mm on its own. However it has since become clear that these numbers weren't properly corrected for the phenomenon of "rebound", where the Earth's crust rises as ice is removed. GPS precise-location devices fixed to bedrock outcrops in Antarctica showed this last year, but nobody was sure how bad the errors were.

Now a team of researchers based at NASA's Jet Propulsion Laboratory and in the Netherlands say they have the answer.

"The corrections for deformations of the Earth’s crust have a considerable effect on the amount of ice that is estimated to be melting each year," explains Dr Bert Vermeersen. "We have concluded that the Greenland and West Antarctica ice caps are melting at approximately half the speed originally predicted."

Vermeersen and his colleagues' calculations show that as little as 500 gigatonnes of ice or even less could have melted from Greenland during 2003-2009, translating into less than 2mm of sea-level rise. In the case of Greenland, it could be that the current estimates are triple what they should be.

"For Greenland in particular, we have found a glacial isostatic adjustment model that deviates rather sharply from general assumptions," says Vermeersen.

Both the JPL/Dutch team and other boffins examining the work caution that more GPS locators need to be attached to the bedrock in order to refine the results.

For those who'd like to know more, a statement issued yesterday by Vermeersen's university is here. The new research can be read here by subscribers to Nature Geoscience, and analysis of it by independent expert boffins likewise here. ®

Secure remote control for conventional and virtual desktops

More from The Register

next story
Thought that last dinosaur was BIG? This one's bloody ENORMOUS
Weighed several adult elephants, contend boffins
Boffins say they've got Lithium batteries the wrong way around
Surprises at the nano-scale mean our ideas about how they charge could be all wrong
Chelyabinsk-sized SURPRISE asteroid to skim Earth, satnav birds
Space rock appears out of nowhere, buzzes planet on Sunday
City hidden beneath England's Stonehenge had HUMAN ABATTOIR. And a pub
Boozed-up ancients drank beer before tearing corpses apart
'Duck face' selfie in SPAAAACE: Rosetta's snap with bird comet
Probe prepares to make first landing on fast-moving rock
Archaeologists and robots on hunt for more Antikythera pieces
How much of the world's oldest computer can they find?
prev story

Whitepapers

Providing a secure and efficient Helpdesk
A single remote control platform for user support is be key to providing an efficient helpdesk. Retain full control over the way in which screen and keystroke data is transmitted.
Top 5 reasons to deploy VMware with Tegile
Data demand and the rise of virtualization is challenging IT teams to deliver storage performance, scalability and capacity that can keep up, while maximizing efficiency.
Reg Reader Research: SaaS based Email and Office Productivity Tools
Read this Reg reader report which provides advice and guidance for SMBs towards the use of SaaS based email and Office productivity tools.
Security for virtualized datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.
Secure remote control for conventional and virtual desktops
Balancing user privacy and privileged access, in accordance with compliance frameworks and legislation. Evaluating any potential remote control choice.