Guest post by David Middleton
From Live Science…
Records Melt Away on Greenland Ice Sheet
By Brett Israel, OurAmazingPlanet Staff Writer posted: 21 January 2011
The disappearing Greenland Ice Sheet set several records during an unusually long melt last year, according to a new study.
Running from April to mid-September, the melt season of 2010 was about a month longer than usual, said study team member Jason Box, a geographer and climatologist at Ohio State University.
“The disappearing Greenland Ice Sheet”… Where in the heck did the author get the idea that the Greenland Ice Sheet was disappearing?
Greenland Ice Sheet Isopach Map (Wikipedia)
A recent publication by a team from TU Delft & JPL found that the Greenland ice sheet was melting at half the rate previously thought. They estimate that the Greenland ice sheet is losing ~230 gigatonnes (Gt) of ice per year. One Gt of water has a volume of 1 cubic km (km^3). 1 Gt of ice has a larger volume than 1 Gt of water… But, for the purpose of this exercise, we’ll assume 1 Gt of ice has a volume of 1 km^3.
If 1 Gt of ice has a volume of 1 km^3 and the current volume of the Greenland ice sheet is ~5 million km^3 and Greenland continues to melt at a rate of 230 km^3/yr over the next 90 years… The Greenland ice sheet will lose a bit more than 0.4% of its ice volume.~230 gigatonnes (Gt) of ice per year equates to about 0.005% of ice mass loss per year. At the current rate, it would take 1,000 years for the Greenland Ice Sheet to lose 5% of its volume.
The Earth’s climate was at least 2°C warmer during the Holocene Climatic Optimum and the Greenland Ice Sheet did not melt, disappear or destabilize…
The Earth’s climate was at least 2°C warmer and the Arctic was about 5°C warmer than it currently is during the Sangamonian (Eemian) interglacial. and the Greenland Ice Sheet did not melt, disappear or destabilize.
Greenland’s glaciation began during the Miocene, when the Earth’s climate was at least 5°C warmer than it currently is. It advanced rapidly after the Mid-Pliocene Warm Period.
Earth’s climate would have to warm back up to where it was in the mid-Miocene (~15 MYA) in order to destabilize the Greenland ice sheet…
Cenozoic Climate H/T Bill Illis
There is no scientific evidence to back up the assertion of a “disappearing Greenland Ice Sheet. For a detailed explanation as to why the Greenland ice sheet cannot collapse under any AGW scenario, see Ollier & Pain, 2009.