September 24, 2011

Greenland Melt Controversy

The two maps above are snapshots taken by The Guardian from The Times Comprehensive Atlas of the World. The one on the left is from the 1999 10th edition; on the right is the 2011 13th edition, just published by HarperCollins (whose owner is the Fox-laden and scandal-ridden News Corporation, headed by Rupert Murdoch). The new map shows Greenland having lost around 15% of its ice cover since 1999. The claims have caused an uproar among climate scientists, who insist that the actual loss of ice cover is much less than 1%.

From John Vidal of The Guardian:

[S]even researchers at Cambridge University's Scott Polar Research Institute backed by glaciologists in the US, Europe and elsewhere, have said that both the maps and the figure of 15% are wrong.

In a letter to the editors of the Times Atlas they agree that the Greenland ice cover is reducing but at nowhere near the extent claimed in the book. "A 15% decrease in permanent ice cover since the publication of the previous atlas 12 years ago is both incorrect and misleading.

"Numerous glaciers have retreated over the last decade. Because of this retreat, many glaciers are now flowing faster and terrain previously ice-covered is emerging along the coast – but not at the rate suggested. Recent satellite images of Greenland make it clear that there are in fact still numerous glaciers and permanent ice cover where the new Times Atlas shows ice-free conditions and the emergence of new lands."

According to the researchers, the volume of ice contained in the Greenland ice sheet is approximately 2.9m cubic kilometres and the current rate whereby ice is lost is roughly 200 cubic kilometres per year – a decrease of about 0.1% by volume over 12 years.

Other researchers backed the Scott team. "Although many of these regions have decreased in area and thickness over the past decade(s), reported in many recent scientific papers, the misinterpretation of enormous losses of glacierised area from these maps is far off the range in measured losses," said Hester Jiskoot, a glaciologist at the University of Lethbridge in Alberta.

"A number like 15% ice loss used for advertising the book is simply a killer mistake that cannot be winked away," said Jeffrey Kargel, a senior researcher at the University of Arizona.

Several researchers said the atlas's authors may have confused ice thickness with ice extent, defining the ice sheet margin at 500m high (the contour) and colouring brown and pink anything below 500m. "They [seem to] show the contour as ice thickness, colouring in everything white that is above 500m. They appear to have missed out the edge of the ice sheet," said Ian Willis, researcher at the Scott institute.

A spokeswoman for Times Atlas defended the 15% figure and the new map. "We are the best there is. We are confident of the data we have used and of the cartography. We use data supplied by the US Snow and Ice Data Centre (NSIDC) in Boulder, Colorado. They use radar techniques to measure the permanent ice. We have compared the extent of the ice surface in 1999 with that of 2011. Our data shows that it has reduced by 15%. That's categorical," she said.

The amusing feature of this controversy is how it makes a hash of the broader ideological alignments, with an arm of the climate-change-denying News Corp making wild claims that would make Al Gore blush. In this vein, one recalls that the first great world leader to draw attention to the danger of global warming was none other than Ronald Reagan's best friend, Margaret Thatcher, who was not renowned as a statist. In a speech in 1988 to the Royal Society, at Fishmonger's Hall in London, the then Prime Minister declared:

For generations, we have assumed that the efforts of mankind would leave the fundamental equilibrium of the world's systems and atmosphere stable. But it is possible that with all these enormous changes (population, agricultural, use of fossil fuels) concentrated into such a short period of time, we have unwittingly begun a massive experiment with the system of this planet itself. 

Recently three changes in atmospheric chemistry have become familiar subjects of concern. The first is the increase in the greenhouse gases—carbon dioxide, methane, and chlorofluorocarbons—which has led some to fear that we are creating a global heat trap which could lead to climatic instability. We are told that a warming effect of 1°C per decade would greatly exceed the capacity of our natural habitat to cope. Such warming could cause accelerated melting of glacial ice and a consequent increase in the sea level of several feet over the next century.

Mrs. Thatcher subsequently recanted her views and threw in with the climate skeptics. One admirer of Thatcher asks, not unreasonably, whether her fuss about global warming was "really just a cynical ploy . . . to help crush Britain's coal miners while bigging up the nuclear power industry in order to bolster her Trident programme?" Among the handful of climate skeptics on Britain's left, such as Alexander Cockburn, such was always the great suspicion.

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