World Atlas ice loss claim exaggerated: scientists | Reuters.
(Reuters) – The Times Atlas of the World exaggerated the rate of Greenland’s ice loss in its thirteenth edition last week, scientists said on Monday.
The atlas, published by HarperCollins, showed that Greenland lost 15 percent of its ice cover over the past 12 years, based on information from the National Snow and Ice Data Center in Colorado in the United States.
The Greenland ice sheet is the second biggest in the world and significant shrinking could lead to a global rise in sea levels.
“While global warming has played a role in this reduction, it is also as a result of the much more accurate data and in-depth research that is now available,” HarperCollins said on its website on Monday.
However, a number of scientists disputed the claim.
“We believe that the figure of a 15 percent decrease in permanent ice cover since the publication of the previous atlas 12 years (ago) is both incorrect and misleading,” said Poul Christoffersen, glaciologist at the Scott Polar Research Institute (SPRI) at the University of Cambridge.
“We concluded that a sizable portion of the area mapped as ice-free in the Atlas is clearly still ice-covered.”
Other scientists agreed.
“These new maps are ridiculously off base, way exaggerated relative to the reality of rapid change in Greenland,” said Jeffrey S. Kargel, senior research scientist at the University of Arizona.
The Times Atlas suggested the Greenland ice sheet has lost 300,000 square kilometers in the past 12 years, at a rate of 1.5 percent per year.
However, measurements suggest this rate is at least 10 times faster than in reality, added J. Graham Cogley, Professor of Geography at Trent University, Ontario, Canada.
“It could easily be 20 times too fast and might well be 50 times too fast,” he added.
Last year, a U.N. committee of climate scientists came under fire for bungling a forecast of when Himalayan glaciers would thaw.
The panel’s 2007 report, the main guide for governments in fighting climate change, included an incorrect projection that all Himalayan glaciers could vanish by 2035, hundreds of years earlier than scientists’ projections.
(Reuters) – Arctic sea ice this summer melted to a record low extent or will come a close second, two different research institutes said on Tuesday, confirming a trend which could yield an ice-free summer within a decade.
The five biggest melts in a 32-year satellite record have all happened in the past five years, likely a result of both manmade climate change and natural weather patterns.
One impact of an ice-free summer may be disrupted world weather, with hints already as some scientists blame recent chill winters in Europe and North America on warmer, open Arctic seas diverting polar winds south.
Researchers at the University of Bremen in Germany say that this year has already toppled 2007 after sea ice retreated to a record low on September 8.
The U.S.-based National Snow and Ice Data Center (NSIDC) says this year is number two with the melt season all but over before winter returns to the high Arctic.
“I’m increasingly confident it will remain number two,” said Mark Serreze, head of the NSIDC. But the result may be close enough to declare a tie, he added.
Most important than the record was the trend, said University of Bremen’s Georg Heygsterall, referring to how the years since 2007 had all since bigger summer melts than those before.
A tie would echo the World Meteorological Organization’s view on recent rising global temperatures, after it declared 2010 a tie with 1998 and 2005 for the hottest year since such records began about a century and a half ago.
Bremen and NSIDC use satellites to measure microwave radiation from the ice pack, but with slightly different methods: NSIDC can achieve a sharper image, but Bremen to a higher resolution of 6 kilometers compared with 25 km.
Researchers agree that summer sea ice is disappearing faster than expected.
“An ‘ice-free’ summer Arctic is rapidly on its way. Most data indicate that the models are underestimating the rate of ice-loss,” said Kim Holmen, research director at the Norwegian Polar Institute.
“That means that we see more rapid change than the model scenarios have suggested. It also means that there are processes out there that influence ice that we have yet to understand.”
The summer ice retreat has already reached levels which were forecast three decades from now in models used in the U.N. climate panel’s flagship report four years ago.
The Intergovernmental Panel on Climate Change (IPCC) used models which forecasted an ice-free summer at the end of this century.
But that could happen as early as 2013, according to one of the most aggressive estimates. Other experts predict an ice-free Arctic Ocean in summer anywhere from 2020-2050.
“I still see a high likelihood of a near ice-free Arctic Ocean during summer around 2016, plus or minus three years,” said Wieslaw Maslowski at the California-based Naval Postgraduate School.
More difficult to measure than area is ice thickness, which is also diminishing, most scientists agree.
Researchers at the University of Washington in Seattle calculated ice volume, combining area and thickness, reached a record low last year and would do so again this year.
(Reporting by Gerard Wynn)
More on Sea-Ice loss:
<span class="articleLocation”>(Reuters) – Sea ice on the Arctic Ocean shrank to its second-smallest extent since modern records began, in keeping with a long-term trend, the U.S. National Snow and Ice Data Center reported on Thursday.
The annual sea ice minimum was reached on September 9, the center said on its website here in a preliminary finding.
“Changing winds could still push ice flows together reducing ice extend further,” the researchers said. A full analysis will be available in October, when monthly data are available for all of September, which is usually the month when the annual minimum is reached.
Arctic Sea ice is an important sign of a changing climate, and what happens in the Arctic has a major influence on global weather patterns.
At its apparent minimum, sea ice around the North Pole covered 1.67 million square miles (4.33 million square km). That measurement is 61,800 square miles (160,000 square km) above the all-time record low reached in 2007, the center said.
However, it is far below the average minimum for the period 1979 through 2000, according to NSIDC. The satellite record began in 1979.
These figures differ from those reported by the University of Bremen in German, which issued a statement that the Arctic ice reached a record low minimum on September 8.
PATCHES OF WATER AMID THE ICE
Both the University of Bremen and NSIDC use microwave sensors to observe Arctic ice, but these sensors are on different satellites. The Bremen report uses images with higher spatial resolution, according to Walter Meier of NSIDC.
“They can see in more detail, they can see these little patches of water, whereas we see these areas as just ice covered,” Meier said by telephone. He said there can be higher potential for error with these high-resolution images, though there is no evidence of error in this case.
NSIDC’s records go back to 1979; the records used by Bremen go back to 2003. Both indicate the last five years were the least icy in the Arctic sea ice satellite record.
It’s not surprising that this year has not eclipsed the record year of 2007, Meier said.
That year was “a perfect storm” of ice-melting conditions in the Arctic, he said: warmer and sunnier than usual, with extremely warm ocean water and winds all acting in concert.
The fact that 2011 has seen the second-lowest ice extent without these extreme conditions shows a change in the character of the ice cover, Meier said.
Back in 2007, the ice was a consolidated mass which melted from the edges. This year, he said, the ice is more dispersed and the area is dominated by seasonal ice cover — less hardy than multi-year ice — which is more prone to melt.
“Now it doesn’t take as extreme of weather conditions to get to the 2007 ballpark,” Meier said.
(Reporting by Deborah Zabarenko in Washington, Editing by Cynthia Osterman)