. Earth Science News .

Arctic ice melt could pause then resume
by Staff Writers
Boulder CO (SPX) Aug 17, 2011

To simulate what is happening with the ice, the NCAR team used a newly updated version of one of the world's most powerful computer climate models. The software, known as the Community Climate System Model, was developed at NCAR in collaboration with scientists at multiple organizations and with funding by NSF and the Department of Energy.

Although Arctic sea ice appears fated to melt away as the climate continues to warm, the ice may temporarily stabilize or somewhat expand at times over the next few decades, new research indicates.

The computer modeling study, by scientists at the National Center for Atmospheric Research, reinforces previous findings by other research teams that the level of Arctic sea ice loss observed in recent decades cannot be explained by natural causes alone, and that the ice will eventually disappear during summer if climate change continues.

But in an unexpected new result, the NCAR research team found that Arctic ice under current climate conditions is as likely to expand as it is to contract for periods of up to about a decade.

"One of the results that surprised us all was the number of computer simulations that indicated a temporary halt to the loss of the ice," says NCAR scientist Jennifer Kay, the lead author. \

"The computer simulations suggest that we could see a 10-year period of stable ice or even a slight increase in the extent of the ice. Even though the observed ice loss has accelerated over the last decade, the fate of sea ice over the next decade depends not only on human activity but also on climate variability that cannot be predicted."

Kay explains that variations in atmospheric conditions such as wind patterns could, for example, temporarily halt the sea ice loss. Still, the ultimate fate of the ice in a warming world is clear.

"When you start looking at longer-term trends, 50 or 60 years, there's no escaping the loss of ice in the summer," Kay says.

Kay and her colleagues also ran computer simulations to answer a fundamental question: why did Arctic sea ice melt far more rapidly in the late 20th century than projected by computer models? By analyzing multiple realizations of the 20th century from a single climate model, they attribute approximately half the observed decline to human emissions of greenhouse gases, and the other half to climate variability.

These findings point to climate change and variability working together equally to accelerate the observed sea ice loss during the late 20th century.

The study appears this week in Geophysical Research Letters. It was funded by the National Science Foundation, NCAR's sponsor.

Rapid melt
Since accurate satellite measurements became available in 1979, the extent of summertime Arctic sea ice has shrunk by about one third. The ice returns each winter, but the extent shrank to a record low in September 2007 and is again extremely low this year, already setting a monthly record low for July.

Whereas scientists warned just a few years ago that the Arctic could lose its summertime ice cover by the end of the century, some research has indicated that Arctic summers could be largely ice-free within the next several decades.

To simulate what is happening with the ice, the NCAR team used a newly updated version of one of the world's most powerful computer climate models. The software, known as the Community Climate System Model, was developed at NCAR in collaboration with scientists at multiple organizations and with funding by NSF and the Department of Energy.

The research team first evaluated whether the model was a credible tool for the study. By comparing the computer results with Arctic observations, they verified that, though the model has certain biases, it can capture observed late 20th century sea ice trends and the observed thickness and seasonal variations in the extent of the ice.

Kay and her colleagues then conducted a series of future simulations that looked at how Arctic sea ice was affected both by natural conditions and by the increased level of greenhouse gases in the atmosphere. The computer studies indicated that the year-to-year and decade-to-decade trends in the extent of sea ice are likely to fluctuate increasingly as temperatures warm and the ice thins.

"Over periods up to a decade, both positive and negative trends become more pronounced in a warming world," says NCAR scientist Marika Holland, a co-author of the study.

The simulations also indicated that Arctic sea ice is equally likely to expand or contract over short time periods under the climate conditions of the late 20th and early 21st century.

Although the Community Climate System Model simulations provide new insights, the paper cautions that more modeling studies and longer-term observations are needed to better understand the impacts of climate change and weather variability on Arctic ice.

The authors note that it is also difficult to disentangle the variability of weather systems and sea ice patterns from the ongoing impacts of human emissions of greenhouse gases.

"The changing Arctic climate is complicating matters," Kay says. "We can't measure natural variability now because, when temperatures warm and the ice thins, the ice variability changes and is not entirely natural."

Interannual to multidecadal Arctic sea ice extent trends in a warming world - Jennifer Kay, Marika Holland, and Alexandra Jahn - Geophysical Research Letters

Related Links
Beyond the Ice Age

Get Our Free Newsletters Via Email
Buy Advertising Editorial Enquiries

. Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

Large variations in Arctic sea ice
Copenhagen, Denmark (SPX) Aug 09, 2011
For the last 10,000 years, summer sea ice in the Arctic Ocean has been far from constant. For several thousand years, there was much less sea ice in The Arctic Ocean - probably less than half of current amounts. This is indicated by new findings by the Danish National Research Foundation for Geogenetics at the University of Copenhagen. The results of the study will be published in the journal Sc ... read more

Fukushima contaminating China's seas?

Building booms in S.Lanka president's home town

Greenpeace hands Rainbow Warrior to Bangladesh

Disaster-hit Japan marks 66 years since WWII end

First quantitative measure of radiation leaked from Fukushima reactor

Shooting light a curve

Catalyst that makes hydrogen gas breaks speed record

Coffee stain helps smarter inks

Worldwide map identifies important coral reefs exposed to stress

Hydrogen highway in the deep sea

Banana peels purify contaminated water

Putin opens giant anti-flood dam in Saint Petersburg

Polar climate change may lead to ecological change

Arctic ice melt could pause then resume

The last 3 million years at a snail's pace

Large variations in Arctic sea ice

Rapid evolution within single crop-growing season increases insect pest numbers

Making a bee-line for the best rewards

UBC researchers discover key mechanism that regulates shape and growth of plants

New technology could capture ammonia from liquid manure

Pakistan floods make 60,000 homeless: officials

Tropical storm Greg forms with hurricane potential

Taiwan to use mobile radars against typhoons

Tropical Storm Gert forms in Atlantic

Top Zimbabwe military officer killed in blaze

Zimbabwe powerbroker, ex-defence chief Mujuru dies in blaze

AU troops find Shebab arms cache in Mogadishu

Somali businesses warily return to war-hit market

Narcissism may benefit the young, researchers report; but older adults? Not so much

Study: Some are born with math ability

Six Million Years of African Savanna

Forest or grassland: where did humans learn to walk?

Memory Foam Mattress Review
Newsletters :: SpaceDaily Express :: SpaceWar Express :: TerraDaily Express :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News

The content herein, unless otherwise known to be public domain, are Copyright 1995-2011 - Space Media Network. AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement