AGU Release No. 11–27
August 11, 2011
For Immediate Release

WASHINGTON—Despite the rapid retreat of Arctic sea ice in recent years, the ice may temporarily stabilize or somewhat expand at times over the next few decades, new research indicates.

A new computer modeling study 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 melt away during summer if the climate continues to warm.

But in an unexpected new result, the 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 Jennifer Kay, the lead author and a scientist at the National Center for Atmospheric Research (NCAR). “The computer simulations suggest that we could see a 10-year period of stable ice or even an 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.

The study was published today in the journal Geophysical Research Letters, a publication of the American Geophysical Union.

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.

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 team used a newly updated version of one of the world’s most powerful computer climate models, the Community Climate System Model.

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.”

This research was funded by the National Science Foundation.

Notes for Journalists

Journalists and public information officers (PIOs) of educational and scientific institutions who have registered with AGU can download a PDF copy of this paper.

Or, you may order a copy of the paper by emailing your request to Maria-José Viñas at mjvinas@agu.org. Please provide your name, the name of your publication, and your phone number. Neither the paper nor this press release are under embargo.

Title

“Interannual to multidecadal Arctic sea ice extent trends in a warming world”

Authors

Jennifer E. Kay, Marika M. Holland, and Alexandra Jahn
Climate and Global Dynamics Division, National Center for Atmospheric Research, Boulder, Colorado, USA.

Author contact

Jennifer Kay, NCAR Scientist, Tel. +1 (303) 497-1730, jenkay@ucar.edu

 

2 Responses to Arctic ice melt could pause in coming decades

  1. Phil M says:

    This is good for the planet & good for the arctic, but you can guess already how this card will be played over at WTFUWT.

    They are all over it if there is even a month of rise in ice mass. They have been strangely silent for months since we have seen ice loss close to 2007 & looking like it will pass it.

    But now since this news they have life breathed into the denial.

    erfiebob says:
    August 11, 2011 at 12:28 pm

    Oh, come on. They’re just padding their bets now. No matter what happens with sea ice, they’ll be able to say “See we told you so global warming will still kill us all!”
    Moira says:
    August 11, 2011 at 12:33 pm

    Ice cycles.
    Chris says:
    August 11, 2011 at 12:33 pm

    Now that we are beginning to see probable cooling (apparently) from a reduction in solar activity. expect to see more and more of the models predict a pause in warming in order to claim they saw this coming and not to worry, warming is still going to occur, it’s just delayed.

    Handy way for them to try to keep the climate change money flowing in for another 10 years…
    Theo Goodwin says:
    August 11, 2011 at 12:34 pm

    Some of the Warmista have reached the bargaining stage.
    DJ says:
    August 11, 2011 at 12:38 pm

    ….In other words, research indicates that arctic ice could do anything, and we’ve got a weasel clause that will allow us to blame it all on anthropogenic forcing, right?

    http://wattsupwiththat.com/2011/08/11/from-ncar-an-unexpected-new-result-arctic-ice-likely-to-expand-as-it-is-to-contract/#more-44907

    • OveHG says:

      Yes, we’ll get a normal rubbish and misinformation from Watts, Bolt and other armchair experts and conspiracy theorists. Ho hum.

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