The following is pulled from the University Corporation for Atmospheric Research press release:
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.”
Source: University Corporation for Atmospheric Research
Image Source: NASA Goddard Space Flight Center