The Arctic's summer ice coverage could hold its ground or even bounce back slightly, even as global average temperatures rise. But like a Guns 'n' Roses tour, the comeback will be short lived and eventually doomed to disappear. A computer climate model created by the National Center for Atmospheric Research (NCAR) found that in some of the runs of the simulation, Arctic summer sea ice actually halted its retreat or even expanded for a decade or so. But in the long run, climate change won out and most of the summer ice melted away completely within 50 to 60 years.
“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,” said NCAR scientist Jennifer Kay, the lead author of the research, which was recently published in Geophysical Research Letters. The National Science Foundation funded the study.
“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,” said Kay.
The Earth's climate has always been a complex system influenced by many factors. The effects of human activities make the system even more complex and harder to predict. That is part of the reason why no computer simulation ever returns the same results for every run of the program.
“The changing Arctic climate is complicating matters,” Kay said. “We can’t measure natural variability now, because when temperatures warm and the ice thins, the ice variability changes and is not entirely natural.”
To look at the short and long term trends, the scientists used the recent version of the most powerful climate modeling software in the world, the Community Climate System Model.
Accuracy of future predictions was checked by running simulations of the late 20th century. The Model replicated the events of the past well enough to suggest that its forecasts of possible futures are realistic.
The simulations may say a comeback is possible, but reality shows it won't be this year. July 2011 set a monthly record for minimum sea ice extent, according to the National Snow and Ice Data Center.
“When you start looking at longer-term trends, 50 or 60 years, there’s no escaping the loss of ice in the summer,” Kay said.
IMAGE 1: Melt water collecting in ponds on the surface of Arctic ice. The darker coloration absorbs more heat and causes further melting. (NASA, July 12, 2011)
IMAGE 2: This map and graph show that Artic ice is melting for longer periods of time each year. (NASA, Wikimedia Commons)
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