James Overland of NOAA's Pacific Marine Environmental Laboratory and Muyin Wang of the NOAA Joint Institute for the Study of Atmosphere and Ocean at the University of Washington, looked at three methods of predicting when the Arctic will be nearly ice free in the summer.
"There is no one perfect way to predict summer sea ice loss in the Arctic," said Wang. "So we looked at three approaches that result in widely different dates, but all three suggest nearly sea ice-free summers in the Arctic before the middle of this century."
Note: Overland and Wang emphasized that the term "nearly" ice free is important as some sea ice is expected to remain north of the Canadian Archipelago and Greenland.
"Some people may interpret this to mean that models are not useful. Quite the opposite," said Overland. "Models are based on chemical and physical climate processes and we need better models for the Arctic as the importance of that region continues to grow."
Taken together, the range among the multiple approaches still suggests that it is very likely that the timing for future sea ice loss will be within the first half of the 21st century, with a possibility of major loss within a decade or two.
"Rapid Arctic sea ice loss is probably the most visible indicator of global climate change; it leads to shifts in ecosystems and economic access, and potentially impacts weather throughout the northern hemisphere," said Overland. "Increased physical understanding of rapid Arctic climate shifts and improved models are needed that give a more detailed picture and timing of what to expect so we can better prepare and adapt to such changes. Early loss of Arctic sea ice gives immediacy to the issue of climate change."
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