for National Geographic News
This year's cooler-than-expected summer means the Arctic probably won't experience ice-free summers until 2030 or 2040, scientists say.
Some models had previously predicted that the Arctic could be ice free in summer by as soon as 2013, due to rising temperatures from global warming.
However, that scenario required Arctic sea ice to shrink at the record-setting pace of summer 2007, when sea ice coverage dropped to 1.6 million square miles (4.13 million square kilometers), said Walter Meier, a scientist at the U.S. National Snow and Ice Data Center in Boulder, Colorado.
This summer Arctic sea ice shrank to only 1.97 million square miles (5.1 million square kilometers). The 2009 drop is still the third largest on record, but it's not as big as some scientists had feared. (Explore a vanishing sea-ice interactive.)
Arctic sea ice typically shrinks in the summer and grows in the winter. It typically reaches its lowest coverage around mid-September.
Meier cautions the new findings do not mean the Arctic is in recovery, or that global warming is slowing down.
"I look at it as a one-year reprieve," he said. "I don't expect that to continue."
For one thing, this year's ice is thinner than in the past, and thus more vulnerable to future melt.
"If we get another really warm summer," Meier said, "we'll probably be back to where we were in 2007."
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