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Arctic sea ice nears annual summer minimum

By Doyle Rice
USA TODAY

Sea ice in the Arctic will reach its annual minimum “any day now,” says Mark Serreze, director of the National Snow and Ice Data Center, which tracks Arctic ice.

Although not nearly as ice-free as last September’s all-time record low, the amount of Arctic sea ice in the summer of 2013 was well below average, and will likely go in the books as the sixth-smallest “extent” of Arctic sea ice on record, he says.

Sea ice is frozen ocean water that melts each summer and then refreezes each winter. It typically reaches its smallest “extent” in September and largest in March of each year.

The data center reported Wednesday that the extent of Arctic sea ice shrank to 1.98 million square miles on Tuesday. Last year, at its smallest point, the amount of sea ice shrank to 1.32 million square miles.

The average minimum Arctic ice extent each summer, based on data from 1979 to 2010, is about 2.37 million square miles.

Does the larger ice extent this summer mean that the world is cooling, as some people skeptical of climate change have claimed in the past few days as the Arctic nears its annual minimum? Absolutely not, reports Serreze, who says that there will be ups and downs in summer ice extent each year due to natural variability in climate and weather patterns.

He adds that the seven summers with the lowest amount of ice have all been in the past seven years. “The overall trend is downward, and it will continue to do so,” Serreze says.

The amount of summer sea ice in the Arctic has been steadily shrinking over the past few decades, due to man-made global warming, according to the National Oceanic and Atmospheric Administration.

“These contrasts in ice extent from one year to the next highlight the year-to-year variability attending the overall, long-term decline in sea ice extent,” according to an online report from the ice data center, which is located in Boulder, Colo.

Overall, since satellite-based measurements began in the late 1970s, Arctic sea ice extent has decreased in all months and virtually all regions. The Arctic continues to warm at about twice the rate compared with lower latitudes.

“The Arctic will be ice-free in the summer in a few decades,” Serreze says. “All we’ll have is winter ice.”

© 2013 USA TODAY. All rights reserved.

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