Temperatures in the Arctic last fall hit record highs, an international team of scientists reported Thursday. According to the authors of the annual Arctic Report Card, temperatures were more than 9 degrees Fahrenheit above normal and are predicted to remain nearly as high this year.
“The year 2007 was the warmest year on record in the Arctic,” said Jackie Richter-Menge, a climate expert at the Cold Regions Research and Engineering Laboratory in Hanover, N.H, and editor of the latest Arctic Report Card.
The material presented in the paper is peer-reviewed by topical experts of the Climate Experts Group of the Arctic Council.
The most recent numbers continue a general Arctic-wide warming trend that began in the mid-1960s. Warmer than normal temperatures are due largely to the major loss of sea ice in recent years which allows more solar heating of the ocean. The summers of 2005 through 2007 all ended with extensive areas of open water. This allowed extra heat to be absorbed by the ocean from solar radiation, resulting in an ice freeze-up that occurred later than usual.
Authors of the report stress that all of the arctic warming is not attributable to global warming. “Global warming by itself wouldn’t cause this much sea ice loss,” said James Overland, an Arctic expert at the Pacific Marine Environmental Laboratory in Seattle. Nor would changes in wind and ocean currents alone.
And although the Arctic is warming overall, its effects vary from place to place. The Bering Sea, for example, is in a cooling spell, and an unusually severe winter has bulked up Alaska’s glaciers.
One thing is clear, all of this warming cannot be undone quickly.
“There has been a massive loss of sea ice starting in the 1990s,” said one of the authors, James Overland, an “In 2008, we’ve lost so much multi-year old ice, it’s very difficult for the ice cover to go back to where it was 20 years ago.”
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