2007 will go in the record books as the second-warmest year recorded in a century, according to a new NASA analysis.
The global temperature equaled 1998, and was just behind 2005. The eight warmest years recorded have all occurred since 1998, and the 14 warmest years in the record have all occurred since 1990.
2007 also saw record melting of Arctic sea ice, and the exceptional Arctic temperatures drove the global average, NASA said. That trend is worrying because ice reflects light and heat that is absorbed when darker water is exposed by melting. There is concern that that cycle could spiral, leading to an ice-free summer Arctic in as few as five years, according to one prediction. Already, 2007 saw the first year in history that the fabled Northwest Passage emerged, and a scramble to claim territory and exploit oil and gas deposits is under way across the northern latitudes.
"As we predicted last year, 2007 was warmer than 2006, continuing the strong warming trend of the past 30 years that has been confidently attributed to the effect of increasing human-made greenhouse gases," said James Hansen, director of NASA GISS.
"It is unlikely that 2008 will be a year with truly exceptional global mean temperature," said Hansen. "Barring a large volcanic eruption, a record global temperature clearly exceeding that of 2005 can be expected within the next few years, at the time of the next El Niño, because of the background warming trend attributable to continuing increases of greenhouse gases."
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