Greenhouse gases warming North America unevenly
WASHINGTON (AP) -- Climate change caused by greenhouse gases is warming the United States, though unevenly, government researchers said Thursday.
"The continent as a whole is warming, mostly as a result of the energy sources we are using," William J. Brennan, acting administrator of the National Oceanic and Atmospheric Administration, said at a briefing about the U.S. climate since 1951.
There is, however, a "warming hole" where no change occurred in the center of the country, roughly between the Rocky Mountains and the Appalachians, added Martin Hoerling of NOAA's Earth System Research Laboratory.
Last year the International Panel on Climate Change, studying the planet as a whole, concluded that global warming is "unequivocal, is already happening, and is caused by human activity."
Thursday's report localized the analysis, concluding that average surface temperatures over the United States have increased 1.6 degrees Fahrenheit (0.9 C) since 1951, nearly all in the last 30 years.
Weather observations are the Rosetta stone, Hoerling said: "We see a cause-effect relationship in data."
He said that human-induced warming is the overall driving factor and also is the major cause of changes in sea-surface temperature.
Sea temperatures, in turn, result in the uneven changes over land by affecting wind and storm movement. Climate experts have learned a lot about this effect in recent years by studying the periodic El Nino and La Nina patterns of unusual warming or cooling of the tropical Pacific Ocean and how those changes alter weather.
Currently the Pacific is in a neutral condition between the two extremes, and in a separate report Thursday NOAA's Climate Prediction Center said neutral conditions are likely to continue through early next year.
And in yet a third report released Thursday, NOAA's National Climatic Data Center reported that November's average temperature for the contiguous United States was 44.5 degrees (6.9 C), 2.0 degrees (1.1 C) warmer than average. It was the warmest November on record for the Western United States.
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