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FILE - In this Sept. 30, 2011 file photo, Sailboats and a floating dock lie on the dry, cracked dirt in a harbor at Lake Hefner in Oklahoma City as drought continues to be a problem across the state. The relentless, weather-gone-crazy type of heat that has blistered the United States and other parts of the world in recent years is so rare and off-the-charts that it can't be anything but man-made global warming, a new statistical analysis from a top government scientist says.(AP Photo/Sue Ogrocki, File)

Biggest heat spike in history

An analysis by a top government scientist says the extreme heat and drought seen in the U.S., Europe and other regions in recent years must be global warming. A new study looking at 11,000 years of climate temperatures shows the

world in the middle of a dramatic U-turn, lurching from near-record

cooling to a heat spike.