Study: U.S. climate still changing

BOULDER, Colo., Nov. 12 (UPI) -- Scientists say global warming has produced daily record high temperatures twice as often as record lows across the United States in the last decade.

Investigators at the National Center for Atmospheric Research said the Earth's warming is likely to continue the dramatically increasing ratio of record highs to record lows if greenhouse gas emissions keep climbing.

If temperatures were not warming, the annual number of record daily highs and lows being set would be about even, NCAR scientist Gerald Meehl, the lead author of the study, said. Instead, between Jan. 1, 2000, and Sept. 30, 2009, the continental United States set 291,237 record highs and 142,420 record lows.

The scientists said they also determined much of the nation's warming is occurring at night, when temperatures are dipping less often to record lows. That, they said, is consistent with climate research showing higher overnight lows should be expected with climate change.

"One of the messages of this study is that you still get cold days," Meehl said. "Winter still comes. Even in a much warmer climate, we're setting record low minimum temperatures on a few days each year. But the odds are shifting so there's a much better chance of daily record highs instead of lows."

The study that included researchers from Climate Central, The Weather Channel, and the National Oceanic and Atmospheric Administration has been accepted for publication in the journal Geophysical Research Letters.