"Scientists sifting for trends in record high and low temperatures across the United States have found  more evidence of long-term warming of the climate, with the biggest shift coming through a reduction in record low nighttime temperatures. That is a pattern long predicted by climate scientists using computer simulations. The researchers said they sifted data carefully to avoid possible distortion of trends related to changes in instruments or conditions at and around weather stations."

Andrew C. Revkin reports for Dot Earth in the New York Times November 12, 2009. [2]