In January, scientists at the National Oceanic & Atmospheric Administration's National Climatic Data Center reported the 2006 average annual temperature for the contiguous U.S. was the warmest on record, surpassing the previous record set in 1998. Based on preliminary data, the 2006 annual average temperature was 55 F—two degrees higher than the 20th-century norm and 0.07 degrees higher than 1998.
U.S. and global annual temperatures now are about one degree warmer than at the start of the 20th century, a change many scientists attribute to greenhouse gas emissions. Warming has increased globally since the mid-1970s at a rate about three times faster than the century-scale trend, and the past nine years have been among the 25 warmest years on record for the contiguous U.S.—an unprecedented streak.
With springtime conditions in much of the U.S. this winter and Democrats gaining control of Congress, discussion of global warming and resulting policy challenges have a new sense of urgency.