Record U.S. Warmth of 2006 Was Part Natural, Part Greenhouse

摘要

Climate scientists usually hesitate to point to a single climate extreme and say, "That's the greenhouse at work." Climate naturally swings to and fro so much that it can be tough to pick out the influence of the strengthening greenhouse on a hurricane season, say, or on one country's climate over the course of a year. But four National Oceanic and Atmospheric Administration (NOAA) climate scientists report in a paper in press at Geophysical Research Letters that the greenhouse was behind more than half of last year's record-breaking warmth across the contiguous United States. By their reckoning, global warming in 2006 was aggravating all manner of U.S. extremes: severe droughts, the rising cost of air conditioning, the cold-sensitive pine bark beetle ravaging once-cool western forests, and maybe even some midwinter daffodils.