Global Warming: Consensus Grows

With the Internet distribution this past August of a draft synthesis report by the three Working Groups of the Intergovernmental Panel on Climate Change (IPCC), suddenly global warming is back in the news. The report concludes that “the observed increase [in global temperature] over the last century (0.3°C–0.6°C, 0.5°F–1.1°F) is unlikely to be entirely due to natural causes . . .” While that statement may not sound very strong, it is extremely significant. Scientists are by nature a conservative lot, and few have felt comfortable in the past stating that global warming is here.

The IPCC Report is still in draft form and not scheduled for approval by the full panel until December in Rome, but it is already drawing lots of attention—including two front-page stories in