IPCC Leaked Already?

Back when I was first on my learning curve about climate science, I remember always being confused about the date for each report of the Intergovernmental Panel on Climate Change. The official publication date would be in one year, but as soon as you did any background research, you would learn that everyone had been chit-chattering about the report in the media well before the year of official publication. Now I understand why. Although the IPCC's fourth assessment report isn't supposed to be out until 2007, the British media are already waving around a draft version of it. IPCC drafts are extremely easy to get your hands on; they're emailed around to countless scientists. But wouldn't it be better to wait until the process is a little bit more complete before leaking? Can't the Brits contain themselves a little bit?