Although I wouldn't consider "State of Fear" the end-all source for all things global-warming, it was a terrific book. This article does bear an uncanny resemblance to the tripe published by the environmentalists in the book, however.
As you probably know, Crichton's footnotes in the book were real even though the story was fiction. So, to that extent, I consider it a pretty good source - especially since we can check the footnotes ourselves.