Scientific accuracy
As a rule, I have found that the basic scientific reports that are eventually used as the foundation for some crackpot environmental policy are extremely careful not to jump to conclusions, and are quite clear about the uncertainties involved.
When the radical environmentalists get a hold of these same reports, somehow all this uncertainty gets lost along the line. Sometimes this process occurs as early as the drafting of the report's abstract.
And the press, of course, mindlessly repeats whatever the radicals say, so we end up with the impression that a study has come to conclusions that it never did.