Wasn't there some environmental honcho that wrote explicitly several years ago that they *needed* to exagerate and lie about the environment in order to motivate the population to action? I think he retracted it, but he said it, and I don't think he was opposed by the environmentalists who were his audience.
One was the science editor of Newsweak. I don't recall him retracting it. As far as I know today, lying about the environment is still official Newsweak policy.