It hasn't happened yet. Once they have been thoroughly proven wrong, usually after a ton of regualtions have been passed and class action lawsuits won, they move on to their next looney theory and the cycle starts all over again. There is a sucker born every minute with no end in sight.
That's true, it hasn't happened. It might not happen, either, but it could. Was thinking of the forest fires in the West in those very forests that some environmentalists are trying to preserve as pristine, and how environmentalists might increasingly not be considered as visionary by others, even though they themselves think they are.