The global warming issue has produced quite a few nut0jobs over the years (ELF, Sierra Club, et al.) But I've noticed that the anti-global warming crowd has gotten a few quacks recently too. (Williams, as this topic points out.)
I still find the arguments by fanatics on both sides to to be nothing short of laughable. I've seen people clai mthat global warming is the greatest hreat to humanity (not even close to being true). I've also seen, as one (former I guess) member here claim that solely because it snowed in Las Vegas, that global warming is now proven false (anyone with a kernel of sense knows that the temperature outside is in no way indicative of the existence of global warming, whether high or low. But apparently the entire field of meteorology is now moot as armchair meteorologists believe they understand how climate change works.)
Also, as stated by others, global warming has been used as a tool to generate a ton of political and monetary capital for a lot of people. But as has NOT been mentioned (not even by our "independent" members here) is that the anti-global warming movement is also being used to generate plenty of political and monetary capital.