It's an article of faith among the green fraternity that the correct response to anyone who questions the climate change orthodoxy is the argumentum ad hominem. Or to be more precise to issue a barrage of ad hominems. Or to be even more precise issue a barrage consisting of any old logical fallacy so long as the truth and facts of the issue at hand are avoided. These accusations can be anything from "this bad person has right-wing political opinions" to "this bad person once said something that turned out to be incorrect" to "this evil spawn of Satan once spoke at an oil company-funded seminar".
There is a good example at Greenpeace's blog today, where David Rose is taken to task because, in a sidebar article making the point that in the 1970s we were all told that we were facing an imminent ice age, he used a graphic of a Time magazine cover that subsequently turned out to a spoof. The blog post's author, Graham Thompson, pretends that this is tantamount to drowning puppies, but even a cursory examination of the details suggests that handwaving and shouting and smearing are all he has got: what Rose said about the 1970s is indisputably true.