Partial Response to the London Channel 4 Film "The Global Warming Swindle"
I believe that climate change is real, a major threat, and almost surely has a major human-induced component. But I have tried to stay out of the `climate wars' because all nuance tends to be lost, and the distinction between what we know firmly, as scientists, and what we suspect is happening, is so difficult to maintain in the presence of rhetorical excess. In the long run, our credibility as scientists rests on being very careful of, and protective of, our authority and expertise.
The science of climate change remains incomplete. Some elements are so firmly based on well-understood principles, or for which the observational record is so clear, that most scientists would agree that they are almost surely true (adding CO2 to the atmosphere is dangerous; sea level will continue to rise,...). Other elements remain more uncertain, but we as scientists in our roles as informed citizens believe society should be deeply concerned about their possibility: failure of US midwestern precipitation in 100 years in a mega-drought; melting of a large part of the Greenland ice sheet, among many other examples.