I was also one of a small number of scientists—mainly ecologists, climatologists and meteorologists—who in the 1970s became concerned about the possibility of a human-induced global warming, based on then-new measurements. It seemed to be an important scientific problem, both as part of the beginning of a new science of global ecology and as a potentially major practical problem that nations would have to deal with. It did not seem to be something that should or would rise above standard science and become something that one had to choose sides in. But that's what has happened...
It is helpful to go back to the work of the Wright brothers, whose invention of a true heavier-than-air flying machine was one kind of precursor to the Mars Landers. They basically invented aeronautical science and engineering, developed methods to test their hypotheses, and carefully worked their way through a combination of theory and experimentation. The plane that flew at Kill Devil Hill, a North Carolina dune, did not come out of true believers or absolute assertions, but out of good science and technological development.
Let us hope that discussions about global warming can be more like the debates between those two brothers than between those who absolutely, completely agree with Paul Krugman and those who absolutely, completely disagree with him. How about a little agnosticism in our scientific assertions—and even, as with Richard Feynman, a little sense of humor so that we can laugh at our errors and move on? We should all remember that Feynman also said, "If you think that science is certain—well that's just an error on your part."
A good starting point in dialogues between strict materialists and theists would be the recognition that scientists work with unproven assumptions and to deny that flies in the face of reality.