I've mentioned Richard Alley before, with good reason. You can get a flavor of the reason by looking at his Bjerkenes lecture The Biggest Control Knob: Carbon Dioxide in Earth's Climate History.
It's about 50 minutes, and you can skip the introduction to save a little time. One thing not to miss from the introduction, so I'll mention it here, is the title of Richard's popular book The Two Mile Time Machine. In it, he discusses how we (he) figures out what climate was like from examining ice cores. First hand discussion.
Digressing to the personal a second, I do know him personally. I was a guest lecturer in the 1991 edition of the class he mentions. My thing at the time being deep ocean circulation, with some concern about how that affected atmospheric CO2 levels.
Back to his talk; he says a few things that I think are particularly useful for thinking about how science is actually done. At one point, he notes that good scientists doing good work come to one conclusion -- one which makes for a conflict between two sorts of data. And there are other good scientists also doing good work, but differently, who come to an answer that shows no conflict between the two types. Now, who's right? We need to do more work. It isn't that one group is bad people, or doing bad science. There's a conflict in the results, so we need to learn more, which means do more work to understand how the conflict comes about. Probably (my opinion) it means that there's a loophole in one of the sorts of analyzing the geologic record, so that it doesn't only record what the method expects. Finding that loophole is the challenge.
You'll see, also, something about what scientists are like inside. Most of us aren't as demonstrative about liking our subjects. But nobody can watch Richard for more than a few minutes and not realize that he loves his subject. The rest of us do, too, just not so obviously.
This all actually relates well to the post I promised in my last note. It turns on looking at ice cores and CO2, and Richard will fill you in on parts of the story that surround the two.