Back when I was in Chicago I got to hear many conversations about paleoclimate, a field that is phenomenally rich (literally, there are lots of phenomena to explain) and increasingly data rich, but for all the things to explain and all the data to bring to bear, it struck me that conversations that didn’t involve CO2 greenhouse forcing as a crucial mechanism, on time scales from millenia to eons, were few and far between.
Faced with this every day, and faced with an internet burbling about “no such thing” or “trivial effect” every night was an ongoing frustration. At one point I recall asserting that CO2 is crucial in explaining the 100 Ka glacial cycle, but when challenged I had a hard time finding something in the literature that made the claim explicitly.
I’ve discussed this sort of thing recently with both Steve Easterbrook and Paul Baer. It’s implicit knowledge. By the time you are sufficiently enmeshed in paleoclimate to publish a paper, you already know that CO2 is the dominant control on paleoclimatic variation. There is nothing to be gained from publishing a result that is common knowledge. But sometimes a result gets into the lore of a field without making it into the literature at all. In this case, it’s a sort of generalization that every paleoclimatologist makes, that nobody else has any way of finding out, and that is important!
So I was thrilled to see that Richard Alley was going to make this important point in detail in an hour-long plenary talk at AGU this year, entitled “The Biggest Control Knob: Carbon Dioxide in Earth’s Climate History”.
Alley made a truly excellent presentation, in a huge room, standing room only. Since I was standing myself, and carrying some stuff, I couldn’t really take good notes. Fortunately Dave Petley has an excellent summary (once you get past the rock talks at the beginning of his entry, anyway).
I hope the AGU follows through on making the video permanently available. It’s time there was something for people to refer to on this matter. And it’s another interesting case about the distinction between the literature and the knowledge of a field. Interestingly, Alley’s time slot was up against another important event, which Dr Rabett has blogged, and he too has some things to say about the literature as a consequence, in his case about things that do get in that shouldn’t.