by Judith Curry

This brief summary of the history of scientific understanding of the impacts of climate change is a peculiar history, as histories of science go. – Spencer Weart

Historian Spencer Weart has published a very interesting article in Physics Today: Climate change impacts: The growth of understanding. The whole article is well worth reading; here I excerpt text from the section A peculiar kind of science. Excerpts:

This brief summary of the history of scientific understanding of the impacts of climate change is a peculiar history, as histories of science go. Since the real work began in the 1960s, I have not had occasion to mention a single name of an individual: My actors were committees. I have not even cited any single landmark discovery paper; the committees were looking over dozens of papers, then hundreds, each contributing a little bit to the overall picture. Nor have I described any grand false leads, dead ends, or controversies, which are so common in the history of science. The seat-of-the-pants guesses that scientists started with in the 1960s turned out to be roughly correct; the story was one of adding to the list of impacts, putting numbers to each item, and becoming ever more certain that the things foreseen would indeed come to pass. And in this short article I have certainly not been able—any more than the IPCC in its lengthy reports—to present a convincing case, based on logic and observations, of why anyone should believe the consensus statements.

A closer look, if I had much more space, would certainly turn up plenty of individuals, along with lots of mistakes and controversies about details. Each new idea was first brought up by someone and then argued out at length. Our history of committees is like the swan that glides serenely on the surface while paddling furiously underneath. Still, I haven’t been telling a Whig history, reconstructing after the fact an understanding that never existed at the time. In this peculiar case a consensus was constructed by committees on the fly, a consensus that became increasingly detailed and certain decade by decade. The topic was so important that people recognized very early on that it could not be left to a few individuals making statements to the newspapers. Experts had to analyze the entirety of the peer-reviewed literature, even have elaborate computer studies done expressly for their use, and get together to hammer out conclusions that everyone could agree were scientifically sound. To be sure, in some areas they could only agree on the extent of their uncertainty, but that, too, was a genuine and important scientific conclusion.

On the other hand, many people have argued vociferously against the entire scientific consensus on impacts, right up to the present. For example, a Hoover Institution publication held that “global warming, if it were to occur, would probably benefit most Americans.” There would be lower heating bills and other energy savings. Others emphasized, as a Heartland Institute publication declared, that “more carbon dioxide in the air would lead to more luxuriant crop growth and greater crop yields” while taking no account of the likely heat waves and droughts. No careful study or hard analysis backed up such statements. Our mainstream history, the history of expert committees, stands aside from all that.

The public knew little of how the committees came to exist and nothing of how they functioned. The experts’ consensus reached ordinary people as a few paragraphs, at most, in a news story, boiling down an already much compressed executive summary.

I submit that a major problem in communicating climate realities to the public is that the media, and everyone else addressing the public, feature individual scientists and their discoveries and disagreements. We have scarcely come to grips with committee consensus, a different kind of history of science. You will find no account digging into details of committee deliberations. I haven’t been able to do it here, and I am not sanguine about prospects for getting it done. In fact, the IPCC and the NAS and their members have been highly reluctant to make public any documents or recollections about just what goes on in the committee deliberations. Only recently, under pressure from critics, has the IPCC made its review process entirely transparent to the public. Be that as it may, I suggest historians and social scientists should give more attention to those committees. If we did, the public would have a better idea of how “science” comes to say what it does say about global warming —and a good many other issues.

JC reflections

Weart’s characterization of climate science by committee consensus seeking seems to fall under the rubric of post normal science. In this framework, much of the tension in climate science seems to come from scientists who want to behave as physicists (i.e. ‘real scientists’) versus committee based consensus seeking and consensus supporting.

So why have climate scientists, coming from a heritage mostly of physics and chemistry, acquiesced to science by committee? I submit that the older generation (my generation and older) have come up through the traditional sciences and are relatively vocal in their opposition (the phenomenon of the emeritus faculty members who seem to object to the consensus). Whereas younger climate scientists have come up through the system more accepting of the consensus by committee approach.

Well this is certainly a rich subject for science historians!