Several times in the Cook lecture I couldn’t resist smiling and thinking that he couldn’t believe that himself. Could he? The first time was when Cook said that for complicated issues we rely on the experts and then gave an analogy: bridges. The public is trusting those who build bridges. They trust that bridges are save to cross. The implication seems clear. Why shouldn’t we give the same trust to our climate scientists? Those are the “experts” when it comes to the climate.
I heard that one in several variations and it is rather funny if you think about it.
Sure, I trust that crossing a bridge is save. I realize that bad things can happen (like for example the Tacoma bridge), but this happens rather seldom. It is fair to say that bridge engineers know what they are doing and I have no problem trusting their expertise when walking across a bridge.
Analogies are great, but only go as far as the similarities go. Climate science is a different kind of breed compared to engineering. People build bridges for many thousand years. In engineering the basis is well established, the properties of the materials well known. Feed this into a model and it will work pretty reliable.
Compare that to climate science which is a fairly new science that is studying a very complex matter. Many things are not (well) known, observational data is only available from the end of the 1970s, uncertainties are huge, the science politicized,…
So the comparison is rather flawed. Let’s make the correct comparison.
Suppose you knew that the technology of building bridges was fairly new. Suppose you knew that the technology of bridge building was based on scarce and incomplete observational data. Suppose you knew that only few bridges were build and that most of them collapsed. Suppose you knew that the properties of the materials were hardly known, there were huge uncertainties on how all these things fit together and nobody knew exactly how they would act under a load.
Would you be able to cross that bridge in a relaxed way?
When lookingt at other commentaries they seem to focus more on the question “if 97% say the bridge will collapse and 3% who say the bridge will not collapse, who to believe?”. Maybe I missed something while making notes. For some reason I connected the “expert” statement with the analogy, probably because they followed each other. Have to check with the video how it was actually brought.
Whatever be the case, the analogy will always fail because of the incorrect comparison of bridge engineers (who study a well defined, well understood topic) with climate scientists (who study a complex system with huge uncertainties). Therefor it can easily be reversed. If that 97% agreement is based on incomplete data, processes not yet (well) understood,… then whatever the level of agreement is that the bridge will fail, it will be basically meaningless.
There are also many other possible analogies. See below in the comments for additional thought experiments.