Climate Science and Macroeconomics
Nick Rowe compares and contrasts climate science with macroeconomics. After listing some similarities, he turns to differences.
D1. Macroeconomists are trying to explain people; climate scientists aren’t. People are harder to explain. In particular, people’s behaviour depends on what they expect to happen in future, so we have leads as well as lags in our causal modeling. That makes our job harder.
D2. I think we have more useful data. If we want to look at the effect of money on inflation, we can look at different countries, as well as different historical episodes. If they want to look at the effect of CO2 on temperature, they only have world data. And we have lots of natural experiments in historical memory. That makes our job easier.
Thanks to Mark Thoma for the pointer. Read Rowe’s whole post.
The main reason I am a climate skeptic is (D2). My reasoning is very simple. Macroeconomists do not have enough data to verify hypotheses. (See my lost history paper.) Climate science has even less data. Therefore, climate science is even less reliable.
Before you protest that climate scientists have hundreds of years of data and many observation points, read the “lost history” paper. The point is that the information content of a seemingly large data set can in fact be quite low. Macroeconomists spent a good part of the late 1970’s and the 1980’s coming to terms with this (although some economists did not come to terms with it to the extent that I think is warranted). I think that climate scientists are unwilling to come to terms with it. That is why I am willing to challenge their expertise, even though I have only a superficial knowledge of the theories involved.
My sense is that another common feature of macroeconomics and climate science is that protagonists resort to bullying and ad hominem attacks relatively more often than in microeconomics or in other scientific fields.
[UPDATE] In my days as a macroeconometric model jockey, I often used “add factors” to make the equations fit the data better. But I never used them to distort the data. I disagree with those who think that “climategate” is a typical scientific brouhaha. This is at least one standard deviation away from normal academic behavior.]