Global warming? Blame the Democrats.

An anonymous blog commenter sends the above graph and writes:

I was looking at the global temperature record and noticed an odd correlation the other day. Basically, I calculated the temperature trend for each presidency and multiplied by the number of years to get a “total temperature change”. If there was more than one president for a given year it was counted for both. I didn’t play around with different statistics to measure the amount of change, including/excluding the “split” years, etc. Maybe other ways of looking at it yield different results, this is just the first thing I did.

It turned out all 8 administrations who oversaw a cooling trend were Republican. There has never been a Democrat president who oversaw a cooling global temperature. Also, the top 6 warming presidencies were all Democrats.

I have no idea what it means but thought it may be of interest.

My first thought, beyond simply random patterns showing up with small N, is that thing that Larry Bartels noticed a few years ago, that in recent decades the economy has grown faster under Democratic presidents than Republican presidents. But the time scale does not work to map this to global warming. CO2 emissions, maybe, but I wouldn’t think it would show up in the global temperature so directly as that.

So I’d just describe this data pattern as “one of those things.” My correspondent writes:

I expect to hear it dismissed as a “spurious correlation”, but usually I hear that argument used for correlations that people “don’t like” (it sounds strange/ridiculous) and it is never really explained further. It seems to me if you want to make a valid argument that a correlation is “spurious” you still need to identify the unknown third factor though.

In this case I don’t know that you need to specify an unknown third factor, as maybe you can see this sort of pattern just from random numbers, if you look at enough things. Forking paths and all that. Also there were a lot of Republican presidents in the early years of this time series, back before global warming started to take off. Also, I haven’t checked the numbers in the graph myself.