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Economist Arnold Kling is skeptical about whether global warming is caused by carbon emissions or not, and in this TCS Daily piece he explains why.

I am not a skeptic about the rise in average temperatures. Nor am I skeptical that the amount of carbon dioxide in the atmosphere has been increasing. However, I remain skeptical about the connection between the two.

My question is this:

what are the most persuasive reasons for believing that the rise in temperature is due to increased atmospheric carbon dioxide?

What I am looking for is evidence that I can use to overcome my skepticism. My view of climate change is that we have about three data points–an increase in temperatures from 1900-1940, and slight decrease from 1940-1970, and a recent increase. There are a lot of variables that could affect climate, and I wonder how we can be confident about our understanding of the process, given that we have only those three data points to work with.

I have a similar doubt, as readers of this blog might well know. It seems to me that the causal explanations we have are fairly uncertain, and given that this is so, we should be more careful about doing something drastic.

I also find it worrying that two debates have turned into one, making both of them rather confusing and misguided. First there is the scientific debate about what is going on. My layman feeling is that nobody can say with great confidence that they know, and that more data collection and better explanatory models are needed. Second, there is the political debate about what should be done about the whole thing. This has turned into a quasi-religious cult of doomsday sayers, throwing all sense out the window, and refusing to compare the assumed benefits of their proposals with the costs.

There are several unfortunate things here. One is the mix-up of these two separate debates, which has lead to a situation where a person’s political views makes them hold a scientific view based on politics. This is clearly not good if one wants to know whether carbon emission are heating up the planet or not. Also unfortunate is the alarmism. Even if it is true that carbon emissions cause global warming, and that the effect of this is what Al Gore and his chums say it is, it does not follow that we should do everything possible about it. We still need to compare different measures and see which ones are efficient, and figure out how much they cost. Assuming that technological development does not stop, it also seems rather likely that we can come up with better methods of cooling the planet than those currently available.

Taking into account that our current knowledge appears to be rather uncertain, and that the policy proposals on the table are rather costly, I would prefer if we did not do too much at the moment. A moderate carbon tax might be reasonable, but huge reductions of emissions would probably do more harm than good. When we know more we may find reasons to take stronger action. We may also find that the causes are quite different, and require something else to be done. And we may invent new technological devices that make it cheaper to reduce emissions, making it more worthwhile to do it.

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