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Re: The Climate Change Debate


Jerry — Thanks for the clear and respectful reply. Let me respond to your two points.


In regard to your first point: Yes, you understand me exactly when you say:

Even if we accept the absolute worse case scenarios of future warming offered by the IPCC and the Stern Review on the economics of climate change, we still find that a hotter, richer world (that is, the likely path for a business as usual scenario) is better for human well-being than are the alternative scenarios where we actually act to reduce greenhouse gas emissions

I have written words to this effect in many publications, including National Review, The Weekly Standard, and presumably most apropos for this discussion, your own organization’s online journal. Here’s what I said last August in Cato Unbound:

In summary, then, the best available models indicate that 1) global warming is a problem that is expected to have only a limited impact on the world economy and 2) it is economically rational only to reduce slightly this marginal impact through global carbon taxes. Further, practical knowledge of the world indicates that 1) such a global carbon-tax regime would be very unlikely ever to be implemented, and 2) even if it were implemented, the theoretical benefits it might create would almost certainly be more than offset by the economic drag such a regime would produce. Other than that, it sounds like a great idea.

However, in that same article, I go on to say that the key concern is that the actual impacts of global warming might be worse than expected:

A … serious objection is that our forecasts for warming impacts might be wrong, and global warming could turn out to be substantially worse than these models predict. Climate models are, at a minimum, non-validated. Predicting the cost impact of various potential warming scenarios requires us to concatenate these climate predictions with economic models that predict the cost impact of these predicted temperature changes on the economy in the 21st, 22nd, and 23rd centuries. It is hubris to imagine that these can guarantee accuracy, and impossible to validate such a claim in any event.

Now, climate and economics modelers aren’t idiots, so it’s not like this hasn’t occurred to them. Competent modelers don’t assume only the most likely case, but build probability distributions for levels of warming and associated economic impacts (e.g., there is a 5 percent chance of 4.5 °C warming, a 10 percent chance of 4.0 °C warming, and so on). The economic calculations that comprise, for example, the analysis by William Nordhaus that I referenced earlier are executed in just this manner. So, the possibility of “worse than expected” impacts really means, more precisely, “worse than our current estimated probability distribution.” That is, we are concerned here with the inherently unquantifiable possibility that our probability distribution itself is wrong.

So, once we clear away the underbrush, we can see that the case for a carbon tax or a cap-and-trade emissions rationing system is really that it would be a hedge against the risk that actual damages from warming would be much, much worse than current risk-adjusted projections indicate. Would it be a smart investment?

This is why the uncertainty in climate models (which is highlighted in the open letter), cuts for the arguments in favor of cap-and-trade, carbon taxes, and similar mitigation efforts, rather than against them. In the article, I then go into a lot of detail about why I believe that aggressive emissions mitigation is clearly unwarranted as a hedge against this risk (I also do this in the 2007 NR piece). This is why I said in my prior post to which you are responding that the informed global warming debate is centrally about the “deep uncertainties that surround it.”


In regard to your second point: Fair enough, it’s your money, and in the end, editorial judgments are judgments. I went into some detail in the 2007 NR piece about why I think it is not only correct on the merits, but also a better political strategy to accept the valid scientific findings, and then point out that they do not have the implications for massive new tax and regulatory schemes that the Left argues, rather than to debate the scientific findings and not participate in the debate about what to do about them. I believe that events since then — most particularly the arguments that appeared to most successful in defeating the proposed climate change legislation last year, and that appear to have the most traction in, hopefully, forestalling it this year — have validated this viewpoint. I went through this rationale in a blog post last summer.