Bayesian Investor Blog

Book review: Cool It: The Skeptical Environmentalist’s Guide to Global Warming by Bjørn Lomborg.
This book eloquently counters many popular myths about how much harm global warming is likely to cause, but is sufficiently partisan and one-sided that it will do more to polarize the debate than to resolve disagreements. Many of his criticisms of the alarmists are correct. Reading this book in combination with writings of his opponents will give you a much better perspective than reading only one side of this debate.
Selective reporting gives the impression that global warming is causing more deaths, but Lomborg reports that warming will cause reduced deaths for the foreseeable future, mainly through reduced cold-related cardiovascular deaths. He claims warming won’t cause a net increase in deaths until at least 2200, but I expect that uncertainty about medical innovation makes predictions more than a few decades ahead not credible. Even for the next few decades, he exaggerates the evidence. What he calls “The first complete survey for the world” covers the entire world, but only tries to model the effects of the 6 types of disease for which global information is available, and its authors clearly deny knowing whether other diseases have important effects. Lomborg claims there will be 1.4 million fewer deaths in 2050 due to global warming, but he seems to get that number from the effects of only two disease types, whereas the paper he cites predicts 849252 fewer deaths from 6 disease types.
He is often too dismissive of the possibility of technological improvements. For instance, he claims that sticking to Kyoto commitments through the 21st century “would get ever harder”, yet I can imagine a variety of ways it could get easier. He mentions specific dollar costs for complying with Kyoto for a century without hinting at the large uncertainties in those guesses.
In one place he analyzes Kyoto as if it were a foreign aid program, and says that it would do 16 cents of good in developing countries for every dollar spent. I assume he considers this an argument against Kyoto. Since 16 cents might help a person in a developing country more than a dollar helps a person in a developed country, and there is some reason to suspect that few large aid programs are more than 16 percent efficient, it could easily be considered a weak argument for Kyoto.
Sometimes he’s blatantly careless, such as when he talks about “reducing [hurricane] damage by almost 500 percent”.
He appropriately criticizes the Stern report’s use of a suspiciously low discount rate (which has major implications for how much we should do now), but he doesn’t provide a clear explanation of that issue, nor does he say what his preferred model uses (a review on Salon says it uses a 6 percent discount rate, which I suspect only makes sense if we assume a higher economic growth rate than most experts expect).