Bjorn Lomborg reviews for the latest issue of Barron’s a book-length exposition of global warming alarmists’ key arguments.
In a much-quoted paper of 2009, … Harvard University economist Martin Weitzman, co-author of the recently published Climate Shock, brought a direct challenge to his colleagues’ neat models. Weitzman argued that potential catastrophic risks from climate change, even if they are very small, could fundamentally undermine the cost-benefit analysis. If the risk of ever greater catastrophe tapers off too slowly—more technically, if the probability tail is “fat”–then we should mathematically be willing to pay anything to avoid this risk.
Coming from an economist with Weitzman’s prestige, the challenge prompted a response. Critics pointed out that there are other risks with potentially catastrophic outcomes, including asteroids, runaway computer systems, nuclear proliferation, rogue weeds and bugs, nanotechnology, biotechnology, emerging tropical diseases, and alien invaders. If we accepted Weitzman’s argument that we should be willing to pay infinite sums to avert all of these fat-tail risks, how should we apportion the infinities to pay up? As climate-modeler Nordhaus puts it, “We would drown in a sea of anxiety at the prospect of the infinity of infinitely bad outcomes.”
Climate Shock, co-authored with Environmental Defense Fund senior economist Gernot Wagner, relies on the fat-tail argument of the original 2009 paper, but does not confront the weaknesses in that argument. The book has its clear-eyed moments, as when the authors challenge committed environmentalists to understand that it won’t be easy to get off fossil fuels, pointing out that “economists live and breathe trade-offs.” Yet, Climate Shock is mainly a rehash of standard climate-campaign tropes.
Wagner and Weitzman flog the 2012 Hurricane Sandy as a portent of ever-stronger hurricanes hitting the U.S., although the U.S. to date has never seen a longer period without a severe land-falling hurricane. They ignore the fact that the U.N. Climate Panel in 2014 reported that it has “low confidence” in any changes in hurricane intensity over the near term, and that even by the end of this century, it regards the case for stronger hurricanes as only slightly better than flipping a coin, and then only for some regions. …
… Empty scare stories abound. According to the authors, the last time we put 0.04% CO2 in the atmosphere (as we have done now), the world warmed just 1.8 to 4.5 degrees Fahrenheit, but sea levels rose up to 66 feet and “camels lived in Canada.” The camels reference is used seven times, although the actual camels were so-called high arctic camels that still lived in freezing conditions. …
… Early in Climate Shock we read, “Most everything we know tells us climate change is bad. Most everything we don’t know tells us it’s probably much worse.” We can have an informed conversation about the validity of that first sentence. The second sentence flirts with the fat-tail argument, while revealing the authors’ fundamental bias.
What we don’t know cannot favor our preconceptions, simply because we don’t know it. When Wagner and Weitzman tell us they know more than what is known, we know their arguments are weak.
