In 1985, in the middle of an otherwise excellent set of essays, the author-physician Gerald Weissmann laid a memorable egg titled AIDS and Heat. Weissmann’s economic argument against researching an AIDS vaccine hinged on the point that we could save more lives on a per-capita basis by handing out air conditioners in regions prone to heat waves. The argument made sense, of course, only if death toll from both AIDS and heatstroke remained exactly the same.
Needless to say history proved him wrong.
For reasons that should become obvious Weissmann’s misguided essay kept coming to mind as I read this this latest from “skeptical environmentalist” Bjorn Lomborg. Many of Lomborg’s points come close enough to the Weissmann fallacy to qualify as copyright infringement. For example:
The typical cost of cutting a ton of CO2is currently about $20. Yet, according to a wealth of scientific literature, the damage from a ton of carbon in the atmosphere is about $2. Spending $20 to do $2 worth of good is not smart policy. It may make you feel good, but it’s not going to stop global warming.
As with AIDS in 1983 the costs associated with climate change are almost exclusively future costs. Losing one major coastal city (or another one if you count New Orleans) would completely overturn Lomborg’s glib accounting. Updated IPCC estimates suggest that rising sea levels will inundate dozens of them.
It seems logical to expect more heat waves and therefore more deaths. But though this fact gets much less billing, rising temperatures will also reduce the number of cold spells. This is important because research shows that the cold is a much bigger killer than the heat. According to the first complete peer-reviewed survey of climate change’s health effects, global warming will actually save lives. It’s estimated that by 2050, global warming will cause almost 400,000 more heat-related deaths each year. But at the same time, 1.8 million fewer people will die from cold.
Future mortality estimates ignore heatstroke and “cold” deaths (note that Lomborg doesn’t cite where he got his “1.8 million” number) because in the greater scheme of things, those numbers are rounding errors. Two thirds of the human race lives within 37 miles of a coast and roughly one hundred percent of us depend on stable food production. If global temperatures rise to the point that heatstroke becomes a major issue, then rising sea levels will have already forced billions to migrate and shifting agricultural productivity zones will have thrown food production into flux. The scenario in which heatstroke becomes our primary overriding mortality problem simply doesn’t exist.
Like Weissmann on AIDS, Bjorn Lomborg’s polemic on heat shows the fundamental weakness of argument by spreadsheet. Pretty numbers make it too easy to overlook the weak assumptions on which they’re based.