The Maddening Vaccination/Global Warming Comparison

In the most thoroughly unsurprising news of the week, the New York Times tried to make the facile, misleading comparison between the GOP's stance on global warming and the recent, ill-advised comments about vaccination.

The vaccination controversy is a twist on an old problem for the Republican Party: how to approach matters that have largely been settled among scientists but are not widely accepted by conservatives. 

It is a dance Republican candidates often do when they hedge their answers about whether evolution should be taught in schools. It is what makes the fight over global warming such a liability for their party, and what led last year to a widely criticized response to the Ebola scare.

That the Times would make this comparison was both inevitable and deeply frustrating.

Let's move beyond issues about whether people "believe" in global warming to the more relevant issue: what people actually want to do about global warming. For policy purposes, it is basically equivalent to believe that global warming is a hoax and that global warming is happening, but that doing anything to stop it is not worth it.

Let's also avoid discussing the complex ideological and political mix of the anti-vaccine population. (The Times is insinuating that opponents to vaccination come from a largely conservative population, but polling data is much more ambiguous.)

Conservatives (rightfully) almost universally cite Jim Manzi when talking about climate change. I'm going to quote a piece he wrote a few years ago for The New Republic that I think holds up fairly well:

The only real argument for rapid, aggressive emissions abatement, then, boils down to the weaker form of the uncertainty argument: that you can’t prove a negative. The problem with using this rationale to justify large economic costs can be illustrated by trying to find a non-arbitrary stopping condition for emissions limitations. Any level of emissions imposes some risk. Unless you advocate confiscating all cars and shutting down every coal-fired power plant on earth literally tomorrow morning, you are accepting some danger of catastrophic warming. You must make some decision about what level of risk is acceptable versus the costs of avoiding this risk. Once we leave the world of odds and handicapping and enter the world of the Precautionary Principle—the Pascal’s Wager-like argument that the downside risks of climate change are so severe that we should bear almost any cost to avoid this risk, no matter how small—there is really no principled stopping point derivable from our understanding of this threat.

[snip]

So what should we do about the real danger of global warming? In my view, we should be funding investments in technology that would provide us with response options in the event that we are currently radically underestimating the impacts of global warming.  In the event that we discover at some point decades in the future that warming is far worse than currently anticipated, which would you rather have at that point: the marginal reduction in emissions that would have resulted up to that point from any realistic global mitigation program, or having available the product of a decades-long technology project to develop tools to ameliorate the problem as we then understand it?

The best course of action with regard to this specific problem is rationally debatable, but at the level of strategy, we can be confident that humanity will face many difficulties in the upcoming century, as it has in every century. We just don’t know which ones they will be. This implies that the correct grand strategy for meeting them is to maximize total technical capabilities in the context of a market-oriented economy that can integrate highly unstructured information, and, most important, to maintain a democratic political culture that can face facts and respond to threats as they develop.

Manzi is basically taking a cost/benefit approach to global warming, and finds that the emissions reductions that are needed to prevent it are simply not worth the cost. If the "worst case" scenarios hit, he believes that we will be better off if we had spent resources on developing technologies that could mitigate their effects, rather than by targeting emissions targets that will dramatically reduce people's standards of living.

I find Manzi highly persuasive. You may not, but the bottom line is that this is a principled, reasonable argument against emissions targets that accepts that the climate is changing, and that human activity is part of the cause. The core reason why Manzi's arguments are at least justifiable is because of the uncertainty in modeling. To use another Manzi frame, climate modeling is a domain of extremely high causal density: it is very difficult in areas of high causal density to disaggregate cause and effect. We think that carbon emissions result in incremental increases in global temperature. But we also think that solar activity changes temperature. And we think that volcanic activity changes temperature. And we think that the oceans absorb a lot of carbon. There's a lot of complexity in all of this; it is very hard to get to the bottom of it. Climate modeling is not like math, physics, or chemistry. Or, for that matter, vaccination.

Like the environment and climate, the human body is a complex system that we're still learning a lot about. But we have managed to reduce some of our uncertainty about the body--and learn about medicine and health--because we can at times control confounding variables and do experiments. Vaccination is one of many health benefits that have come out of this experimental process. We have been field testing vaccines for over 200 years, going back to Jenner and cowpox. The idea of variolation--which is basically the same principle--goes back even longer, having been practiced with some regularity in China and Turkey, among other places.

The widespread use of vaccines targeting very specific diseases coincided with dramatic drops in the incidence of those diseases over the 20th century. Pessimistic climate models may be entirely right about the negative effects of carbon emissions, but the bands of uncertainty are much, much greater.

Moreover, the collective action problem is far less significant with vaccines than it is with the environment, because there is an immediate benefit to the individual who gets vaccinated. True, as Megan McArdle points out, there is a collective action problem at high levels of immunization, as people free ride on herd immunity rather than facing whatever health risks come with vaccines. But in a world where herd immunity was not an option--say one where vaccines were scarce and limited by randomized drawings--there would still be strong, selfish incentives to vaccinate. Emissions cuts to fight global warming are precisely the opposite, in that the only benefit kicks in after we reach a critical mass of people or countries cutting emissions.

Lastly, the cost of vaccines are quite minor: low health risks, small financial expenditure (often paid for by the government or a third party, these days), a brief sting of pain in the arm, and perhaps some soreness for a few days. Consequential emissions cuts would require dramatic costs and lifestyle changes for billions of people, with an unknown benefit.

So, we have three critical differences:

• Vaccines have a proven level of effectiveness, while the effectiveness of various emissions targets remain in question.
• Vaccines produce significant individual benefits, in addition to the social herd immunity benefit. Emissions targets largely require individual sacrifice before reaching a potential collective benefit.
• Vaccines are low cost; emissions targets would be more costly and disruptive.

These differences are so material that they make any direct analogy--or narrative surrounding the two together--fall somewhere between uncharitable and deliberately obtuse. The Times should be better than that.