Climate Change: Part 1: Models, Uncertainty, and Silly Politics
After the silliness of the past few weeks, I feel compelled to weigh in on the science and politics of climate change. Lately we’ve seen serious breaches of professional ethics, embarrassing retractions from the IPCC, and an epic snowstorm that delighted skeptics., among other things.
The intellectual level of our public debate is depressing enough, but the unecessary invective and collective illogic that permeates this issue in the United States is truly embarrassing. The critiques below apply equally to the ignorant GreenPeace canvasser harrassing you for money to ‘save the planet,’ to the Hannity-esque blowhards who rejoice every time it gets cold, and to the professional scientific community that has radically failed to teach the public just what climate science does, and more importantly what it doesn’t.
Observation 1: Our predictive faculties are epistemologically distinct from our explanatory faculties.
The former is prone to massive error while the latter can be more solidly specified. We can confidently and deductively affirm a physical process – the insulating properties of CO2, methane, etc… – and logically infer that, all things being equal, an unabated growth in their atmospheric concentrations will have an aggregate warming effect. Yet this is epistemologically unrelated to predictions about specific weather patterns, and the gap between the two kinds of knowledge is enormous. The predictions that garner so much press are the weakest parts of the science. They are inductive, anecdotal claims using idealized (i.e., necessarily false) models of global climate. So here’s the catch: the science is solid, AND the predictions will always be wrong; and the frustrating irony is that the closer one looks (i.e. the more detailed your model becomes) the worse the predictions get. Yet none of this failure does anything to deny that the aggregate phenomenon is indeed taking place at the specified level of analysis: global climate.
Observation 2: Causality can only be inferred probabilistically. No single occurrence (heat wave OR cold snap!) validates any general inductive theory.
Thus at any given time we can only generalize about the impact an aggregate phenomenon – increased concentrations of CO2 – will have on any particular place and time. So liberals, please!, enough already with the “Hurricane Katrina, the California drought, etc… were caused by global warming” shtick. You’re wrong. Conservatives, please!, enough already with building snowmen at the White House to claim that climate change isn’t real. You’re wrong. Such statements are not, and cannot be, causally true. All you have, on both sides, is the false correlation of isolated events to fit a large causal pattern. Reasonably sure of the long-term trajectory, the localized effects (positive and negative) will be dramas we cannot predict and will simply have to watch unfold. David Hume, where are you when we need you?