Thursday, January 08, 2004
Crichton's speech, called Aliens Cause Global Warming (a kind of cute title which made global warming skeptical types much more likely to cite the speech), is a rebellion against the notion of consensus science. He views such science as the SETI project (Search for Extraterrestrial Intelligence) and predictions of nuclear winter as cases in which policy goals managed to intrude into the realm of science before (or in the absence of) any factual knowledge. This fundamental dishonesty, construing issues about which uncertainty exists as definite, profoundly hurts both science and the relationship between science and the larger culture in which it is immersed. Global warming comes into the picture because he views it as the intellectural progeny of SETI and nuclear winter science: special interest groups/desirable policy aims have succeeded in politicizing the scientific playing field to such a degree that individuals who dispute global warming scenarios are professionally demonized.
Where to begin...
I take large issue with the specifics of Crichton's claims regarding the degree to which we know humans are warming the globe. I don't want to address that here, though, mostly because you can hear that argument elsewhere too (David Appell spent a large chunk of this fall posting on some of these related issues). The point I do want to make lies in Crichton's ignorance of probabilities.
First, though, an admission. Intellectually honest (as in my experience are most) climate scientists tell you that we don't know what the climate is going to do. We certainly don't understand the climate as well as mechanical engineers understand, e.g., how to build a house that doesn't fall down. There's fairly good reasons why this is so which can be boiled down to two main points: 1. The climate is much more complicated than a house. 2. We have only one of them so we can't experiement with the climate and gain some empirical sense of how it behaves (or rather we can - we're doing it right now -- but it's slow and we can really only do it once).
The question, then, is given what we know about the physics and chemistry of the earth's surface is there reason to think that it's possible that we're changing the climate? Is there reason to think that the fashion in which we're changing the climate is serious enough to demand policy changes? Serious in this context can mean two things: firstly whether the changes we can induce are large enough in magnitude to matter and secondly whether they're abrupt enough to matter. Clearly our choice of the correct policy response to changing climate has to hinge on some evaluation of these two questions: a strong policy reponse to global warming might be justified if the harm were very likely, but only moderate magnitude, or if the harm were less likely but the consequences much more serious. This logic is the same sort of logic that underlies insurance premiums. We pay the same sort of premium (roughly) for protection against a really serous hazard that is relatively unlikely (e.g. hurricaine induced property damage in Virginia) as for a less serious hazard which is much more likely (e.g. a car accident).
Look. Crichton's right that scientists should never stop asking questions (there are no facts in science after all, just theory which agrees with observation). But this doesn't mean we shouldn't take out insurance on our changing planet. This doesn't mean we shouldn't ackowledge that humans have it pretty good (climate wise) for the last 10,000 years and that it is in our interest to keep it that way.
MORE LINKS: For years climate change skepticists contended that most climate change was too slow to concern humans (thousands of years). Thankfully that view has now mostly been put to rest through examination of chemical records of climate change over the last 450,000 years (changes of large magnitude 5-30 degrees C happen in decades). Much of that work is summarized in a National Academy of Sciences report available here (pay no attention to the purchase options, you can print out the book chapter by chapted after clicking on the link if you'd like).