Why I Accept the Reality of Anthropogenic Climate Change

As late as the end of 2008 I was avowedly agnostic about whether global warming was even real, much less whether it was anthropogenic. I am no longer skeptical. I have convinced myself of its reality through a very simple epistemological argument which I think should be a decisive one for anyone whose level of knowledge of climate science is similar to my own. The same argument has convinced me that people with my level of knowledge who do not accept anthropogenic climate change either have been insufficiently reflective or have allowed ideology or emotion to cloud their judgment.1 I would like to present my argument here.

I am not a climate scientist. I do not have anywhere near the expertise necessary to understand the peer-reviewed work upon which consensus documents like the IPCC Assessment Reports are based. If you have that level of expertise then my argument does not apply to you. But if you are a layman like me—and the overwhelming number of people involved in this debate are—then my argument applies.

First, let us take note of the fact that among those who do have expertise in climate science, the consensus is that anthropogenic climate change is both real and significant. Now, as far as I can tell, four possibilities present themselves:

(i) The scientific consensus has it right. There is nothing inherently improbable about this.

(ii) The overwhelming number of climate scientists are so stupid that they have completely missed devastating arguments so simple that even a layman can understand them. Most of the skeptical arguments pitched to laymen invite their targets to take this standpoint. I will presume that intelligent readers will, after a moment’s reflection, dismiss both this standpoint and all of the simplistic arguments that require it. Even a few minutes of fact-checking underwrites this dismissal, though for some reason the lay skeptics I have met never seem to have fact-checked their arguments—I have to be the one to tell them that no, there was no worldwide scientific consensus on global cooling in the 1970s, and such.

(iii) The overwhelming number of climate scientists are liars, publishing nothing but flimsy or fraudulent work, and giving the nod to the entirely flimsy or fraudulent work of others, in a vast, somehow globally coordinated effort either to (a) advance their own careers, or (b) push forward an even more massive ecofascist—or, most recently, Chinese—agenda of which they are only one component. Sometimes all of these scientists are even presented as part of a UN-driven religious conspiracy to control the world populace under false pretenses. One can practically hear the whirr of black helicopters, dispersing their deadly payload of climate scientists across the world, each one tattooed doubly with the sign of the Illuminati and the mark of the Beast. Again, I will presume that brief, serious reflection will put all such contentions beyond the pale for intelligent readers.

(iv) The scientific consensus has it wrong, for reasons sufficiently subtle or technical as to currently elude their understanding, and all the more the understanding of a non-expert. This possibility, like the first, seems genuine: the scientific community is not infallible, and sometimes one expert sees the answer that the consensus has missed.2

The only two choices not immediately beyond the pale are choices (i) and (iv): either one must accept the scientific consensus, or one must believe that the scientific consensus has missed something sufficiently subtle and technical to elude their notice or understanding. For laymen, I cannot see that we have any choice but to go provisionally with the former. It is a simple numbers game: the consensus of experts does, in fact, get it right more often than the few dissenters. Not always, but certainly often enough for it to be the only appropriate bet for a layman. To be sure, you may come across a skeptical expert who makes arguments that seem plausible to you, but you must ask yourself: do you truly have the expertise necessary to justify the judgment that this skeptical expert’s arguments outweigh the contrary arguments of the overwhelming number of his peers?

Again, I am not making any argument about what an expert should believe: if you have studied climate science enough to have a doctoral-level understanding of the field, and you still reject anthropogenic climate change, more power to you—but you should be arguing with other experts, not trying to incite a mob of laymen who are in no position to rationally adjudicate your dispute.  My primary message is to the mob: you and I are in no position whatsoever to adjudicate the dispute. We should stop pretending that we are.

Let me offer a couple of concluding notes, to forestall misunderstanding:

First, this essay is a defense of science, not a defense of lay environmentalism. To be sure, sizable contingents of lay skeptics—including most of the ones who accept stances of type (ii) or (iii)—clearly have adopted their stances for purely emotional, ideological, or religious reasons. However, the same is true of sizable contingents of lay environmentalists, vast numbers of whom neither understand nor care about science. The only difference is that, mostly by happenstance, the scientific consensus has confirmed claims that are more on the environmentalist side. I do not, therefore, find nearly as many environmentalists blithely accusing the overwhelming majority of scientists of rank stupidity, cowardice, or dishonesty. Had the scientific consensus reached a different conclusion than it has, I surely would have had to aim this essay against lay environmentalist attacks on science; the conclusions of the scientific consensus being what they actually are, I must deal with the attacks that actually exist.

Second, I am not much involved in the question of what humanity ought to do about anthropogenic climate change; I think the question almost certainly is rendered academic by the intrinsic selfishness and short-sightedness of all of the countries that matter. Calls for sacrifice are naive: absent a clear demonstration of how clean energy will put more cash into everyone’s pockets, there is no point in trying to encourage a meaningful action. It is interesting to think about whether such a demonstration could be provided, but I think most of my time is more usefully spent studying quantum mechanics and 18th-century  Scottish philosophy.

To end on a positive note, though, I am in any case sufficiently turned off by the obnoxious noises coming from the ideological factions on both sides—which do so well to polarize one another and everyone in between—that I find myself actively hoping for the end of the world, and the attendant silence of its aftermath.


1 I charge my former self with insufficient reflection. Somehow, I managed to convince myself that I had done due diligence to the debate by reading Michael Crichton’s State of Fear, becoming aware of skeptics here and there with arguments that went over my head as much as the consensus arguments, and exchanging with some of my equally naive philosopher friends our impressionistic sentiments about how solar variability might be responsible for the whole damn thing, as though mainstream scientists had never thought of that.

2 One of my skeptical philosopher colleagues, who I will leave anonymous, argues that there is fifth alternative: at some point, the thesis of anthropogenic climate change “dovetailed with political and environmentalist interests, and consequently got wind in its sails as a result of dedicated funding and momentum. The scientific establishment began to seek confirmation of the hypothesis. There was no conspiracy, no incompetence, no stupidity, no malevolence, just momentum.” In short, the consensus scientists produce poor, biased research (so blatantly poor and biased that even nonspecialists like my friend can see all of the fatal problems), simply because they want to gorge themselves on the government feedbag. How this charge is supposed to differ from a charge of conspiracy, incompetence, stupidity, or malevolence, is entirely beyond my ability to fathom. Imagine my saying to you: “I don’t think you are incompetent or dishonest. I just think that all of the research you have done and all of the conclusions you have drawn are completely invalid, and that they are purely the result of your seeking confirmation for a hypothesis in order to get dedicated funding. But no, again, I don’t think you’re incompetent or dishonest.” This clearly is an instance of option (iii)—all the polite wording in the world doesn’t dampen the substance of the charge one iota.


How to talk to a climate sceptic

RealClimate.org: Response to common contrarian arguments

Intergovernmental Panel on Climate Change