Lefties sometimes invoke the "precautionary principle" as justifying climate change public policies such as an emissions cap or carbon tax. This has the advantage (for them) of inverting the burden of proof and affirmatively using doubt against skeptics--even if the science isn't settled, they say, we must act immediately to avoid the worst case. This post assumes the soundness and validity of such logic.
I drafted this last weekend on the road without time for external research and links, but it occurred to me that I've seen this debate before--and progressives were on the other side. Specifically, President Bush adopted a new "preemption" policy, which was the first of three rationales he cited for invading Iraq. He reasoned that the widely-shared apprehension of Iraqi WMDs meant we could not wait for a threat to become "imminent."
Of course, it turned out that Iraq had few WMDs (though toppling Saddam advanced Bush's other two objectives). But assessing whether or not Saddam had WMDs demanded predictive judgment, which the Bush Administration made on the basis of the best info available. Whether or not Iraq had WMDs required assessing incomplete and ambiguous intelligence and then deciding: yes or no?
Fair-minded observers should agree that predicting earth's future climate is far more complex. True, analyzing the data is similar to reading intel. But climate numbers are only inputs to computer models of enormous complexity. (The fact that climate models often have been wrong is indirect evidence of the degree of difficulty.) Further, the models output high and low estimates of expected warming, not a binary choice. Such possible ranges (i.e., confidence or expected error) are both huge and hugely significant: some warming might be tolerable or even good, or better mitigated in other ways. So there are multiple possible scenarios supporting numerous public policy determinations.
Finally, my question: if we must act now to reduce alleged global warming based on disputed evidence, doesn't that validate the Iraq invasion? I ask because of the high correlation between warming alarmists and Iraq invasion opponents. Might this syllogism at least slow the carbon cut train wreck while progressives pause and parse: "Uh, um. . ."?