You can sense the mood on climate change shifting. Ever since Hurricane Katrina, the mainstream media no longer has a doubt. The problem is real, huge, and urgent: Something must be done. Every storm in the hurricane season just starting will strengthen the conviction. Washington will not be immune, but it has a lot of catching up to do. There is no sign of consensus on the issue. There is little sign, even, of intelligent discussion.
It will be interesting to see whether Al Gore's new movie, An Inconvenient Truth, makes a difference. Gore's documentary, a polished live-action version of the presentation that he has been touring round the country for years, is winning glowing notices. Reviewers declare themselves gripped, charmed, and persuaded. If only this man were president, they more or less say. The same thing has doubtless occurred to Gore. The film would have to do very well to become a springboard for a presidential campaign, of course. Still, even if it falls short of that, the movie may change things.
Global-warming activists, Gore pre-eminent among them, are already regarded by most thinking people as having won the argument. The new movie will seal that victory. Science, facts, levelheaded analysis—inconvenient truths, calmly and convincingly presented—are all on their side, or so it is believed. Global-warming inactivists are going to find themselves regarded, even more than before, as purblind bigots. Their criticisms will be seen as not merely mistaken, but intellectually defunct. To oppose Gore's view of the subject will be to align yourself with, say, advocates of intelligent design. More and more, climate-change denial, or anything that can be characterized as such, will be viewed as a kind of shameful, strutting ignorance.
For remaining waverers on the topic, including many who won't see An Inconvenient Truth, the television advertisements produced by the climate-change inactivists at the Competitive Enterprise Institute, a conservative think tank, may be as effective in this regard as Gore's film. Their concept—"some call it pollution, we call it life"—would be difficult to parody. Has a piece of political propaganda ever been less convincing? Gore's movie is propaganda too, of course—but of a superior, extremely effective kind.
So the climate-change activists have overrun the intellectual territory. Is this going to yield better policy? Probably not.
To crush their enemy in the propaganda war, the activists are shrewdly alarmist. Everything points to impending catastrophe, they imply. It is not enough that we have a problem that needs addressing. No, the planet is in mortal danger. Life as we know it is in peril. The tagline for Gore's movie is, "The most terrifying film you will ever see."
This assertion of impending global catastrophe makes it difficult to have a discussion about well-calibrated responses. It makes opposing the Kyoto Protocol on greenhouse gases look like a capitulation to ignorant inactivism—though that agreement was not, in fact, a good way to confront the problem, and ratifying it would not have been in America's interests. It makes the weighing of costs and benefits in different carbon-mitigation strategies look like quibbling over the cost of urgent life-or-death treatment. And it makes talk of adapting to climate change—which ought to be part of any sensible policy—look like reckless disregard of an impending existential danger.
So far as I know, there is little scientific dissent from the view that the planet is warming. There is also a strong consensus that man-made emissions of greenhouse gases are the main reason why. But there is no corresponding consensus on the costs and benefits of warming to date. Evidently, the warming experienced up to now does not qualify as a cataclysm: That danger, the activists say, is still in the future. But once you start looking ahead—a century ahead, as you have to, and as the Intergovernmental Panel on Climate Change does in its projections—wide ranges of uncertainty enter in. A forecast for global temperature in 2100 rests on (among other things) a forecast of greenhouse-gas emissions in the interim, and that estimate depends on decades-out forecasts of worldwide economic growth, energy efficiency, and many other variables, even if you assume "business as usual" (which it won't be). To acknowledge those uncertainties is not to deny that global warming is happening, or that policy needs to recognize the risks. But the idea that strong scientific consensus supports the activists' apocalyptic view of the planet's prospects is wrong.
But never mind the future, you might say. What about now? What about hurricanes? Wasn't Katrina an avoidable catastrophe? Al Gore seems to want you to think so. (The poster for his movie shows a hurricane unwinding from the top of a smokestack.) The current scientific consensus is that warming has no discernible effect on the number of hurricanes. Warming seems likely to have some effect on their intensity, says the current science, but the effect is not yet strong enough to be statistically detectable in the minority of hurricanes that make landfall in the United States. Far more important than climate change in driving the human and material costs of hurricanes like Katrina is where you put houses and businesses, and how you protect low-lying coastal areas against severe weather that would be happening regardless of global warming. The link that activists nudge people to make between global warming and hurricanes has some foundation, but the implied connection is not the whole truth—and it conspires against thinking wisely about reducing future harm.
Alarm over rising sea levels is a similar case. Predicting sea level is especially difficult. Most current projections are for relatively small increases, with regional variations, between now and 2100. Catastrophic rises in sea level could result if the West Antarctic and Greenland ice sheets were to start melting, but most scientists think that for the rest of this century this is a very low order of risk. (The West Antarctic Ice Sheet is the more vulnerable of the two; even after it began adding significantly to sea level, it would take thousands of years to disappear.)
Another fear is that the Gulf Stream, which keeps Northern Europe warmer than it would otherwise be, might collapse. Global warming is likely to weaken its circulation, but if it were to stop altogether, minimum winter temperatures in Britain, for instance, would drop sharply, doing more harm than the projected warming that would happen otherwise. Again, the current consensus is that the Gulf Stream will lessen in strength during the course of this century, but not collapse.
It does not hurt the activists' cause if people think that such a thing is imminent, or if they fear our cities are about to be inundated, or believe that global warming is to blame for every strong hurricane. Some activists insist that science entirely justifies such alarm. Others, more honestly, will say that it is justified as a matter of politics. This is the only way to get anything done: No politician ever won an argument by understating his case.
Given the failure of Congress and the Bush administration to come to grips with this issue, their attitude is understandable. But the question is, once you have persuaded people to panic, how do you get from there to good policy?
We know what has happened to the climate so far, and (with a good degree of confidence) we know why. Working out what is going to happen to it from now on is much more difficult. And that makes judging policy especially hard—especially when you understand that the costs of ambitious front-loaded carbon abatement programs (such as the Kyoto Protocol, fully implemented) would have had (a) only a modest impact on our climate prospects, according to the current models, and (b) enormous economic costs. Yes, something must be done—but need it be as costly and as ineffective as that?
Facing such huge but distant risks, the crucial thing is to think long term, the very thing that Washington does worst. An initially moderate carbon tax, an initially gentle scheme of mandatory caps on greenhouse-gas emissions, and an honest plan to promote long-term energy efficiency could nudge the economy with minimal disruption on to a path of much lower climate-change risk. At the same time—anathema to many environmentalists—serious thought should be given to policies for adapting to climate change. Whatever happens, we will have to live with higher temperatures. And, above and beyond the warming that is already, so to speak, in the pipeline, it will make sense to tolerate some more, and adapt to it, rather than aim or hope to stop it altogether.
Al Gore's movie is not intended to make people think that way. But if it forces politicians, at last, to think at all about the issue, that might be sufficient justification.