First, there is Larry Summers.

Those who still deny that human activity is warming the planet, or claim that “business as usual” can continue indefinitely without profoundly adverse consequences, are increasingly seen as the moral and intellectual equivalent of those who deny that tobacco has adverse consequences for human health.

…The limited impact of Kyoto is evinced by the fact that carbon permits are now selling in the range of a negligible one euro a tonne.

…carbon markets are invitations to engage in pork-barrel corporate subsidy politics on a massive scale.

He promises a future column, where I’m betting he’ll embrace the Pigou Club.

But I think it’s time to fight back against the tobacco analogy. It is not the scientific consensus that makes me believe that there is a link between smoking and cancer. It is the evidence for such a link that is compelling. It is the weakness of the evidence of the link between man-made carbon dioxide and climate change that makes the scientific consensus less persuasive than the tobacco-cancer link.

In the spirit of trying to examine the evidence, last evening I attended this event, sponsored by the World Affairs Council of DC.Michael MacCracken was the spokesman for the scientific consensus. He is the sort who believes that only scientists like himself are qualified to discuss the issue. His attitude was one of someone forced to share a panel with a bunch of wingnuts. His contempt for other points of view extended to those who think that carbon taxes are the best policy option. Evidently, the scientific consensus is that command-and-control is better, although he did not use that term.

During the question period, I asked about climate engineering, and I pointed out that the Stern report was implicitly calling for a sacrifice of $500 billion per year. McCracken described climate engineering ideas, and he made them sound outlandish, so presumably very costly. But he never came back to the issue of comparing that cost to $500 billion a year.

Reason Magazine‘s Ron Bailey embraced the Pigou Club, although not by name. Not surprisingly, I found his talk the most sensible.

Marlo Lewis of the Competitive Enterprise Institute took the anti-alarmist view. I thought his best point was when he noted that Fred Pearce’s book talks about the catastrophic effects of ice melting by describing the sea level rise that took place when the last ice age ended. Lewis pointed out that there was a lot more ice to melt back in those days. Overall, though, Lewis came across as taking random swipes at the consensus rather than making a coherent case for his point of view.

Pearce himself said, and I agree, that skepticism about climate models should increase one’s concern about both tails. That is, the models may under-predict global warming. In fact, that is my number one concern with the issue. His book, which I bought, is a litany of potential disaster scenarios, from peat bogs dissolving and releasing massive amounts of methane to ice sheets quickly breaking loose into the ocean. Even though these scenarios are not in the scientific consensus represented by Dr. McCracken, I think they are the right things to worry about.

Finally, Fred Singer attacked the climate models. His toughest criticism concerned the models’ predictions about specific warming patterns in terms of altitude and latitude. He said that the models predicted one pattern, and the data showed a different pattern. McCracken replied that the temperature readings by altitude and latitude were not reliable–which didn’t exactly increase my confidence in climate science. Singer also pointed out that one of the leading models forecasts that North Dakota will become a swamp, and another leading model forecasts that it will be a desert. McCracken responded that models are highly non-linear, and small differences can lead to very different results. Again, not exactly a reassuring answer.

Several speakers made self-contradictory statements. For example, Singer said that correlation is not causation, and then later he proudly displayed a chart showing the high correlation between cosmic ray activity from the sun and global temperature. Pearce mocked those who would doubt the scientific consensus for acting as if that consensus were some sort of vast conspiracy, but then his whole outlook is geared toward views that are outside the mainstream.

My sense is that many people in the audience came in with strong views about global warming–one way or the other. My sense is that people left with the same views that they held going in. That is somewhat frustrating. But I plead guilty as anyone else of suffering from confirmation bias. I continue to hold the views I expressed here.