No, it doesn’t. Exponential growth makes the Doomsday conclusion more dramatic, but the logic of the argument is independent of it. See Bostrom for more on this point.

Yet you think we should impose Kyoto, because it might lead to later effective reforms. I would love to see you attempt some kind of cost-benefit analysis to justify that position. I’d also like to see (before we spend what may turn out to be a trillion $ if it later turns out Lomborg is right or may turn out to be 10 trillion $ if Lomborg left out some important costs, such as additional hidden costs to the economy coming from governments’ asserting additional control in order to implement Kyoto or worse protocols) some proposal of what your later effective reforms might look like, and what their cost benefit analysis might be.

Absent a rational proposal of why Kyoto would be cost-effective and what realistically could be accomplished, support for it has the aura of being religiously motivated:
mankind has sinned and must atone, independent of whether making the appropriate sacrifices has any actual effect, and maybe the more it costs, the better the sacrifice.

Incidentally, I highly recomment Lomborg’s reply to Scientific American.
Lomborg
Lomborg’s rebuttal makes quite clear that the various critiques of his book by highly respected academics published in Sci Am, while extremely tendentious in tone, don’t even challenge his main conclusions. They just throw heat on the subject in an attempt to obscure the issue. I find it quite illuminating from a sociological perspective. Its very positive, in my view, that while (unfortunately) politicized scientists are willing to make all kinds of rash and unsupported statements to the press, they mostly remain unwilling to publish such things, even in places like scientific american (hence the divide between their published papers, from which Lomborg extracted his book, and their sciam comments which have to resort to obfuscation rather than admitting that Lomborg has summarized the situation.)

I don’t agree with Lomborg’s cost estimates (again, something to blog about later), but I completely agree that the Kyoto protocol would be only a small beginning. But look, if you’re driving full speed toward the edge a cliff, tapping the brake slightly is better than doing nothing. At least your foot is over the brake now, so you’re in a better position to slam it when it becomes apparent to everyone in the car that there’s no other option…

In fact, most populations do *not* grow exponentially, but rather go through a phase of exponential growth but then asymptotically approach a stable population as they become resource limited.

As far as I understand, given the falling birthrate around the world, the human population looks to stablize in the foreseeable future.

This has little to do with global warming (except as an example that conclusions arrived at with a unsound model are themselves unsound), but I’m amazed that no one else pointed it out.

as it happens the day after your post (May 3) Lubos Motl has a post of simulations from a computer program demonstrating
“that the reconstructions that imply that the 20th century climate was unprecedented are as statistically trustworthy as sequences of random numbers.”
Motl

On the question: “Suppose I accepted (which I don’t) that the probability of an anthropogenic climate disaster was only 25%. Wouldn’t that already justify a major policy response?”

The answer to that is, depends on a cost benefit analysis. For example, even if the models were proven to be 100% accurate, with human caused global warming a certainty, the Kyoto protocols would make no sense whatsoever, because the gain, according to the models, (and assuming even that all the countries actually kept to the emissions goals, which has already proven to be a pipe dream) would be not to prevent global warming, but to delay the warming by a grand total of 6 years over the next century. Achieving this would however cost a trillion $, 5 times the cost of global sanitation and clean water Lomborg article

On the subject of name signing, I wonder if you saw Lindzen’s article in the WSJ a week or so ago, which listed various scientists who were punished for dissenting from the global warming chorus. Lindzen Op-Ed
The fact is, making leftist noises is regarded within academia as showing ones credentials as members of the club and rewarded, whereas conservative comments are often punished.

Have you looked into what McIntyre and McKitrick’s “debunking” of the Mann et al. hockey stick actually consists of? When I did (in response to another climate skeptic who brought it up), I could barely believe it. All they’re saying is that, if you do principal components analysis on random temperature data, you’ll get some component that looks like a hockey stick. Well, duh!! The point is that the magnitude of the hockey stick component in the actual temperature data is bigger than chance at something like a 5-sigma level. Yet, from this one doofus statistical error, the claim got repeated from op-ed column to another that “the hockey stick has been debunked.”

You say it’s “not completely irrelevant” to note the financial interest of the scientists involved. My favorite answer to that was given on RealClimate: if you wanted more funding for climate research, you would emphasize the uncertainties in the science, not the certainties! Also, it’s conceivable that Exxon, Texaco, etc. might have a financial stake as well, though I’ll concede it’s more likely that they, unlike the scientists, are solely motivated by the rigors of intellectual honesty.

Suppose I accepted (which I don’t) that the probability of an anthropogenic climate disaster was only 25%. Wouldn’t that already justify a major policy response? What if we were talking about a 25% chance of nuclear war? Somehow, in the minds of the climate contrarians, 25% quickly becomes 5% becomes something like 0%.

I’ll try to answer some of your other “talking points” in future posts. Let me close with this observation: I think a reasonable observer would find your feelings on the subject every bit as “religious” as mine. But only one of us is willing to sign his name.

normally I appreciate your posts, but this one is just looney, reflecting the religious nature of your feelings regarding global warming. The reason why many rational people are skeptical about human caused global warming isn’t connected to any of the absurd things in this post, it’s that there’s little evidence for it.

The people who feel like you are typically fond of citing the supposed “scientific consensus”, but what the IPCC 2001 report stated was not that human cause of global warming is an established fact, but rather
that there was > 2/3 chance greenhouse gasses had caused a substantial fraction of global warming. Even this degree of confidence was controversial rather than consensual, as witness the fact that it was beefed up from the draft report.
I doubt any of the skeptics would say there was less than 1/4 chance humans had contributed significantly to GW (most if not all skeptics agree that humans have increased CO2, and argue not that we understand the physics well enough to say this has no effect, but rather that we don’t understand it well enough to say it will cause massive warming) so the argument is over probabilities, not certainties.

Moreover the IPCC 2001 “consensus” was mostly based on the hockey stick, which at the time was regarded as fact, but is now, to be tactful, at best in limbo.

Its also not completely irrelevant to note that the climate scientists, not to mention politicians, have substantial financial interest in finding a human caused climate catastrophe.

My own view is that there’s significant evidence of a little Ice Age in Shakespeare’s time, so its hardly surprising, or alarming, that the world has warmed a bit since. The recent move is well within the noise of natural climate moves over the earth’s history, so well within that there’s no reason to be surprised it occured exactly now. The climate models may be based on 19th century physics, as you say, but that’s not exactly an endorsement. They make zero
predictions, and didn’t bat an eye when factor of 10 effects such as heat absorption in clouds were suddenly discovered in the late 90′s and introduced into the models. (In fact, so little fuss was made about the fact that the models absorbed a suddenly discovered effect
that was a factor of 10 larger than any alleged CO2 greenhouse effect without any change in their predictions, only some parameter retuning, that I suspect you were unaware of it.) In short, humans may be having an impact, or they may not,
I guess I’d lean towards the less than 50% school, but its not an established
fact like Al Gore would have you believe.

As to your complaint that we’re not discussing your arguments, one problem is that the post was about a class of arguments you wanted to avoid.

Anonymous:
(a) act in such a way that (we believe) if everyone else acted in that way then our problems would eventually be solved.

Aside from the obvious problem that not not everyone else is going to act like you, what does that mean? Be rich enough to afford a hybrid? It is far more effective to do things to lower the price of hybrids than to buy them now.

One thing about hybrids, unlike other worthless rituals environmentalists do, is that you can put a dollar amount on them. The owner of a hybrid has said he’s willing to make that size sacrifice. Unfortunately, it’s usually too late to convince him to use it differently. But, Scott could advise those influenced by his car to come up with a more effective use of their money.

(a) act in such a way that (we believe) if everyone else acted in that way then our problems would eventually be solved.

(b) spread the message whenever it’s convenient.

As bad as it could get, global climate change hasn’t annexed Austria and Czechoslovakia yet, so I don’t yet feel compelled to ruin my life for the cause.

It’s conceivable that buying a Prius wasn’t a step in the direction of absolute steepest ascent in the utility function induced by your unique skill set, but it’s still a step in the right direction. At least you didn’t buy a Hummer with a bumper sticker that says, “support our troops.”

Also, kudos for incorporating metareasoning into a post about global climate change instead of pretending to be a climate scientist.

Gus