I tried to close the comment argument with Chris below, and actually liked what I'd written enough that I thought I'd promote it (slightly cleaned up) to a post...
If you're thinking that AGW will be conclusively proved or disproved in blogs you've got bigger issues than I can help you with.
What blogs can - and I believe have - done is to suggest that the emperor has no clothes. There's a world of difference between pointing out that standard accounting practices haven't been followed - and therefore we ought to recheck the books - and actually re-auditing GM's annual financial statement. It's unfair and unreasonable to suggest that people who point out a) also have a responsibility to do b), or the current books stand.
I do think that people are deluding themselves by suggesting that AGW is 'science' as we've practiced it for the last few centuries. There's an epistic problem that comes from the fact that AGW is inherently a wicked problem - we can't run global climates in labs, over and over again and check what happens in the empirical world. There's no empiricism there.
Instead we run computer models.
Now in a century, to be sure, we'll be able to validate (or invalidate) the predictive power of those models.
Until then, they are exercises in quant 'science', which is likely to be as successful as quant 'finance' was for LTCM, Bear Stearns, Lehman, et alia in the last decade.
Both work well in limited domains (what Taleb calls 'mediocrestan') and fail catastrophically outside them.
In my view, science is empirically reproduceable. Feynman said (I think it's in the Lectures) "The test of all knowledge is experiment. Experiment is the sole judge of scientific 'truth'." Anything that isn't empirically reproduceable - isn't really science.
When AGW advocates start running reproduceable experiments, let us all know. For now, I'd even settle for reproduceable base data.
That's pretty much all I have on this. You're welcome to respond, advocate, cavort, or whatever in response.
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As a basic statement of what science must be, it's very hard to argue with this. And anyone trying would arouse my deep distrust.
Human affairs, it should be noted, are not a science and never will be - the puffery of "social sciences" departments to the contrary falls into the "doth protest too much" category.
If so-called science becomes politics, it descends to that level and ceases to deserve the respect that real science has earned for itself.
Bingo.
While I agree with the sentiment, I have to say that rigorous adherence to reproducibility of experiments (as opposed to models) pretty much rules out fields such as modern astronomy, nuclear weapon design, evolution theory, particle discovery, etc.
Lots of reality just doesn't allow us to run experiments on it.
Of course anyone who is claiming P(AGW)=1 is either silly or, more likely, realizes that because of the politics, such a claim is the only way to get anyone to consider acting upon it seriously.
Tom, you're right that nuclear weapons design today is entirely model-based, which is worrisome.
But evolution is subject to experimentation, the LHC (as an example) was built so that particle physicists could do - experimentation.
And while experimentation in astronomy and cosmology is scarce, observation - is kinda important.
So while we're on the same side on what we want, I think that practice in many fields is closer to what makes both of us happy...
Marc