(No, not involving swimsuits.)

Mark Kleiman runs a political blog I subscribe to with my RSS reader. In response to novelist Michael Crichton's rant that global warming is just bad science, he recently posted a brief but insightful exploration of why, although predictions are usually wrong, thinking about the future -- and, in particular, building models to tell us about how the future may unfold -- is still a useful and important endeavor:

Right, then. We can't know what the world will look like in 2100. But unless we also don't care what the world looks like in 2100, or unless we think our current actions have zero predictable impact on what he world will look like in 2100, we need to make decisions now -- we are, in fact, making decisions now -- in which results a century hence are part of the objective function.

Uncertainty about the results of our actions will indeed suggest that we should discount predicted far-future effects vis-a-vis more predictable near-future effects (this in addition to the normal discounting for the time-value of resources). But not to zero, surely?

In short, as we used to say at the scenario-planning company I worked for in the 1990's, "the future is uncertain -- and yet we must act."

Thanks for pointing this one out... The 'Global Warming' points are what I consider to be true, yet the fact remains that we are affecting our environment, and our environment will continue to affect ourselves - so we need to work toward having a positive impact on the environment. Is it possible? Not in all respects, probably, but it is a Grail. :)

Posted by: Taran on January 2, 2004 2:12 PM

What I find most distressing about this debate is the apparently willful refusal to state the basic fact: global warming is HAPPENING NOW! The evidence for this is irrefutable, with the most obvious signals being the melting of fossil ice from Waterton-Glacier International Peace Park to Kilimanjaro to Antarctic ice shelves.

After this first question is accepted, the second question should be "is this a good thing?" with not much debate over the proper answer: No. I don't know anyone who is in favor of more flooding in sea-level cities like Venice and New Orleans, not to mention Amsterdam. I suppose some people can't comprehend the cost of losing whole ecosystems that can't migrate poleward fast enough, so whether that's bad is irrelevant to them.

The third question, should be "can we do anything about it?" There should be no debate about the fact that anthropogenic carbon dioxide makes some kind of contribution to global warming, but many commentators can't seem to grasp the distinction between "no contribution at all", and "no significant contribution relative to the natural climate cycles." If they could, the debate would be much less polarized.

If we know there is something we can do, but we just don't know how much effect it will have, then cost-benefit analysis is the right method, not ranting about misrepresentation of basic facts and some hyper-rigorous "scientific method". The Kyoto treaty arguably misallocated the costs and benefits, but its failure doesn't mean that we can go back to sleep about the phenomenon and its impact.

Posted by: Alton Naur on January 3, 2004 1:56 PM