Goldberg asks about what environmentalists would do if the global warming seen since ~1900 were natural and not anthropogenic:
If Al Gore were to be convinced that global warming WAS a natural phenomena, would he be so worked up about it? I don't think so, yet the consequences would be the same.Roberts replies:
If global warming is anthropogenic, we need to both stop exacerbating it and start adapting to the effects that are already inevitable. If it is natural, then we only need to adapt, since apparently nothing we do can affect the natural course of climate changes. OK?That's exactly wrong. Atmospheric physics does not change if the last 30 years of warming have been natural. The potential for carbon dioxide to heat the atmosphere is still the same, and we're still pumping it into the sky. Climate models still have the same validity they do today if the last 30 years of warming were natural. We'd still need to be just as concerned about the potential for ~3°C warming by 2100 due to the greenhouse gases we're putting into the atmosphere. In fact, if the last 100 years of warming were natural, we're even in worse shape, because we're pumping heat-generating gases into the atmosphere on top of a natural bubble.
So whether the last 30 years of warming, or even the 20th century's warming, are natural or not, we still have a big problem and we still need to find alternative ways to generate our energy. It's the physics of the situation that is the big problem, not the explanation for past warming.
UPDATE 7/7/06: William Connolley thinks I missed the main point: if global warming "is natural, there is no reason to expect it to continue." If by saying recent global warming is natural Jonah Goldberg is implying that CO2 has no heat-trapping ability (as David Roberts points out in the comments here), then I think I misinterpreted this. Or maybe he means that CO2 does trap heat but it just hasn't trapped much yet. If he doesn't think CO2 traps heat, I'd like him to explain why the earth isn't a frozen ball at 0°C instead of a relatively balmy ball at 14°C. I like to know what his calculations show for the climate sensitivity.