Thursday, July 06, 2006

What if GW Were Natural?

David Roberts of Gristmill wades into the swampy debate posed by Jonah Goldberg of the National Review, but I think Roberts comes to exactly the wrong conclusion.

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.

9 comments:

David Roberts said...

David, I'm not sure I follow you. When conservatives Goldberg raise the possibility that global warming is "natural," what they mean is that the amount of CO2 we put into the atmosphere is inconsequential (it's the "urban heat island effect" or the "solar effect" or whatever that's causing warming). I think that's wrong, of course, but if it's true, well, why should we worry about our emissions?

David Appell said...

If that's what Goldberg means--if he really doesn't believe the physics of climate sensitivity--or if he believes them but thinks CO2 just hasn't taken hold yet--then I guess I see your point.

David Roberts said...

What else would conservatives mean when they say climate change is "natural"?

Belette said...

I think you're missing the point: http://scienceblogs.com/stoat/2006/07/what_if_gw_were_natural.php

Adam said...

"what they mean is that the amount of CO2 we put into the atmosphere is inconsequential (it's the "urban heat island effect" or the "solar effect" or whatever that's causing warming)."

The UHI effect is not natural. ;-)

jre said...

I think William has pointed to the centrally goofy quality of the physical hypothesis. It requires what z referred to on Deltoid as "Occam's shaggy beard." OK, our understanding of the radiation physics is all wrong, and sensitivity to additional CO2 is so small that greenhouse forcing may be neglected. But [insert your favorite sinister force here] has a much greater effect than we had guessed (we're such idiots) and more than makes up for the missing greenhouse forcing. Huh?
That's an argument so wacky that I cannot imagine a rational being employing it in good faith; hence, I suspect the motives of anyone who does employ it.
On the cultural side, I'll note that this meme of "environmentalists love anything natural, even if it's bad" seems to be spreading like one more evil stain on the blotchy tablecloth that is the loonosphere. Holman Jenkins, of the loathsome WSJ editorial page, let fly with this cowpie a few months ago:


"A final thought that probably won't please the environmentalists: Whatever the truth of climate change turns out to be, today's vast investment in climate research will likely lead someday to technologies that really will allow us to alter local and global weather."


Aargh. What a ninny. His other stupidities are discussed to death over at RealClimate.

John McCormick said...

So, lets take the natural warming hypothesis one step closer to the edge. Warming does have natural causes.

CO2 emissions have natural causes as well; and also anthropogenic sources, i.e., land use, fossil fuel combustion, intentional burning, etc.

Now, we can sit back and watch the natural warming forces at work while we measure the increasing acidity of the oceans and diminished capacity of oceans to provide sinks for our CO2 contributions to the atmosphere which, I believe (unless atmospheric chemistry science is a fraud) will add to the warming and trigger positive feedback of CO2 and CH4 from melting tundra and permafrost.

Or, am I mising something here?

Anonymous said...

David, what do you mean the "climate models still have the same validity"? The same as what? They can't have the same validity as each other, because they vary by more than a factor of two in climate sensitivity. If GW is natural, then yes, the climate models got it wrong and will have the same invalidity until they are fixed. There is plenty of room for the models to be invalid. The models are not the same as each other. There are several models. While it is obvious that the models can't all be right, remember, it is also possible than none of them are right.

andrew said...

basic stuff
please agw folk answer above question