the relationship between CO2 emissions and temperature was not quite so clear-cut as is made out?

Nothing in the above post was intended to suggest that the relationship between CO2 and temperature was simple or clear-cut. It’s not. But that doesn’t mean that the basic conclusion, that higher CO2 levels means a hotter planet, is wrong.

Wha if the CO2 emissions of India and China would start levelling out in 10 years (like the West)?

They almost certainly will, actually. Carbon efficiency will improve as their economic growth slows (and, IMO, it will as a result of social factors if not global economic factors). But if the models are accurate (and every day brings new proof that they are generally accurate, although certainly not perfect – check out many of the Weekly Carboholics for more details), then leveling out isn’t enough – radical cuts are likely required.

What if there are other variables in the equation?

There certainly are other variables. Aerosols, the water cycle, terrestrial geologic uptake of carbon dioxide, volcanism, the recent lack of sunspots and slow solar wind, methane hydrates, permafrost melting, albedo changes, and so on. They’re all other variables, and the latest climate models all try to include them or at least estimate them. And the estimates are improving all the time.

What if concentrations of CO2 do not affect temperature linearly (that is, there is a “diminishing returns” effect)?

There is some, and again, the models try to account for this information.

how harmful could it be to continue adding costs to production that perhaps do not have the effect that is claimed (or are not actually necessary)?

Damn good question, and one I struggle with a great deal.

Oh, and if carbon emissions have exceeded the initial “worst-case” scenarios of the IPCC, why has temperature not increased over the past 10 years?

1998 was an el Nino year, so it was extra hot. 2008 is a la Nina year, so it’s extra cold. Take out the effects of el Nino and la Nina and global temperature has continued to increase over the last 10 years (great graph of this exact thing is here). Additionally, 10 years isn’t enough to make a strong statistical argument about trends in temperature. Even 15 years is questionable. And all the long-term trends that are statistically meaningful still show an increase.

In the current economic crisis, how harmful could it be to continue adding costs to production that perhaps do not have the effect that is claimed (or are not actually necessary)?

Oh, and if carbon emissions have exceeded the initial “worst-case” scenarios of the IPCC, why has temperature not increased over the past 10 years? Do we really think that a 1.3 degree temperature rise in the 20th century will be followed by an 11 degree rise in this century?

Though the two Asian titans (China and India) are horrific polluters, there is no question that they’re focused on going green. China is investing more than just about anyone in renewables, even while they keep building new coal plants. At a micro level, it is much easier to green the daily life of an Indian household than an American one. When the house doesn’t have electricity to begin with, it makes more sense to put up a solar panel that will charge a mobile and run some LED lights than it does to build complicated infrastructure to get the juice from the new coal plant to the house.

I would not be surprised to see a leap frogging of the West by China and India when it comes to going green. And i would not be surprised to see it happen fairly soon. China’s economy is slowing…partially because America’s economy is slowing and partially because the deep pool of cheap labor is starting to run dry. The Chinese can’t afford to have a large pool of unemployed, but they can afford to invest massive sums into public works.

But don’t expect them to change their public tune when America tells them to clean up their act. They won’t be bullied, especially for the sake of America shirking its blame/duty. Look at how they deal with Europeans on these issues, as it is a much different relationship…perhaps because when Europe talks about the environment it doesn’t sound so hypocritical.

But most of all, we should be in the lead on these matters rather than behaving like a sullen teenager. And we’ll have to learn that you can’t tell your banker what to do…especially if you want to ask him for $700B.