I put this in the comments of an earlier thread, but I thought worth highlighting as well. What are potential effects of EPA regulation of carbon dioxide from automobiles?

Taking a look at data from the US EIA (here):

It projects out to 2030 that the accumulated global carbon dioxide emissions will be 235 GtC. It also projects that of this total about 15 GtC will come from the use of petroleum in the United States. Let’s assume all of this comes from cars. Lets further assume the EPA regulates carbon dioxide such that no emissions are allowed.

This would reduce the global total emissions of carbon dioxide from 235 to 220 GtC by 2030 (assuming regulations start January 1, 2007). (The ratio presumably gets smaller further into the future as global emissions are projected t increase faster than US auto emisssions.) I don’t think that current climate models are able to differentate bewteen a world with these two values of carbon dioxide emissions, much less predict how one might be different than another.

In short the effects of EPA regulation would likely be nil. So is the lawsuit about publicity? Compelling U.S. participation in an international agreement? Because it sure does not look like it is about reducing the impacts of carbon dioxide on anything perceptible in the United States.

What have I missed?