Unilateral EPA regulation of motor vehicle [greenhouse gas] emissions could also weaken U. S. efforts to persuade developing countries to reduce the [greenhouse gas] intensity of their economies. Considering the large populations and growing economies of some developing countries, increases in their [greenhouse gas] emissions could quickly overwhelm the effects of [greenhouse gas] reduction measures in developed countries. Any potential benefit of EPA regulation could be lost to the extent other nations decided to let their emissions significantly increase in view of U. S. emissions reductions. Unavoidably, climate change raises important foreign policy issues, and it is the President's prerogative to address them.Huh? Taking action ourselves on global warming would hurt our standing to convince developing countries to do the same? Talk about political Bizarro-world!
Aside from that, the funny part is how the EPA should have a reasonable case, namely that Massachusetts's requests make little sense. A key point about carbon emissions, one that the Supreme Court fails to note, is that they're proportional to gasoline consumption. This differentiates them from most other pollutants, which arise as unnecessary byproducts of combustion and can be remedied by better technology. Automobile carbon emissions can be cut, but only insofar as fuel efficiency is raised in general.
And Congress already has rules specifically mandating fuel efficiency! I don't think these rules are sufficient; in fact, I believe that global warming should be combated with a more serious solution, like a carbon tax. But as a matter of jurisprudence, it's clear that the only possible regulatory approach to cutting vehicular carbon emissions has been implemented by Congress, and surely it is not reasonable to mandate that the EPA (a non-lawmaking body) periodically alter Congress's legislated policy.
On the case itself, then, this puts me in strange agreement with Scalia, although not with the massacre of science he calls a dissent. But looking beyond this particular case, I think the misunderstanding in the majority's reasoning is very important, and in most cases makes people underestimate how dangerous global warming is. If carbon emissions were like lead emissions, or most of the other environmental threats we've faced, there would be an easy fix -- update the technology and eliminate the problem. Greenhouse gases, unfortunately, proceed inevitably from the burning of fossil fuels, and will demand a much greater change than any we've ever managed.