I haven't paid nearly enough attention to Mass. v. EPA, the Supreme Court case holding that EPA has the power to regulate greenhouse gases, to have a legal opinion on the merits. I'd be astonished if I wouldn't agree with the minority. But I do wonder about one thing. There is one undisputed contributor to global warming: the reduction in air pollution over the last thirty years. Until this week, "air pollution" largely meant the emission of particulate matter into the atmosphere. Since the Clean Air Act passed in 1970, particulate matter in the air over the United States has decreased by approximately 80%. This reduction is the best established (perhaps the only well-established) example of unambiguous anthropogenic global warming.
Particular matter in the atmosphere raises the Earth's albedo. That is, more of the heat and light hitting Earth is reflected back into space if there is more particulate matter in the atmosphere. In fact, one suggestion for dealing with global warming is to release a relatively small amount of particulates directly into the stratosphere in jet fuel exhaust. Necessarily, reducing particulate matter over the last 30 years has lowered Earth's albedo, allowed the Earth to absorb more heat from the Sun and made the Earth warmer, caterus parebus, than it would otherwise be.
So, thanks to the Supreme Court, one of EPA's missions necessarily works counter to another of its missions. One wouldn't think, in the first instance, that it was the Court's role to balance contradictory policy aims. Too bad that Congress is too busy setting up its own foreign policy to deal with domestic issues.