A random courthouse photographed from a dramatic angle.

This morning, a federal appeals court in Washington, D.C., upheld the Environmental Protection Agency’s (EPA) first-of-its-kind greenhouse gas regulations, dismissing out of hand a variety of challenges from industry and states. The findings uphold the agency’s rules defining limits to the emission of greenhouse gas pollution under the Clean Air Act. Specifically, the court ruled: Yes, the agency acted properly in determining that CO2 is a danger to public health; yes, it was right to use that determination to regulate vehicles; and yes, it was within its authority to determine the timing (Timing Rule) and scope (Tailoring Rule) of the regulations.

The Wall Street Journal called the decisions “a blow to an array of industry groups”; Politico declared them “a surprisingly sweeping win.” In short: very good news.

Here’s how the U.S. Court of Appeals for the District of Columbia Circuit decided. (At the bottom of this post, you can read the decision itself, via FuelFix.)

1. The Court determined that the EPA absolutely has authority to regulate greenhouse gases as a pollutant.

The genesis of this litigation came in 2007, when the Supreme Court held in Massachusetts v. EPA that greenhouse gases “unambiguous[ly]” may be regulated as an “air pollutant” under the Clean Air Act (“CAA”). Squarely rejecting the contention — then advanced by EPA — that “greenhouse gases cannot be ‘air pollutants’ within the meaning of the Act,” the Court held that the CAA’s definition of “air pollutant” “embraces all airborne compounds of whatever stripe.”

In other words, when the Bush administration EPA was sued by the state of Massachusetts in 2007 for not regulating greenhouse gases, the Supreme Court determined that it unquestionably had the authority to do so. A pollutant is a pollutant, after all, regardless of impact.

2. Even if there were uncertainty about climate science — the argument advanced by the petitioners — the entire point of the EPA regulations is to be proactive in addressing problems.

[T]hey contend that the record evidences too much uncertainty to support that judgment. But the existence of some uncertainty does not, without more, warrant invalidation of an endangerment finding. If a statute is “precautionary in nature” and “designed to protect the public health,” and the relevant evidence is “difficult to come by, uncertain, or conflicting because it is on the frontiers of scientific knowledge,” EPA need not provide “rigorous step-by-step proof of cause and effect” to support an endangerment finding. As we have stated before, “Awaiting certainty will often allow for only reactive, not preventive, regulation.”

3. Anyway, the EPA’s science on impact is well-reasoned and thorough.

The Court walks through the EPA’s various scientific findings and studies in some detail, noting that “Industry Petitioners do not find fault with much of the substantial record EPA amassed in support of the Endangerment Finding.”

To recap, EPA had before it substantial record evidence that anthropogenic emissions of greenhouse gases “very likely” caused warming of the climate over the last several decades. EPA further had evidence of current and future effects of this warming on public health and welfare. Relying again upon substantial scientific evidence, EPA determined that anthropogenically induced climate change threatens both public health and public welfare. It found that extreme weather events, changes in air quality, increases in food- and water-borne pathogens, and increases in temperatures are likely to have adverse health effects.

In closing, the court writes:

For the foregoing reasons, we dismiss all petitions for review of the Timing and Tailoring Rules, and deny the remainder of the petitions.

So ordered.

In the vernacular: Ya burnt.

Now the chastened polluting industries will quietly upgrade their systems to reduce greenhouse emissions, and we’ll never speak of this again.

Just kidding. See you at the Supreme Court.