Greenhouse gases are officially a threat to public health and the environment in the eyes of the federal government. Yesterday, the U.S. Environmental Protection Agency (EPA) finalized its endangerment finding for greenhouse gases. The finding will now compel the agency to regulate emissions under the Clean Air Act.

What a difference a year makes. The Bush administration spent eight years delaying regulatory action on climate-changing greenhouse gas emissions. It sealed its legacy when it finalized a rule in November 2008 forbidding warming from being considered in the development of endangered species regulations. (That decision has since been overturned.)

Now, EPA will move on to the meat and potatoes of greenhouse gas regulations: vehicle emissions limits and standards for stationary sources. EPA has already proposed versions of both rules.

Also yesterday, EPA and other federal departments and agencies released the fall version of their Unified Agenda of Regulatory and Deregulatory Actions, the semiannual plan laying out timetables for upcoming rulemakings. EPA says it will finalize the vehicles standard, which it is developing in tandem with a Department of Transportation rule to strengthen fuel efficiency standards, in March 2010. (Strangely, DOT projects its rule will be finished in April 2010, though I’m sure they will be finalized concurrently.) EPA projects it will finalize its stationary source standards – the so-called “tailoring” rule which would craft emissions limits to apply only to large facilities – in April 2010.