President Obama is preparing to give California the green light to start enforcing restrictive new emissions rules that exceed federal standards, and at the same time is calling on the Transportation Department to tighten automotive fuel-economy requirements. It’s no surprise that Obama would move quickly to fulfill these campaign promises, and it is clear that the president desires to impose even more far-reaching environmental regulations. It is also clear that neither of these initiatives will do much to assuage legitimate concerns about global warming, and that the California decision in particular is likely to prove both expensive and fruitless.

The call for tighter fuel-economy standards was mostly political theater. New standards already are required under the Energy Independence and Security Act signed by President Bush in 2007, and Obama called for nothing more than imposition of the law’s existing requirements: a 40 percent increase in the federally imposed “corporate average fuel economy” (CAFE) standards by 2020.

Furthering California’s ambition to act as a freelance climate cop is more significant. The Bush administration had ample legal basis to deny California’s request to enact its own more demanding standards, but the Obama administration has comparable legal authority to reverse course. The timing is clumsy: This would hardly seem the apt moment to impose expensive new regulatory burdens on America’s struggling automakers. Even assuming that manufacturers would be able to pass on these new costs to consumers during ordinary times, there is scant reason to believe consumers will swallow higher prices while unemployment grows and credit shrinks.

Allowing the Golden State to impose greenhouse-gas controls on new motor vehicles will inflict significant economic pain for almost no environmental gain. The economic costs of the mandate are likely to be spread across the nation, particularly if (as promised) 13 other states adopt the new California rules as their own. But even under the most optimistic assumptions, requiring modest greenhouse-gas emission reductions from new cars and trucks will have no appreciable effect on projected global warming. Even if (as some hope, and others fear) California’s regulations become de facto national standards, only a small fraction of U.S. emissions will be affected, and those not for a long time. But California regulators will bask in green glory as the first to impose regulatory limits on greenhouse-gas emissions at the state level.

If President Obama and his advisers are to be believed, this is only the beginning. Fear of global warming made an appearance in his inaugural address and, at last check, the so-called stimulus package was loaded with meretricious energy-related spending. The EPA is also gearing up to impose new regulations of its own. In a memo to agency staff, new EPA chief Lisa Jackson promised to give her “personal attention” to the drafting of “strong, science-based climate legislation” and regulatory measures “to comply with Supreme Court’s decision recognizing EPA’s obligation to address climate change under the Clean Air Act.”

If there’s a silver lining to be found in Obama’s announcement, it will be a newly discovered appreciation for federalism, at least in environmental policy. The merits of California’s ambition aside, there is ample reason to offer state agencies more leeway in developing environmental policies that meet the needs and concerns of their people, without federal interference. Ideally, this would include efforts either to tighten environmental standards, or, when appropriate, to loosen them, directing energy and resources at other equally pressing needs. A consistent regard for federalism from this administration would be a breath of fresh air. But we’re not holding ours.