ON TUESDAY, the Environmental Protection Agency announced its first limits on carbon dioxide emissions from new power plants. By requiring that facilities produce less than 1,000 pounds of carbon dioxide per megawatt-hour, the rule essentially bans construction of traditional coal-fired power plants. That’s good: Burning coal releases lots of carbon dioxide and a range of nasty pollutants that encourage heart attacks and respiratory illness.

Yet only by the miserable standards of Congress’s continuing inaction on climate change is this rule impressive. The EPA’s new carbon standards won’t change all that much. Low natural gas prices and the high efficiency of natural gas power plants have already moved the market away from coal and toward that cleaner fossil fuel. Should natural gas prices shoot up, the EPA’s rules guarantee that utilities couldn’t turn back to old coal years down the road, The Post’s Brad Plumer and Grist’s Dave Roberts point out. The rule also provides America some moral authority to pressure other nations to scale back coal burning. But those are modest benefits.

Since the EPA’s standards apply only to new facilities, they won’t affect the worst polluters — decades-old dinosaur coal-power plants that spew a noxious cocktail of chemicals into the air — not to mention other fossil-fuel-power facilities that emit carbon, which the government will have to address eventually. The EPA will have another round of rulemaking for existing plants, but it’s unclear when or how it will set standards.

In establishing those rules, regulators will have to balance the imperatives of clean air with the economic effects of possibly taking more power plants offline or requiring extremely expensive retrofitting. Even ardent environmentalists must admit that it is difficult to draw that line when affordable electricity is the lifeblood of America’s recovering economy. The standards that would make sense now wouldn’t years from now.

A more rational policy would cut pollution across the economy at a low marginal cost with predictable terms and a regular schedule of tightening emissions standards, allowing businesses to factor carbon costs into their decision making. Most economists believe that putting an increasing price on carbon through a carbon tax or a cap-and-trade program is the best way to accomplish those goals. Implementing such a policy would also signal the world that America leads with more than words.

You can’t fault the EPA for not pursuing a more ambitious carbon tax or a cap-and-trade system, though: It’s far from clear it has the statutory authority to do so, even on a sector-by-sector basis. The fault lies with Congress, which has failed to establish anything resembling a comprehensive energy policy. Lawmakers, particularly on the right, seem most politically allergic to the most obvious climate policies. The result is a ramshackle collection of clean-energy subsidies, EPA mandates and state actions that can be both expensive and underwhelming.