Meanwhile, about 40 percent of U.S. carbon emissions come from power plants, and coal-burning plants produce far more emissions than do facilities that use other fuels — more than twice as much, per unit of electricity generated, than plants burning natural gas, for example.

Low prices for natural gas have caused utilities to switch fuels. Ten years ago, according to the Energy Information Administration, half of the nation’s electricity came from coal-fired plants and less than one-fifth from plants burning natural gas. Last year, just 37 percent was generated by coal — and about 30 percent by natural gas.

Obama has the opportunity to cut carbon emissions by hastening a transition already under way — without action by the hostile Republican majority in the House or the nervous Democratic majority in the Senate.

The Environmental Protection Agency has the power — I’d call it a duty — to issue rules limiting carbon emissions per unit of electricity generated. Tough, science-based rulemaking would give utilities an incentive to switch from coal to gas — and effectively guarantee that no new coal-fired plants would be built.