The Supreme Court’s ruling Monday to uphold the Environmental Protection Agency’s ability to regulate greenhouse-gas emissions is a great development for those interested in delaying the potentially catastrophic effects of climate change [“Justices: EPA can regulate emissions,’’ front page, June 24].

The regulations themselves, however, could have a negative economic effect. This is the problem of pursuing what economists call “second-best” solutions. The optimal solution would, of course, be a carbon tax that requires greenhouse-gas producers to pay in proportion to what they emit. As opposed to regulations, which can be complex and often treat disparate enterprises equally, a carbon tax is easily understood and effective regardless of the size or sector of the emitter.

The benefits of the EPA regulations stem not from their economic efficiency but from their potential to make members of Congress finally address the reality of climate change. Hopefully, Congress will now be able to pass legislation that makes greenhouse-gas emitters pay for the entire social cost of their production in the most economically efficient way possible: with a carbon tax.

Ethan Rutledge, Washington

I read Cara Smith’s June 22 Local Opinions commentary, “Clearing the air in Maryland,” with a mixture of sadness and validation. A volunteer with Citizens’ Climate Lobby, I, too, have noticed that air quality has worsened in my lifetime.

A simple, elegant solution to this problem would be an across-the-board carbon tax. With revenue from the tax returned to U.S. households, price increases would be manageable. By gradually increasing the tax every year, the economy would have time to adjust and shift incentives for how we create electricity, and clean technologies would grow out of a free market.

Already economists from conservative and liberal camps agree that it’s the best answer.

Tamara Kellogg, Washington