The article by Thomas D. Peterson, Robert B. McKinstry Jr., and John C. Dernbach (PM&D) has two central insights: (1) Any serious national effort to control emissions of greenhouse gases (GHGs) must continue to leave important roles to the states; and (2) It would be a mistake to put too many eggs in the cap-and-trade basket. A portfolio approach that utilizes many different regulatory techniques is important.

I certainly agree with PM&D about these insights, and they are correct that much of the current Congressional debate has given too little attention to these considerations. However, I have serious reservations about PM&D's proposal to use the mechanism of the national ambient air quality standards (NAAQS) and state implementation plans (SIPs) as the way to give states the vital roles they deserve. I believe there are alternative methods that would be superior.