Last month, executives from six of the country’s largest energy companies made a startling request to federal lawmakers: Set mandatory caps on greenhouse gas emissions.

At an April 4 climate conference held by New Mexico Sens. Pete Domenici, R, and Jeff Bingaman, D, the leaders of Shell, General Electric and others said they would prefer uniform federal regulation to a patchwork of emissions rules like those proposed by California and eight New England states (HCN, 3/6/06: States tighten rules, challenge feds to follow). Federal regulation would not pre-empt those plans, which are so far stricter than any congressional proposal. But the corporations hope that other states would follow the feds’ lead instead of acting on their own.

The corporations’ new tone could press federal lawmakers into action, says David Doniger, policy director for the Natural Resource Defense Council’s Climate Center: "This will be looked back on as a watershed moment."

Yet even representatives who support climate legislation still don’t agree on how strict the emissions caps should be, says Marnie Funk, Republican spokeswoman for the Senate Energy and Natural Resources Committee. She cites the McCain-Lieberman Climate Stewardship Act, which has languished in Congress for three years.

That legislation includes a "cap and trade" program for greenhouse gases. Sens. Domenici and Bingaman plan to include a similar program in a new climate bill, but neither wants to introduce the bill within the next year, fearing that it, too, will be shot down.

Late last year, a National Academy of Sciences report predicted that impacts to the economy and environment will be more costly the longer emissions go unchecked.