The climate challenge just became a lot more challenging. We know that man-made carbon dioxide emissions are accelerating global warming. But intrepid research has revealed an additional sinister threat: methane. As Sarah Simpson reports, the warming of the Arctic is releasing vast quantities of methane that has been locked away for centuries in formerly frozen soil. Once released, methane traps 25 times more heat in the atmosphere than carbon dioxide does. So it is more imperative than ever to slash greenhouse gases quickly, to slow the venting of methane.

The single boldest stroke must come from Congress. The House and Senate are debating legislation that would impose either a cap-and-trade system or a tax on carbon emissions (for updates see Certain politicians and CEOs are trying to talk Congress out of it. Our representatives should dismiss the detractors and pass legislation, before November. That deadline is crucial: nations will meet in December in Copenhagen to hammer out new international agreements to limit emissions. The U.S., shamefully, has never signed such a protocol, and leaders worldwide have said, plainly, that the Copenhagen talks will fail if the U.S. does not enact legislation to clean up its own backyard.

Another bold stroke would be to confront the 800-pound gorilla in the room: population. Cutting our wanton consumption will reduce emissions in the short term, but sustaining our planet long-term will depend on how fast population grows. It’s a touchy subject, but we have to face it. Robert Engleman lays out the issues in his article on population and sustainability.

Hope lies in action. Let’s embrace what forward-thinking economists are saying, that putting a cap or tax on carbon will stimulate massive innovation in the next great global industry: clean energy technology. Even a slowly growing population will create big demand for clean energy, and the U.S. can build a new economy by dominating this market—but only if it acts boldly, before other nations do.

Note: This article was originally printed with the title, "Needed: Bold Strokes. Now."