Here we are in a new climate--and I'm not just talking about global warming. America is a changed nation, and the Sierra Club is a changed organization. The turning point for both came in the first week of September 2005, when New Orleans drowned and the Sierra Summit opened in San Francisco.

Hurricane Katrina changed the country by putting the callous incompetence of the Bush administration on the nightly news and by tipping public perception of global warming from something confusing, distant, and best ignored to something scary, immediate, and demanding attention. (It also brought home two often-forgotten lessons: that disasters exacerbate injustice and that race still matters.)

Sierra Club members already knew that if we don't stabilize the climate, all our previous gains--from protecting wildlife and wild places to cleaning up pollution--will be wiped out. The summit gave 5,200 Sierrans, the Club's largest gathering ever, an opportunity to affirm this shift in our priorities. Impelled by images of New Orleans and a powerful speech by Al Gore, Club activists made finding smart energy solutions the highest priority for the next five years.

The changes set in motion 18 months ago are already bearing fruit. Last November, voters delivered a stunning rebuke to President George W. Bush by electing a new leadership to Congress and many statehouses. Representative Roy Blunt (R-Mo.), who had promised that he would not do "anything meaningful" on global warming if he returned as majority whip, lost both his post and his majority. Public opinion polls now show that Americans believe global warming is the most important environmental problem we face, and energy issues were centerpieces in many campaigns. Ohio governor Ted Strickland (D) promised to invest a third of the state's bonds in alternative energy, while in California, the gubernatorial candidates competed for leadership on global warming. Windmills were the image of choice in the season's campaign ads.

Meanwhile the Club was developing a road map showing how the country can reduce its carbon dioxide emissions by more than three-fourths, generate hundreds of thousands of new jobs, improve public health, and lower its trade deficit. (For more information, go to sierraclub.org/energy/overview.) Already, the Club has helped persuade 11 states, representing about 30 percent of the U.S. auto market, to limit global-warming pollution from cars. Before the summit, some 160 cities had signed the U.S. Mayors Climate Protection Agreement to reduce greenhouse-gas emissions; after the Club launched its Cool Cities Campaign, the number nearly doubled. Fifteen states have adopted requirements that 10, 15, or even 20 percent of their electricity come from renewables in the next few years.

Faced with what may be humankind's greatest challenge, we've designed a three-part strategy: Prevent, prepare, and repair. To prevent the worst of climate change, we need to follow the first rule of holes: When in one, stop digging. Our government must set long-term policies that will shift investment toward clean energy and renewables. Business needs clear signals that decarbonizing our society will be profitable--and that those who lag will pay a price.

As Katrina taught us, we need to prepare our communities for weather shocks. Unstable rainfall will likely be among the first broadly felt impacts of climate change. Many U.S. cities and states are already overdrawing their water sources. In a world of climate chaos, we can't afford to pollute or waste a single drop; in the years to come, wise use of water will be as important as efficient use of energy.

Finally, we need to repair. We have to assist nature in cleaning up our mess, because only trees, soils, and the oceans can retire carbon from the atmosphere. Reforesting the tropics, for example, will expand the "carbon sinks" that keep excess CO2 out of the air. Protecting wildlands and establishing wildlife corridors will allow species to migrate as temperatures change and then return once the climate stabilizes. In recovering from our industrial folly, we may finally find ourselves becoming true stewards of the earth.

Carl Pope is the Sierra Club's executive director. E-mail carl.pope@sierraclub.org.

Photo by Lori Eanes; used with permission.