THE MOVIE AN INCONVENIENT TRUTH and other media (including, may we humbly suggest, this magazine) have helped convince millions of people that arresting global warming is our generation's greatest challenge. The problem is international, but the United States, as the most profligate greenhouse-gas emitter, has a responsibility to take the lead. So how do we start?

The Sierra Club has made finding smart solutions to global warming its highest priority. For the past year, our volunteer leaders and energy experts have been examining the nation's energy options. We've launched a Cool Cities Campaign to make changes happen immediately at the local level. And we have nearly completed an "energy road map" that spells out how individuals, businesses, and government at all levels can move toward a more secure, sustainable future. In preparing that road map, Club experts started by considering the impacts of three courses of action:

BUSINESS AS USUAL

"Global warming is probably the biggest threat that has ever faced humanity. That is what is most scary about it--and also what is most exciting. A problem of this scale presents an opportunity for grand solutions: more just and sustainable ways of life that will not only stabilize the climate but also reinvigorate community, restore environmental and human health, and give us a secure world far more hopeful and fulfilling than the one we live in today." --Jared Duval, national director of the Sierra Student Coalition (from Ignition, a spring 2007 Island Press book)

In this scenario, Americans make no serious commitment to reducing our carbon dioxide emissions. As our economy grows, we burn more--not less--oil, coal, and natural gas. The carbon dioxide in the atmosphere, which was about 280 parts per million before the Industrial Age, rises from its current 380 ppm to 475 ppm by 2050. Global temperatures increase accordingly.

"No one knows exactly what will happen if things are left unchecked," says Scientific American editor Gary Stix. "But no climatologist wants to test what will arise if carbon dioxide levels drift much higher than 500 ppm."

BEST CURRENT PRACITICES In the second scenario, the United States takes many small steps in the right direction. All states adopt the progressive policies of Vermont and California, which use charges on utility bills to fund the most cost-effective efficiency measures. Congress finally passes moderate global-warming and fuel-economy legislation. Instead of subsidizing fossil fuels at almost twice the rate of renewables, the federal government gives both equal support. With these policies in place, energy efficiency and renewables expand. But our economy grows as well, requiring the use of even more fossil fuel. The dangerous upward trend in carbon emissions continues, albeit more slowly, demonstrating the futility of insufficient action and the difficulty of getting where we need to go.

AMERICA LEADS In the third scenario, our country embraces not only today's best practices but also tomorrow's opportunities. We approach global warming as if our survival were at stake, constructing a "war effort" like the Army's Manhattan Project. The entire country embraces policies that go further than any state's have yet. For a transition period, we continue to drill existing oil leases and burn coal. At the same time, we use energy more efficiently than ever--significantly reducing our need for fossil fuel. We steer clear of new nuclear power plants and invest in safer alternatives: wind, solar, oceans, and biomass. We proactively slant subsidies to favor renewables. We get prices right: The high cost of pollution is reflected in how much consumers pay for their energy. Suddenly getting your power from a coal-fired plant costs a lot more than using wind or even solar power. As renewable energy becomes cheaper than fossil fuels, change happens fast. We dramatically reduce our carbon dioxide emissions, bringing them down to the levels scientists say are necessary to prevent the worst effects of global warming: 80 percent below 1990 levels by 2050.

Only this scenario offers future generations a road map to a brighter future. It requires major changes, but many of them provide multiple social, economic, and environmental benefits. Americans have gotten ourselves out of tough jams and overcome big obstacles before. We cured polio, put a man on the moon, and ended segregation. If we set our minds to it, we could also meet the enormous challenge of global warming. We already have the know-how. Unleashed, American ingenuity could build cars that get 100 miles per gallon. It could produce energy from wind, the sun, and green plants to power millions of homes. It could make machines and buildings that run on a fraction of the energy they use now. As stewards of the planet, caretakers of creation, and responsible parents, how can we do otherwise?

THREE ENERGY FUTURES

Click to see larger version of chart.

The Sierra Club is looking at three ways the nation's future could unfold between now and 2050. In each case, our experts are calculating how certain national policies would change U.S. consumption of oil, coal, and natural gas--the fossil fuels that destabilize the climate by producing carbon dioxide and other greenhouse gases. In the "Business as Usual" scenario, these emissions from fossil fuels rise quickly, as do global temperatures, triggering climate chaos. In "Best Current Practices," fossil-fuel use inexorably grows, but a little more slowly. Only "America Leads" offers future generations a chance to thrive, by dramatically shrinking our dependence on fossil fuels and greatly increasing our energy efficiency and use of renewable energy sources.

ON THE WEB
For more on Sierra Club solutions to the global-warming problem, go to sierraclub.org/energy. To help in your community, go to our Cool Cities Campaign site at coolcities.us. Information on the Sierra Student Coalition's Campus Climate Challenge is featured at ssc.org.

Photo courtesy of City of Chicago/Mark Farina
Chart: from the Sierra Club's "Safe Energy Solutions" slide show, sierraclub.org/energy