WASHINGTON -- The Copenhagen global warming summit is less than a month away, with major agreement far from certain. The U.S. Senate is so riven that President Barack Obama's top climate aide says legislation will be pushed off until 2010 at the earliest. Still, Washington can meet the challenge of a world demanding that it finally take the lead on global warming. Here's how:

Using his executive authority, Mr. Obama can instruct power plants to burn cleaner fuels, order new efficiency standards to reduce the energy used by consumer and commercial appliances, and help the world's least-developed nations use solar power -- rather than heavily polluting wood fires -- for cooking.

If he does these things, he would send a strong signal that Washington is leading the world away from an inexorably and dangerously warming climate, while pressuring other major polluting nations to get on board. He also would be dispatching his delegates to the Copenhagen summit with powerful tools: meaningful reductions in greenhouse-gas emissions.

Motor vehicles and power plants account for two-thirds of the nation's emissions of carbon dioxide, the main global-warming gas.

Tackling pollution from our ubiquitous motor vehicles, Mr. Obama has ordered that by 2016, new cars and light trucks sold in the United States must cut their tailpipe emissions by 30 percent. It is the biggest single step in U.S. history to reduce the nation's global-warming pollution and a significant down payment that demonstrates his willingness to act.

Complementing that decision, he could order the Environmental Protection Agency to issue new rules under the Clean Air Act to cut heat-trapping emissions from major power plants, oil refineries and other big industrial sources. These rules could require coal-fired power plants to switch to cleaner natural gas.

Converting the 100 dirtiest would cut pollution from coal-fired power plants by 15 percent, according to David Bookbinder, the Sierra Club's chief climate counsel. "It's incredibly efficient as a step to save carbon-dioxide emissions," Mr. Bookbinder says.

To be sure, polluters would seek to slow the change-over by challenging the rule in court. The administration would need to act vigorously, seeking quick court action and pressuring polluters to innovate, not litigate.

While Mr. Obama can clean up power plants, he also can act to reduce the amount of energy they need to produce. He can cut demand for electricity by speeding up new standards for household and commercial appliances -- from window air conditioners and microwave ovens to walk-in freezers and commercial boilers. Less electricity means less coal means fewer emissions.

As Energy Secretary Steven Chu put it: "Energy efficiency can be improved very quickly. ... Appliance standards, ka-BOOM, can be had right away."

By 2020, current standards will reduce carbon-dioxide emissions by 6.5 percent. With the stroke of a pen, Mr. Obama can further toughen standards and accelerate their start date for an additional reduction of 1.3 percent over the same period, according to a July report by the Appliance Standards Awareness Project.

The United Nations estimates that 2.5 billion people rely on wood, dung and other dirty fuels for cooking. The short-lived carbon soot from their fires produce a significant amount of global warming. Reducing it would quickly give us more time to deal with the long-range carbon-dioxide problem.

Mr. Obama can expand projects in the developing world that have been funded by the U.S. Agency for International Development and the EPA and send solar cookers to impoverished people from Haiti to Kenya to Nepal.

It is not unusual, says Paul Munsen, president of Sun Ovens International Inc., which sells solar cookers, for a family to spend half its income on charcoal, or many of its waking hours scavenging for wood. Trading some of the fires for solar stoves would save money, time, forests and a significant amount of greenhouse-gas emissions.

Simple cardboard-and-aluminum stoves are manufactured for as little as $8 each, according to Solar Cookers International, a nonprofit organization that distributes solar stoves to impoverished communities abroad.

Historically the world's largest climate polluter, the United States, now second only to China, has an obligation to lead and the resources and technology to act.

The top White House climate adviser, Carol M. Browner, says it "is not likely" that Congress will pass a major climate bill this year. But legislation is not the only route to progress.

With its clean-car order, the Obama administration has taken a first powerful step to reduce America's carbon footprint. Without waiting for Congress, the administration can expand its efforts to include cleaner power plants, more-efficient appliances and low-tech solar cookers.

Taking the initiative, Mr. Obama would challenge the major countries in the developed and developing world to step up the fight against global warming. Most important, he would improve the odds for the Copenhagen summit to produce a sound climate treaty.

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