When President Barack Obama was in Copenhagen on Oct. 2, he was trying to attract an Olympic Games for Chicago.

Next time, he should aim higher: He should try to help save the planet from global warming.

In December, representatives from 190 countries will meet in Copenhagen to start hammering out a new climate change treaty.

It's crucial that those negotiations not meet the same fate as Chicago's failed Olympic bid.

The evidence of man-made global warming is simply overwhelming, as virtually every national climatology and scientific society — including the U.S. National Academies of Science and the U.N. Intergovernmental Panel on Climate Change — have acknowledged. The planet is warming. The pace of change is occurring faster than even the worst-case scenarios had predicted.

To avoid the most serious consequences, developed and developing nations must act together to significantly reduce emissions of greenhouse gases.

The only reasonable hope of achieving that is a new treaty to replace the Kyoto Climate Accord, which will expire in 2012.

Mr. Obama clearly would have something to brag about at the meeting. He can point to significant efforts to curtail carbon-dioxide emissions, including two that have occurred in the last week.

Among those efforts are new regulations to control greenhouse gas emissions that were proposed last week by the U.S. Environmental Protection Agency.

And a new bill introduced in the Senate would create market-based controls on carbon-dioxide emissions. The House already has passed a similar measure.

The new EPA regulations would apply to big power plants, oil refiners and manufacturing facilities that each release more than 25,000 tons of carbon dioxide per year. That's the amount that would be generated by burning 131 rail cars of coal.

Those facilities together account for about 70 percent of the nation's greenhouse gas emissions. It is both logical and productive to start by regulating them.

Earlier this year, the Obama administration announced agreements with automakers that would reduce greenhouse gas emissions from new cars and trucks. That rule will take effect next year.

The Senate bill and proposed new EPA rules are not likely to win quick approval.

Industry groups, including the U.S. Chamber of Commerce, which is spearheading the opposition, already have begun running ads against the cap-and-trade bill.

But the chamber has suffered some high-profile defections as a result of its obstructionist efforts. Three large utility companies, the computer maker Apple and shoe giant Nike have resigned from the chamber in recent weeks.

Even without final approval of a cap-and-trade bill, Mr. Obama's efforts to curtail U.S. greenhouse gas emissions will give him vastly more international influence when negotiators begin shaping details of the new agreement.

He probably will need it.

World leaders paid lip service to the need for reform during a U.N. summit on climate change in New York last month. But that rhetoric wasn't matched by performance.

Channeling former President George W. Bush, China's Hu Jintao pledged to reduce the "carbon intensity" of his country's economy. Together, China and the United States account for about 40 percent of the world's greenhouse gas emissions.

Despite the obstacles, Mr. Obama should do what it takes — including making a personal appeal — to move reluctant world leaders to reach an agreement.

Compared to the catastrophic environmental changes that scientists say climate change can unleash, another trip to Copenhagen is a small price to pay.