This is the VOA Special English Economics Report.

One of the top issues this week at the World Economic Forum in Davos, Switzerland, was climate change. But the business and political leaders gathered for the yearly event in the Swiss Alps were not the only ones talking about the subject.

President Bush, in his State of the Union message Tuesday, proposed rules to increase production of renewable fuels, like ethanol from corn. He also said new technologies are needed to deal with what he called "the serious challenge of climate change."

California recently passed rules to require industries to release less carbon dioxide and other gases blamed for trapping heat. Some companies believe it is just a question of time before the federal government could do the same. So they are positioning themselves to have a voice in the policy-making.

On Monday, leaders of ten big companies proposed federal rules to limit the release of greenhouse gases. The companies are members of the United States Climate Action Partnership.

One possibility for the country is a trading system like the European Union has. Companies would have permits to release a set amount of greenhouse gases. Businesses that stay within their limits could trade their surplus to bigger polluters.

Since nineteen ninety-five, the United States has had a trading system for sulfur emissions that cause acid rain.

But some companies think other ideas, like new taxes on polluters, are a better way to cut greenhouse gases.

Any new rules would hit some industries harder than others. For example, forty percent of the carbon dioxide from American industry comes from power producers, especially those that burn coal. The United States is the world's biggest producer of carbon dioxide, followed by China.

On February second, in Paris, a scientific group established by the United Nations plans to release a major report on climate change. The report, six years after the last one, is expected to take the strongest position yet about the influence of human activity.

The group is said to be at least ninety percent sure that human activity is the main cause of global warming in the last half-century. The Intergovernmental Panel on Climate Change puts most of the blame on the burning of fossil fuels. And the report is expected to say that scientists around the world believe temperatures will continue to rise.

And that's the VOA Special English Economics Report. Transcripts and MP3 files are at WWW.51VOA.COM. I'm Mario Ritter.