While scientists worry about a warming world, some companies say that with the right moves, the United States could cut its output of greenhouse gases 60 percent to 80 percent by the middle of the century.
They say there are steps that can be taken now, and they need not be painful. They may even prove profitable.
"We believe that technology is one of the keys to driving a reduction in greenhouse gas emissions and productivity at the same time," said Jeffrey Immelt, the CEO of General Electric, at a meeting Jan. 22.
GE is one of 10 large companies that joined with environmental groups to make "a call for swift action on global climate change."
Among other steps, they broke with other companies to propose that the government pass aggressive plans to curb production of carbon dioxide and other gases, such as methane, that scientists say trap heat in the atmosphere and warm the planet.
They added proposals that they said would make such curbs less expensive to the American economy. Among other things, they suggested a cap-and-trade system, so that if one business is struggling to meet the greenhouse goals, it can team with other companies that are ahead of schedule.
An electric company that burns a lot of coal, for instance, could buy emission credits from another that relies on so-called renewable energy. All that matters in the end, under this plan, would be that the total output of greenhouse gases goes down.
All sorts of other ideas are out there. Engineers are looking at ways to capture the carbon dioxide that comes out of a smokestack or a car's engine. Executives said companies that find a way could become very rich.
"We firmly believe that climate change can be addressed in ways that create more economic opportunity than economic risk," said Peter Darby, the head of Pacific Gas & Electric, the largest utility in Northern California.
In the meantime, many firms are turning to energy efficiency. The new headquarters of the Hearst Corp. in New York, for instance, gets much of its indoor lighting from sunlight. Construction of so-called "green" buildings is going up 20 percent a year.
"If you can save money and do something good for the planet, then why wouldn't you want to do it?" says Paul Westbrook of Texas Instruments, one firm that has invested in energy efficiency.
But some advocates -- some from corporations, many from environmental groups -- say not much will happen without a push from government.
"Congress needs to pass serious global warming legislation as quickly as possible," said Fred Krupp, the head of Environmental Defense. "Let me repeat those last four words: as quickly as possible."
The Bush administration is against that -- especially if other countries, such as China and India, do not do the same.
President Bush unveiled a plan in last month's State of the Union address to reduce America's gasoline consumption by 20 percent in the next 10 years. One of his principal proposals: to ramp up the use of cellulosic ethanol, a form of alcohol, made from virtually any kind of plant that could be mixed with gasoline.
The administration praised the report released today in Paris by the Intergovernmental Panel on Climate Change.
"We're embracing it. We agree with it," said Energy Secretary Sam Bodman at a Washington news conference. "Human activity is contributing to changes in Earth's climate, and that issue is no longer up for debate."
But he stood by the White House's previous opposition to mandatory greenhouse gas cuts, warning that if the U.S. makes changes and other countries do not, business will go overseas.
"We are a small contributor to the overall," he said. "It's got to be a global solution."