WASHINGTON — Hillary Clinton and Barack Obama agree on the basics of global warming. Both believe scientists' warnings that it poses a catastrophic threat. Both demand urgent action, and both think there's still hope of escaping the worst consequences through technological advances, developing new energy sources and sharply reducing pollution.
In speeches and papers on their Web sites, the Democratic presidential candidates spell out what they'd do to reduce greenhouse gas emissions and make the country's energy supplies more secure. Both embrace the emission reduction goals that the world's scientists agree must be reached by mid-century to give the planet a chance to avoid irreversible climate dislocation.
Some economists say it's too tall an order. Obama and Clinton acknowledge that they're counting on some technologies that don't exist yet. But both say that their detailed plans, combined with a mighty mobilization akin to the nation's entry into World War II, will get the country on track to lead the world in doing what must be done.
While key parts of their plans are similar, each candidate offers some new ideas.
"We are a land of moon shots and miracles of science and technology that have touched the lives of millions across the planet," Obama said his key energy speech. "And when that planet is challenged or when it is threatened, the eyes of the world have always turned to this nation as the 'last, best hope of Earth.' "
"This is the biggest challenge we have faced in a generation," Clinton said when she rolled out her energy plan in Iowa. "It is a challenge to our economy, to our security, to our health and to our planet. And it's time for America to meet it."
"I think both of them understand that climate change is a real problem, that it's going to take some serious action to address it," said Manik Roy, the director of congressional affairs at the nonpartisan Pew Center on Global Climate Change. At the same time, he said, "They recognize there are a lot of interests that have to be balanced when making law."
Clinton and Obama — and presumptive Republican presidential nominee John McCain — say that while the environmental goals are very important, they want to meet them "in a way that allowed the economy to keep on working," Roy said.
The next president will face a leadership test next year, when the world's countries, including China and India, try to set up a new international system for reducing greenhouse gas emissions.
Daniel Yergin, the chairman of Cambridge Energy Research Associates, a company that advises governments and energy companies, declined to comment on the Democrats' individual plans, but he said that the task before them is huge and complex.
The U.S. is tightly integrated into global markets. It imports 60 percent of its oil and is on track to import significantly more natural gas than it is now, Yergin said.
"The major issue is how we manage our energy security and how we ensure we have resilience, how we have diversification, the importance of our relations with our suppliers, while at the same time maintaining this increased commitment to energy research and development . . . . For the foreseeable future we're going to be a significant importer of energy," he said.
Obama's and Clinton's plans look beyond the near term and cover many parts of an emerging shift how energy is produced and used.
Terry Tamminen, an adviser on energy and environmental policy to California Republican Gov. Arnold Schwarzenegger, looked at what the presidential candidates have said they'd do and graded them: he gave Clinton and Obama B's, but McCain got an F because he hasn't put out a specific plan.
Tamminen said the Democrats might rely too much on ethanol, which is now made in the United States from corn and doesn't substantially reduce greenhouse gas emissions.
Neither candidate rules out nuclear energy, though both warn that problems of waste storage and security must be worked out. Obama says it's unlikely that the world can meet climate goals without nuclear power. Clinton opposes new subsidies for nuclear power but supports more research to improve safety.
Another uncertainty is how they'd handle pressure for new conventional coal plants, the source of half the nation's electricity and much of its greenhouse gas emissions. Both want to speed development of a system to capture carbon dioxide, the main greenhouse gas, and store it permanently underground.
But that system is years off. Cambridge Energy Research Associates reported that "even in the best case, carbon capture and storage is at least two decades away from meaningful deployment."
Clinton's plan calls for accelerating the development of the storage system and improving efficiency so that fewer new power plants are needed. She'd require all new coal plants to be capable of adding carbon capture and storage systems when they become commercially available.
Obama wants to structure market forces to push coal companies into putting more effort into developing the storage system by putting a price on carbon emissions. Until the storage system is available, Obama said, he'd consider a ban on new traditional coal power plants.
Both want Congress to pass a law establishing a cap and trade system that would regulate much of the nation's greenhouse gas emissions. Both want the federal government to sell permits for 100 percent of the nation's emissions. The limit would decrease every year. Companies that emit less pollution could sell unused permits to those that emit more.
Clinton said last year that the cap and trade program, plus higher fuel economy standards and other efficiency programs, would make it possible to reduce U.S. emissions by 80 percent below 1990 levels by 2050. Obama's position paper calls for the cap and trade system to reduce emissions by that amount.
The Senate will start debate on a cap and trade bill in June.
Both candidates say that it's important to start regulation quickly because the longer the country waits, the steeper and more difficult the emission cuts will be. Some of the revenue from the emission-permit auctions would be used to develop clean energy and help low-income people pay their energy bills.
Clinton supports a "Connie Mac" (Carbon Neutral Mortgage Association) to make it easier to get loans for energy efficiency in homes.
Obama wants a National Low Carbon Fuel Standard that would require fuel suppliers to reduce the carbon that their fuel emits by 10 percent by 2020.
Other highlights from the two Democratic candidates' plans:
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McClatchy story on McCain and global warming