The debate over whether humans are to blame for Earth's rising temperatures isn't decided yet, but it is quickly being eclipsed by a new argument over who should manage global warming policy in the United States.

Some advocates are promoting a states-first approach that would enable states to pass environmental policies that proponents say could help chip away at emissions of greenhouse gases like carbon dioxide and methane. Those are just two elements widely blamed by scientists for rapidly rising temperatures that could endanger global health and regional economies.

Already, California, Arizona, New York and other states have taken it upon themselves to battle against those climate change contributors.

Editor's Note: This is the first in a two-part series on the conflict over greenhouse gas emissions in the United States. Tomorrow, look for best-selling author Edwin Black's one-man challenge to U.S. automakers to produce alternative fuel vehicles.

"There is a tremendous amount of activity [in the states]. It's underappreciated," said Tom Peterson, executive director of the Center for Climate Strategies, a consulting group that works on state-based plans to reduce greenhouse gases.

But others say a federal plan would be a more effective and holistic approach to fight global warming.

"I think this is an issue that the federal government should take the lead on because it is a national problem. You don't want the states to be doing different policies because it just creates a jurisdictional nightmare," said Brookings Institution climate policy scholar Warwick McKibbin.

Federal Necessity

The Environmental Protection Agency says it is committed to reducing the "greenhouse gas intensity" of the U.S. economy by 18 percent during the 10-year period from 2002 to 2012. That would entail reducing emissions by 500 million metric tons over the decade.

But critics say the effort amounts to a raindrop in the ocean considering that even if the EPA achieves its goal for the United States, by 2012 it will still be emitting 151 metric tons of greenhouse gases per million dollars of GDP. According to the Energy Information Administration, the United States emitted 7.14 billion metric tons of carbon dioxide-equivalent greenhouse gases in 2005.

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The 0.3 percent increase over the prior year, however, is an improvement, EIA says, as the average annual rate of carbon dioxide emissions has been 1.2 percent per year since 1990.

"It's lower than previous years, but it's still an increase" in the total greenhouse gases emitted, said Jonathan Cogan, a spokesman with EIA.

This fiscal year alone, the Bush administration is investing $6.5 billion in projects aimed at reducing carbon emissions, according to the Department of Energy. American Enterprise Institute congressional scholar Norman Ornstein said President Bush may also be feeling pressure to propose a new policy on global warming.

"Obviously, if that happened, you have an enormous difference on the whole policy dynamic," Ornstein said.

Rev. Paul de Vries, president of the New York Divinity School and one of 86 evangelicals who signed onto a February statement declaring global warming a problem, said that he welcomes the idea of states taking action, but in the end, the federal government must lead the way.

"I think [state action] helps to raise the awareness, and I think pushes up the ante for national officials to do the right thing," de Vries said. "It's really a global issue. There needs to be more coordination ... [and] definitely, it has to be national."

The federal government's role also needs to extend to the international arena, Ornstein said, adding that the United States must project leadership in places like China and India, where concerns are mounting over the rapidly growing economies and their greenhouse gas emissions.

McKibbin said he prefers market-based approaches to reducing carbon emissions, but they won't work without the force of the federal government. He added that a lack of clear federal policy contributes to the problem "because it slows economic growth."

He said the debate over oil consumption is a good example of how bad energy policy affects both the economy and the climate: Unclear policy has slowed the building of oil refining facilities, which has been a factor pushing up oil prices.

A wider array of energy sources — including renewable types like wind and solar power — and more efficient appliances and vehicles would help to ease energy prices shocks, McKibbin said.

Executives from some of the highest-grossing energy companies say they have begun advocating for alternative fuels including wind, solar and crop-based bio-fuels, but the market determines their direction.

"We're an energy company. We provide fuel," said Tim O'Leary of Shell Oil, adding that his company has spent $1 billion in the last five years on research into alternative fuels like solar, wind and hydrogen energy.

O'Leary said a partnership exists "between energy companies, car manufacturers and governments at the apex. In the middle is the public. We see a business opportunity here. ... We can afford to and have to invest" in other fuels.

Taking It to the States

Still, with 232 million vehicles on U.S. roads, the marketplace is demanding fossil fuels to continue its smooth operating.

That's part of the reason why the Alliance of Automobile Manufacturers is challenging California's decision to regulate carbon dioxide emissions from automobiles, saying it does not have the authority to put curbs on emissions that are not deemed noxious by the EPA.

"Under the Clean Air Act, carbon dioxide is not a pollutant," said Gloria Bergquist, vice president of public affairs for AAM, which represents eight of the nine automobile manufacturers in the United States.

"They're fighting for what they want. It's not so much a technology issue as a philosophical issue or political issue," said Jerry Martin, spokesman for the California Air Resources Board. "No company wants a government agency telling them what to do."

But some states, including California, along with environmental groups are challenging the federal government to take that next step. On Wednesday, the Supreme Court is hearing the case, Massachusetts et al v. the EPA, in which 12 states, three cities, the Sierra Club and other environmental advocacy organizations are demanding the EPA regulate, as a matter of public health, the amount of carbon dioxide that comes from vehicles.

These groups are also complaining that while Congress talks about environmental concerns, and the incoming Democratic majority next session says toughening the Clean Air Act will be a priority, the pace of action is slower than the icebergs chipping away from the Arctic circle.

"The states are only acting because the federal government isn't doing anything," said Daniel Becker, director of the Sierra Club's global warming program.

Fearing long-term effects of global warming — including predictions of stronger, more frequent hurricanes, drought and famine — states are quickly adopting policy, Peterson added.

According to an analysis by Peterson's group, 13 states have set timetables and targets for greenhouse gas reductions. Together, those state and others have taken 250 different actions to attempt to reduce greenhouse gases.

States also are looking at changing auto emissions standards and drafting interstate trade pacts that cap overall carbon emissions. Under the so-called "cap and trade" programs, electric utilities that don't use up all their allotted carbon emissions capacity could then sell it to others willing to purchase it.

"To steal a phrase that's been used before, these [state plans] are not looking for silver bullets. ... They're really looking for silver buckshot," Peterson said.

Ornstein said the federal government might need to step in to settle interstate battles, but in either case, it's unlikely major changes will happen overnight.

"There isn't much a state can do that doesn't cut across state lines," Ornstein said. "Doing anything that causes people pain ... becomes hard to do at any time. But it becomes harder to do when you don't have the walls crashing down on you."

Editor's Note: This is the first in a two-part series on the conflict over greenhouse gas emissions in the United States. Tomorrow, look for best-selling author Edwin Black's one-man challenge to U.S. automakers to produce alternative fuel vehicles.