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More than hot air

The United States has finally acknowledged that global warming is a threat. It must now act on that.

Last week, the US Environmental Protection Agency (EPA) opened up yet another front in the climate-policy debate by issuing a document that proposes to acknowledge that greenhouse gases pose a threat to human welfare. To climate scientists, that statement, which is subject to a 60-day comment period, may sound like an utterly bland assertion of the obvious. But sadly — because it should have happened long ago — the announcement is exactly what so many supporters have hailed it to be: a landmark in US environmental history. It is the EPA's first formal claim that it has the power to regulate greenhouse-gas emissions without any further authorization from Congress.

What is not yet clear is how this action is going to play out. In one scenario, for example, the EPA would indeed go it alone. The US Supreme Court endorsed the agency's authority to do so in 2007, when it ruled that greenhouse gases from vehicles could be regulated under the Clean Air Act if the EPA determined that they posed a threat to humans — as the agency now proposes to do. It could start by setting a limit on greenhouse-gas emissions for all transportation fuels, or by setting carbon-based standards for energy-intensive industries.

As worthwhile as such efforts would be, however, nobody really wants the EPA to go solo on climate. Successfully reducing US carbon emissions by any amount, let alone meeting the administration's goal of cutting them to 80% of 1990 levels by mid-century, will require a framework of law, regulations and incentives that encompass all of US society. And for action of that magnitude, the EPA and every other relevant agency should have the imprimatur of society's representatives in Congress.

In an alternative scenario — the one that advocates of climate legislation are hoping for — the looming threat of the EPA's regulatory authority would nudge all sides to the table for a grand congressional bargain on greenhouse-gas regulations. The presumption is that business leaders, Republicans, coal-state Democrats and others wary of climate regulation will figure that they have a better chance of protecting their interests in Congress than in the deliberations of EPA technocrats. Supporters, meanwhile, will figure that a congressional stamp of approval will help to avoid long legal challenges about every detail of the regulations, as well as the prospect of a loss in court. (Just such an outcome occurred last year when a fight over regulatory details led a federal appeals court to toss out an emissions-trading programme designed to lessen the amount of smog that drifts east from power plants in the Midwest.)

In the meantime, President Barack Obama has rightly chosen to focus his climate-change efforts on Capitol Hill, where several bills have already been introduced to regulate greenhouse gases by a cap-and-trade system. Unfortunately, his administration hasn't exactly been crystal clear about what it expects from Congress and when. This is perhaps understandable, given the energy that Obama has been forced to dedicate to the ongoing economic crisis, but the administration will eventually have to wade into the debate, get involved in the negotiations and demonstrate real leadership in this area.

The good news is that Obama seems to understand the complexities of the problem. His science adviser John Holdren recently told Nature that Obama has shown “a willingness and an ability to keep issues together when they need to be together”. Irrespective of how popular his policies might be, there is little doubt that Obama has shown a bold — some would say brash — inclination to break with the stove-piped policymaking of the past. Energy and climate, for example, had for some time been handled separately but are now part of a single discussion that includes competitiveness and economic recovery. Still, comprehensive reform will always be more difficult than a piecemeal approach. In his short time in office, Obama has showed his willingness to push for reform on numerous fronts. Now he needs to prove he can follow through.

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More than hot air. Nature 458, 945–946 (2009).

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