US President Barack Obama reinforced environment promises in his second inaugural address. Credit: ZUMA/Rex Features

Throughout his re-election campaign, US President Barack Obama rarely said the words ‘climate change’. But in his second inaugural address, on 21 January, Obama renewed a commitment to address global warming, citing both moral and economic imperatives. To fail, he said, “would betray our children and future generations”.

The 2010 demise of a climate bill that would have enacted a cap-and-trade system to limit greenhouse-gas emissions remains one of the key failures of Obama’s first term. With a divided Congress still standing in the way of legislation, the administration is likely to rely on its own power to impose new regulations, once Obama has replaced the retiring heads of three agencies key to the climate agenda (see ‘Climate team change’).

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As proof of what is possible, Obama can point to a welcome, if unexpected, reduction in US greenhouse-gas emissions during his first term. The decline is in part a result of the economic slowdown and a shift in electricity production from coal to natural gas, which has become cheap and plentiful in recent years. But policies have helped. These include federal greenhouse-gas standards for vehicles, and the introduction by more than half of the states of significant energy and climate initiatives that could deliver further reductions — perhaps even the 17% cut by 2020 that Obama promised at the United Nations climate summit in Copenhagen in 2009.

Many see the reductions as an opportunity. They “should give Americans confidence that climate policies can be effective”, says Paul Bledsoe, an environmental consultant in Washington DC and a White House climate-change official under former president Bill Clinton.

As a next step, Obama’s administration is expected to impose two greenhouse-gas regulations targeted at power plants, which are responsible for roughly 40% of US emissions. The first, proposed last year by the Environmental Protection Agency but not yet finalized, would limit emissions from new plants, effectively banning the construction of coal-fired plants that are not equipped to capture and sequester carbon dioxide.

A second rule, not yet released, could set emissions limits for existing plants, encouraging the shift towards natural gas. Other rules could target the oil and gas industry by limiting emissions from refineries and drilling sites.

But these piecemeal regulatory efforts will not be sufficient to reduce emissions by 83% by mid-century — a target promised by Obama at the Copenhagen talks. One question is whether the president can build support for a broad programme of energy research and development that could drive down the cost of large-scale, low-carbon energy, and ultimately make a carbon tax or a cap-and-trade agreement politically palatable.

The President’s Council of Advisors on Science and Technology has recommended increasing spending on energy research and development from around US$4 billion per year to $16 billion, and some organizations have advocated even more. Armond Cohen, executive director of the Clean Air Task Force in Boston, Massachusetts, argues that Obama could attract conservative support for a strategic research programme focused on large-scale energy technologies such as carbon capture and storage methods and advanced nuclear reactors. Such a programme might look like the energy department’s Advanced Research Projects Agency-Energy, itself inspired by a similar defence-department programme, says Cohen. Once technologies are developed, government agencies could use their buying power to expand production and reduce prices.

“We don’t want to see Obama walk in and just play small ball again,” says Cohen. “Obama really needs to take this innovation problem on head on.”