Efforts in the United States to introduce federal legislation on climate change have been given greater urgency by news that the shale gas 'miracle', which delivered both lower electricity prices and reduced emissions of carbon dioxide, has stalled.
New figures from the Energy Information Administration show that energy-related carbon dioxide emissions in 2013 were 2.1 per cent higher than the previous year, due mainly to an increase in the amount of coal being burned in power stations.
The Administration forecasts that emissions will rise again this year, as the increasing price of natural gas leads to higher coal consumption for electricity generation, but will fall slightly in 2015 when new regulations limiting emissions of mercury, arsenic and lead force the closure of many older power stations.
The figures for 2013 mark the end of a downward trend in annual energy-related emissions, with a fall of 12.4 per cent between the peak in 2007 and 2012.
According to the latest figures published by the Environmental Protection Agency, total annual emissions of greenhouse gases by the United States were 6.9 per cent lower in 2011 than in 2005, but still 8.4 per cent higher than their 1990 level, which is the baseline used by the United Nations Framework Convention on Climate Change.
President Obama's administration has set a goal of reducing annual emissions by 17 per cent by 2020 compared with 2005.
His attempts to introduce federal legislation to tackle climate change since he took office have been thwarted by a lack of support from Congress.
Although the Senate passed a Bill in 2009 to introduce a cap and trade system, Republicans have opposed the measure since taking control of the House of Representatives in 2010.
The President presented a new Climate Action Plan last June, outlining efforts to further reduce emissions without the need for new legislation. He instructed the Environmental Protection Agency to introduce new limits on carbon dioxide emissions that are eventually expected to prevent the burning of coal in power stations that are not fitted with carbon capture and storage technology.
Although some States, particularly California, have enacted their own legislation to tackle climate change, the large reductions in emissions that are needed if the United States is to play its part in international efforts to avoid global warming of more than 2 centigrade degrees appear unlikely without federal laws.
Last week, two Democrat Senators, Barbara Boxer and Sheldon Whitehouse, announced that they had set up a task force to push for more action on climate change.
Senator Boxer wrote a newspaper article earlier this month which made the case for Congress passing a Bill to introduce carbon pricing.
The Senate Environment and Public Works Committee that she chairs is also due to hold a hearing about President Obama's Climate Action Plan on 16 January.
Campaigners are hoping to keep up the pressure on Congress, with a new initiative spearheaded by Michael Bloomberg, the former mayor of New York, Hank Paulson, President Bush's Treasury Secretary, and Tom Steyer, a major funder of Democrats who favour climate legislation.
'Risky Business' will highlight the potential economic threats that the United States faces from unmanaged climate change, with a hard-hitting report due out later this year.
It will follow the publication of the final report of the National Climate Assessment. The draft version last year warned that "climate change is already affecting the American people".
However, the Republican Party still opposes any attempts to limit greenhouse gas emissions, and some of its members, particularly those supported by the Tea Party, deny that human activities are causing climate change.
Without Republican support for a new Bill to tackle climate change, the United States will find it difficult to play a leading role in the negotiation of a new international agreement, which is due to be signed at the United Nations summit in Paris in December 2015.
Bob Ward is policy and communications director at the Grantham Research Institute on Climate Change and the Environment and the Centre for Climate Change Economics and Policy at London School of Economics and Political Science.