The shale gas boom in the US has led to a big drop in its carbon emissions, as power generators switch from coal to cheap gas.
According to the International Energy Agency, US energy-related emissions of carbon dioxide, the main greenhouse gas, fell by 450m tonnes over the last five years – the largest drop among all countries surveyed.
Fatih Birol, IEA chief economist, attributed the fall to improvements in fuel efficiency for transport and a “major shift” from coal to gas in power supply.
“This is a success story based on a combination of policy and technology – policy driving greater efficiency and technology making shale gas production viable,” Mr Birol said.
Shale gas has transformed the US energy landscape, with surging production reducing prices to ten-year lows and raising hopes of an industrial revival.
But it is also the subject of a heated environmental debate, with critics alleging that the production process can pollute groundwater.
Gas is fast becoming the fuel of choice for US energy. In the last 12 months, coal-fired generation has slumped by 19 per cent while that using gas has increased by 38 per cent, according to the US Department of Energy. A gas-fired plant produces half the CO2 emissions of a coal-fired one.
Overall, however, the IEA said 31.6 gigatonnes of CO2 were released into the atmosphere last year, mainly through the burning of fossil fuels. This was one gigatonne more than in 2010 and much higher than the average annual increase of 0.6 gigatonnes between 2006 and 2010.
“The impact of this increase is going to be catastrophic,” said John Sauven, Greenpeace executive director . “We’ve really got to act now, with a real sense of urgency, which up till now has been completely lacking.”
China’s carbon dioxide output increased by more than 700m tonnes last year, a 9.3 per cent rise. India overtook Russia to become the world’s fourth largest CO2 producer, after China, the US and the European Union.
While China pumps out more CO2 than any other country, its per capita emissions are only two-thirds of advanced countries. Mr Birol said China was making “major efforts” on energy efficiency, which had improved by 15 per cent in the past five years. Without these, he said, global carbon emissions would have been 1.5 gigatonnes higher.