title: Drivers of the US CO2 emissions 1997-2013.
abstract: Fossil fuel CO2 emissions in the United States decreased by ∼11% between 2007 and 2013, from 6,023 to 5,377 Mt. This decline has been widely attributed to a shift from the use of coal to natural gas in US electricity production. However, the factors driving the decline have not been quantitatively evaluated; the role of natural gas in the decline therefore remains speculative. Here we analyse the factors affecting US emissions from 1997 to 2013. Before 2007, rising emissions were primarily driven by economic growth. After 2007, decreasing emissions were largely a result of economic recession with changes in fuel mix (for example, substitution of natural gas for coal) playing a comparatively minor role. Energy-climate policies may, therefore, be necessary to lock-in the recent emissions reductions and drive further decarbonization of the energy system as the US economy recovers and grows.
authors.affiliation: Department of Geographical Sciences, University of Maryland, College Park, Maryland 20742, USA.
authors.forename: Kuishuang
authors.initials: K
authors.lastname: Feng
authors.affiliation: Department of Earth System Science, University of California, Irvine, Irvine, California 92697, USA.|Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Davis
authors.affiliation: Department of Geographical Sciences, University of Maryland, College Park, Maryland 20742, USA.|Department of Financial and Management Studies, SOAS, University of London, London WC1H 0XG, UK.|International Institute for Applied Systems Analysis (IIASA), A-2361 Laxenburg, Austria.
authors.forename: Laixiang
authors.initials: L
authors.lastname: Sun
authors.affiliation: Department of Geographical Sciences, University of Maryland, College Park, Maryland 20742, USA.
authors.forename: Klaus
authors.initials: K
authors.lastname: Hubacek