Atmospheric verification of anthropogenic CO2 emission trends

Nature Climate Change(2013)

Francey R J, Trudinger C M, van der Schoot M, Law R M, Krummel P B, Langenfelds R L, Steele L P, Allison C E, Stavert A R, Andres R J and Rödenbeck C

DOI: 10.1038/nclimate1817

Vol 3, pp 520–524

Abstract

International efforts to limit global warming and ocean acidification aim to slow the growth of atmospheric CO2, guided primarily by national and industry estimates of production and consumption of fossil fuels. Atmospheric verification of emissions is vital but present global inversion methods are inadequate for this purpose. We demonstrate a clear response in atmospheric CO2 coinciding with a sharp 2010 increase in Asian emissions but show persisting slowing mean CO2 growth from 2002/03. Growth and inter-hemispheric concentration difference during the onset and recovery of the Global Financial Crisis support a previous speculation that the reported 2000–2008 emissions surge is an artefact, most simply explained by a cumulative underestimation (~ 9 Pg C) of 1994–2007 emissions; in this case, post-2000 emissions would track mid-range of Intergovernmental Panel on Climate Change emission scenarios. An alternative explanation requires changes in the northern terrestrial land sink that offset anthropogenic emission changes. We suggest atmospheric methods to help resolve this ambiguity.