Tornado Alley (PROG)

[F6]

and here's the GRL abstract and link:

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Is the airborne fraction of anthropogenic CO2 emissions increasing?

Wolfgang Knorr
Department of Earth Sciences, University of Bristol, Bristol, UK

Several recent studies have highlighted the possibility that the oceans and terrestrial ecosystems have started loosing part of their ability to sequester a large proportion of the anthropogenic CO2 emissions. This is an important claim, because so far only about 40% of those emissions have stayed in the atmosphere, which has prevented additional climate change. This study re-examines the available atmospheric CO2 and emissions data including their uncertainties. It is shown that with those uncertainties, the trend in the airborne fraction since 1850 has been 0.7 ± 1.4% per decade, i.e. close to and not significantly different from zero. The analysis further shows that the statistical model of a constant airborne fraction agrees best with the available data if emissions from land use change are scaled down to 82% or less of their original estimates. Despite the predictions of coupled climate-carbon cycle models, no trend in the airborne fraction can be found.

Received 18 August 2009; accepted 23 September 2009; published 7 November 2009.

Citation: Knorr, W. (2009), Is the airborne fraction of anthropogenic CO2 emissions increasing?, Geophys. Res. Lett., 36, L21710, doi:10.1029/2009GL040613.

http://www.agu.org/pubs/crossref/2009/2009GL040613.shtml

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note that this study is not arguing that CO2 concentrations in the atmosphere aren't rising, or that anthropogenic CO2 emissions aren't the source of rising CO2 concentrations in the atmosphere -- just that it can be said, with some massaging of the data, that the portion, or 'fraction', of anthropogenic CO2 emissions remaining in the atmosphere, i.e. not being absorbed into the oceans and land masses, has not risen as atmospheric CO2 concentrations have risen