New paper finds only ~3.75% of atmospheric CO2 is man-made from burning of fossil fuels

The Hockey Schtick:

A paper published today in Atmospheric Chemistry and Physics finds that only about 3.75% [15 ppm] of the CO2 in the lower atmosphere is man-made from the burning of fossil fuels, and thus, the vast remainder of the 400 ppm atmospheric CO2 is from land-use changes and natural sources such as ocean outgassing and plant respiration.

According to the authors, 

We find that the average gradients of fossil fuel CO2 in the lower 1200 meters of the atmosphere are close to 15 ppm at a 12 km × 12 km horizontal resolution.

The findings are in stark contrast to alarmist claims that essentially all of the alleged 130 ppm increase in CO2 since pre-industrial times is of man-made origin from the burning of fossil fuels, finding instead that only 15 ppm or ~11.5% of the increase is of fossil fuel origin. The findings cast additional doubt upon theIPCC carbon-cycle Bern Model, previously falsified by the atomic bomb tests. 

Furthermore, if use of fossil-fuels has contributed such a small part of total atmospheric CO2 levels, restricting use of fossil fuels will have little effect upon CO2 levels. 

Full paper open access:

Atmos. Chem. Phys., 14, 7273-7290, 2014 www.atmos-chem-phys.net/14/7273/2014/ doi:10.5194/acp-14-7273-2014 Simulating the integrated summertime Δ14CO2 signature from anthropogenic emissions over Western Europe

D. Bozhinova¹, M. K. van der Molen¹, I. R. van der Velde¹, M. C. Krol^1,2, S. van der Laan³, H. A. J. Meijer³, and W. Peters^1
1Meteorology and Air Quality Group, Wageningen University, the Netherlands
²Institute for Marine and Atmospheric Research Utrecht, Utrecht, the Netherlands
³Centre for Isotope Research, University of Groningen, Groningen, the Netherlands

Abstract. Radiocarbon dioxide (¹⁴CO₂, reported in Δ¹⁴CO₂) can be used to determine the fossil fuel CO₂ addition to the atmosphere, since fossil fuel CO₂ no longer contains any ¹⁴C. After the release of CO₂ at the source, atmospheric transport causes dilution of strong local signals into the background and detectable gradients of Δ¹⁴CO₂ only remain in areas with high fossil fuel emissions. This fossil fuel signal can moreover be partially masked by the enriching effect that anthropogenic emissions of ¹⁴CO₂ from the nuclear industry have on the atmospheric Δ¹⁴CO₂ signature. In this paper, we investigate the regional gradients in ¹⁴CO₂ over the European continent and quantify the effect of the emissions from nuclear industry. We simulate the emissions and transport of fossil fuel CO₂and nuclear ¹⁴CO₂ for Western Europe using the Weather Research and Forecast model (WRF-Chem) for a period covering 6 summer months in 2008. We evaluate the expected CO₂ gradients and the resulting Δ¹⁴CO₂ in simulated integrated air samples over this period, as well as in simulated plant samples.

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