ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-10-2655-2010 The global SF<sub>6</sub> source inferred from long-term high precision atmospheric measurements and its comparison with emission inventories Levin I. 1 Naegler T. 1 Heinz R. 1 Osusko D. 1 Cuevas E. 2 Engel A. 3 Ilmberger J. 1 Langenfelds R. L. 4 Neininger B. 5 Rohden C. v. 1 Steele L. P. 4 Weller R. 6 Worthy D. E. 7 Zimov S. A. 8 Institut für Umweltphysik, Universität Heidelberg, INF 229, 69120 Heidelberg, Germany Centro de Investigación Atmosférica de Izaña, Instituto Nacional de Meteorología (INM), C/La Marina, 20, Planta 6, 38071 Santa Cruz de Tenerife, Spain Institut für Atmosphäre und Umwelt, J. W. Goethe Universität Frankfurt, Altenhöferallee 1, 60438 Frankfurt/Main, Germany Centre for Australian Weather and Climate Research / CSIRO Marine and Atmospheric Research (CMAR), Private Bag No. 1, Aspendale, Victoria 3195, Australia MetAir AG, Flugplatz, 8915 Hausen am Albis, Switzerland Alfred Wegener Institut für Polar- und Meeresforschung, Am Handelshafen 12, 27570 Bremerhaven, Germany Environment Canada, Climate Research Division/CCMR, 4905 Dufferin St., Toronto, ON M3H 5T4, Canada North East Section of the Russian Academy of Sciences, P.O. Box 18, Cherskii, Republic of Sakha (Yakutia), Russia 18 03 2010 10 6 2655 2662 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/10/2655/2010/acp-10-2655-2010.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/10/2655/2010/acp-10-2655-2010.pdf

Emissions of sulphur hexafluoride (SF<sub>6</sub>), one of the strongest greenhouse gases on a per molecule basis, are targeted to be collectively reduced under the Kyoto Protocol. Because of its long atmospheric lifetime (estimated as 800 to 3200 years), the accumulation of SF<sub>6</sub> in the atmosphere is a direct measure of its global emissions. Examination of our extended data set of globally distributed high-precision SF<sub>6</sub> observations shows an increase in SF<sub>6</sub> abundance from near zero in the 1970s to a global mean of 6.7 ppt by the end of 2008. In-depth evaluation of our long-term data records shows that the global source of SF<sub>6</sub> decreased after 1995, most likely due to SF<sub>6</sub> emission reductions in industrialised countries, but increased again after 1998. By subtracting those emissions reported by Annex I countries to the United Nations Framework Convention of Climatic Change (UNFCCC) from our observation-inferred SF<sub>6</sub> source leaves a surprisingly large gap of more than 70–80% of non-reported SF<sub>6</sub> emissions in the last decade. This suggests a strong under-estimation of emissions in Annex I countries and underlines the urgent need for independent atmospheric verification of greenhouse gases emissions accounting.

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