Atmospheric histories and emissions of chlorofluorocarbons CFC-13 (CClF3), ΣCFC-114 (C2Cl2F4), and CFC-115 (C2ClF5)
Martin K. Vollmer1,Dickon Young2,Cathy M. Trudinger3,Jens Mühle4,Stephan Henne1,Matthew Rigby2,Sunyoung Park5,Shanlan Li5,Myriam Guillevic6,Blagoj Mitrevski3,Christina M. Harth4,Benjamin R. Miller7,8,Stefan Reimann1,Bo Yao9,L. Paul Steele3,Simon A. Wyss1,Chris R. Lunder10,Jgor Arduini11,12,Archie McCulloch2,Songhao Wu5,Tae Siek Rhee13,Ray H. J. Wang14,Peter K. Salameh4,Ove Hermansen10,Matthias Hill1,Ray L. Langenfelds3,Diane Ivy15,Simon O'Doherty2,Paul B. Krummel3,Michela Maione11,12,David M. Etheridge3,Lingxi Zhou16,Paul J. Fraser3,Ronald G. Prinn15,Ray F. Weiss4,and Peter G. Simmonds2Martin K. Vollmer et al.Martin K. Vollmer1,Dickon Young2,Cathy M. Trudinger3,Jens Mühle4,Stephan Henne1,Matthew Rigby2,Sunyoung Park5,Shanlan Li5,Myriam Guillevic6,Blagoj Mitrevski3,Christina M. Harth4,Benjamin R. Miller7,8,Stefan Reimann1,Bo Yao9,L. Paul Steele3,Simon A. Wyss1,Chris R. Lunder10,Jgor Arduini11,12,Archie McCulloch2,Songhao Wu5,Tae Siek Rhee13,Ray H. J. Wang14,Peter K. Salameh4,Ove Hermansen10,Matthias Hill1,Ray L. Langenfelds3,Diane Ivy15,Simon O'Doherty2,Paul B. Krummel3,Michela Maione11,12,David M. Etheridge3,Lingxi Zhou16,Paul J. Fraser3,Ronald G. Prinn15,Ray F. Weiss4,and Peter G. Simmonds2
1Laboratory for Air Pollution and Environmental Technology, Empa, Swiss Federal Laboratories for Materials Science and Technology,
Überlandstrasse 129, 8600 Dübendorf, Switzerland
2Atmospheric Chemistry Research Group, School of Chemistry, University of Bristol, Bristol, UK
3Climate Science Centre, CSIRO Oceans and Atmosphere, Aspendale, Victoria, Australia
4Scripps Institution of Oceanography, University of California at San Diego, La Jolla, California, USA
5Kyungpook Institute of Oceanography, Kyungpook National University, South Korea
6METAS, Federal Institute of Metrology, Lindenweg 50, Bern-Wabern, Switzerland
7Earth System Research Laboratory, NOAA, Boulder, Colorado, USA
8Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA
9Meteorological Observation Centre (MOC), China Meteorological Administration (CMA), Beijing, China
10Norwegian Institute for Air Research, Kjeller, Norway
11Department of Pure and Applied Sciences, University of Urbino, Urbino, Italy
12Institute of Atmospheric Sciences and Climate, Italian National Research Council, Bologna, Italy
13Korea Polar Research Institute, KIOST, Incheon, South Korea
14School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
15Center for Global Change Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
16Chinese Academy of Meteorological Sciences (CAMS), China Meteorological Administration (CMA), Beijing, China
1Laboratory for Air Pollution and Environmental Technology, Empa, Swiss Federal Laboratories for Materials Science and Technology,
Überlandstrasse 129, 8600 Dübendorf, Switzerland
2Atmospheric Chemistry Research Group, School of Chemistry, University of Bristol, Bristol, UK
3Climate Science Centre, CSIRO Oceans and Atmosphere, Aspendale, Victoria, Australia
4Scripps Institution of Oceanography, University of California at San Diego, La Jolla, California, USA
5Kyungpook Institute of Oceanography, Kyungpook National University, South Korea
6METAS, Federal Institute of Metrology, Lindenweg 50, Bern-Wabern, Switzerland
7Earth System Research Laboratory, NOAA, Boulder, Colorado, USA
8Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA
9Meteorological Observation Centre (MOC), China Meteorological Administration (CMA), Beijing, China
10Norwegian Institute for Air Research, Kjeller, Norway
11Department of Pure and Applied Sciences, University of Urbino, Urbino, Italy
12Institute of Atmospheric Sciences and Climate, Italian National Research Council, Bologna, Italy
13Korea Polar Research Institute, KIOST, Incheon, South Korea
14School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
15Center for Global Change Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
16Chinese Academy of Meteorological Sciences (CAMS), China Meteorological Administration (CMA), Beijing, China
Correspondence: Martin K. Vollmer (martin.vollmer@empa.ch)
Received: 08 Oct 2017 – Discussion started: 10 Oct 2017 – Revised: 06 Dec 2017 – Accepted: 11 Dec 2017 – Published: 25 Jan 2018
Abstract. Based on observations of the chlorofluorocarbons CFC-13 (chlorotrifluoromethane), ΣCFC-114 (combined measurement of both isomers of dichlorotetrafluoroethane), and CFC-115 (chloropentafluoroethane) in atmospheric and firn samples, we reconstruct records of their tropospheric histories spanning nearly 8 decades. These compounds were measured in polar firn air samples, in ambient air archived in canisters, and in situ at the AGAGE (Advanced Global Atmospheric Gases Experiment) network and affiliated sites. Global emissions to the atmosphere are derived from these observations using an inversion based on a 12-box atmospheric transport model. For CFC-13, we provide the first comprehensive global analysis. This compound increased monotonically from its first appearance in the atmosphere in the late 1950s to a mean global abundance of 3.18 ppt (dry-air mole fraction in parts per trillion, pmol mol−1) in 2016. Its growth rate has decreased since the mid-1980s but has remained at a surprisingly high mean level of 0.02 ppt yr−1 since 2000, resulting in a continuing growth of CFC-13 in the atmosphere. ΣCFC-114 increased from its appearance in the 1950s to a maximum of 16.6 ppt in the early 2000s and has since slightly declined to 16.3 ppt in 2016. CFC-115 increased monotonically from its first appearance in the 1960s and reached a global mean mole fraction of 8.49 ppt in 2016. Growth rates of all three compounds over the past years are significantly larger than would be expected from zero emissions. Under the assumption of unchanging lifetimes and atmospheric transport patterns, we derive global emissions from our measurements, which have remained unexpectedly high in recent years: mean yearly emissions for the last decade (2007–2016) of CFC-13 are at 0.48 ± 0.15 kt yr−1 (> 15 % of past peak emissions), of ΣCFC-114 at 1.90 ± 0.84 kt yr−1 (∼ 10 % of peak emissions), and of CFC-115 at 0.80 ± 0.50 kt yr−1 (> 5 % of peak emissions). Mean yearly emissions of CFC-115 for 2015–2016 are 1.14 ± 0.50 kt yr−1 and have doubled compared to the 2007–2010 minimum. We find CFC-13 emissions from aluminum smelters but if extrapolated to global emissions, they cannot account for the lingering global emissions determined from the atmospheric observations. We find impurities of CFC-115 in the refrigerant HFC-125 (CHF2CF3) but if extrapolated to global emissions, they can neither account for the lingering global CFC-115 emissions determined from the atmospheric observations nor for their recent increases. We also conduct regional inversions for the years 2012–2016 for the northeastern Asian area using observations from the Korean AGAGE site at Gosan and find significant emissions for ΣCFC-114 and CFC-115, suggesting that a large fraction of their global emissions currently occur in northeastern Asia and more specifically on the Chinese mainland.
We measured the three chlorofluorocarbons (CFCs) CFC-13, CFC-114, and CFC-115 in the atmosphere because they are important in stratospheric ozone depletion. These compounds should have decreased in the atmosphere because they are banned by the Montreal Protocol but we find the opposite. Emissions over the last decade have not declined on a global scale. We use inverse modeling and our observations to find that a large part of the emissions originate in the Asian region.
We measured the three chlorofluorocarbons (CFCs) CFC-13, CFC-114, and CFC-115 in the atmosphere...