A growing threat to the ozone layer from short-lived anthropogenic chlorocarbons

Oram, David E. and Ashfold, Matthew J. and Laube, Johannes C. and Gooch, Lauren J. and Humphrey, Stephen and Sturges, William T. and Leedham-Elvidge, Emma and Forster, Grant L. and Harris, Neil R.P. and Mead, Mohammed Iqbal and Samah, Azizan Abu and Phang, Siew Moi and Ou-Yang, Chang-Feng and Lin, Neng-Huei and Wang, Jia-Lin and Baker, Angela K. and Brenninkmeijer, Carl A.M. and Sherry, David (2017) A growing threat to the ozone layer from short-lived anthropogenic chlorocarbons. Atmospheric Chemistry and Physics, 17 (19). pp. 11929-11941. ISSN 1680-7324, DOI https://doi.org/10.5194/acp-17-11929-2017.

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Abstract

Large and effective reductions in emissions of long-lived ozone-depleting substance (ODS) are being achieved through the Montreal Protocol, the effectiveness of which can be seen in the declining atmospheric abundances of many ODSs. An important remaining uncertainty concerns the role of very short-lived substances (VSLSs) which, owing to their relatively short atmospheric lifetimes (less than 6 months), are not regulated under the Montreal Protocol. Recent studies have found an unexplained increase in the global tropospheric abundance of one VSLS, dichloromethane (CH2Cl2), which has increased by around 60% over the past decade. Here we report dramatic enhancements of several chlorine-containing VSLSs (Cl-VSLSs), including CH2Cl2 and CH2ClCH2Cl (1,2-dichloroethane), observed in surface and upper-tropospheric air in East and South East Asia. Surface observations were, on occasion, an order of magnitude higher than previously reported in the marine boundary layer, whilst upper-tropospheric data were up to 3 times higher than expected. In addition, we provide further evidence of an atmospheric transport mechanism whereby substantial amounts of industrial pollution from East Asia, including these chlorinated VSLSs, can rapidly, and regularly, be transported to tropical regions of the western Pacific and subsequently uplifted to the tropical upper troposphere. This latter region is a major provider of air entering the stratosphere, and so this mechanism, in conjunction with increasing emissions of Cl-VSLSs from East Asia, could potentially slow the expected recovery of stratospheric ozone.

Item Type:	Article
Funders:	UK Natural Environment Research Council (NERC) International Opportunities Fund (NE/J016012/1, NE/J016047/1, NE/N006836/1), European FP7 project SHIVA (226224), Malaysian Ministry of Higher Education (Grant MOHE-HICoE IOES-2014), Taiwan EPA and MOST, NERC fellowship (NE/1021918/1) and studentship (NE/1210143)
Uncontrolled Keywords:	Atmospheric transport; Emission control; Industrial emission; Montreal Protocol; Ozone; Ozone depletion; Stratosphere; Troposphere
Subjects:	Q Science > Q Science (General)
Divisions:	Faculty of Arts and Social Sciences Faculty of Science
Depositing User:	Ms. Juhaida Abd Rahim
Date Deposited:	03 Sep 2018 08:08
Last Modified:	03 Dec 2019 11:35
URI:	http://eprints.um.edu.my/id/eprint/19068

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