Anthropogenic Impacts on Tropospheric Reactive Chlorine Since the Preindustrial

Zhai, Shuting; Wang, Xuan; McConnell, Joseph R.; Geng, Lei; Cole-Dai, Jihong; Sigl, Michael; Chellman, Nathan; Sherwen, Tomás; Pound, Ryan; Fujita, Koji; Hattori, Shohei; Moch, Jonathan M.; Zhu, Lei; Evans, Mat; Legrand, Michel; Liu, Pengfei; Pasteris, Daniel; Chan, Yuk-Chun; Murray, Lee T. and Alexander, Becky (2021). Anthropogenic Impacts on Tropospheric Reactive Chlorine Since the Preindustrial. Geophysical Research Letters, 48(14), e2021GL093808. American Geophysical Union 10.1029/2021GL093808

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Tropospheric reactive gaseous chlorine (Cly) impacts the atmosphere’s oxidation capacity with implications for chemically reduced gases such as methane. Here we use Greenland ice-core records of chlorine, sodium, and acidity, and global model simulations to show how tropospheric Cly has been impacted by anthropogenic emissions since the 1940s. We show that anthropogenic contribution of non-sea-salt chlorine significantly influenced total chlorine and its trends after the 1940s. The modeled regional 170% Cly increase from preindustrial to the 1970s was driven by acid displacement from sea-salt-aerosol, direct emission of hydrochloric acid (HCl) from combustion, and chemical reactions driven by anthropogenic nitrogen oxide (NOx) emissions. Since the 1970s, the modeled 6% Cly decrease was caused mainly by reduced anthropogenic HCl emissions from air pollution mitigation policies. Our findings suggest that anthropogenic emissions of acidic gases and their emission control strategies have substantial impacts on Cly with implications for tropospheric oxidants, methane, and mercury.

Item Type:

Journal Article (Original Article)


08 Faculty of Science > Physics Institute > Climate and Environmental Physics

UniBE Contributor:

Sigl, Michael


500 Science > 530 Physics
500 Science > 540 Chemistry




American Geophysical Union




Michael Sigl

Date Deposited:

09 Nov 2021 12:03

Last Modified:

05 Dec 2022 15:53

Publisher DOI:





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