Sea ice and pollution-modulated changes in Greenland ice core methanesulfonate and bromine

Maselli, Olivia J. and Chellman, Nathan J. and Grieman, Mackenzie and Layman, Lawrence and McConnell, Joseph R. and Pasteris, Daniel and Rhodes, Rachael H. and Saltzman, Eric and Sigl, Michael (2017) Sea ice and pollution-modulated changes in Greenland ice core methanesulfonate and bromine. Climate of the past, 13 (1). pp. 39-59. ISSN 1814-9340 DOI 10.5194/cp-13-39-2017

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Official URL: http://doi.org/10.5194/cp-13-39-2017

Abstract

Reconstruction of past changes in Arctic sea ice extent may be critical for understanding its future evolution. Methanesulfonate (MSA) and bromine concentrations preserved in ice cores have both been proposed as indicators of past sea ice conditions. In this study, two ice cores from central and north-eastern Greenland were analysed at sub-annual resolution for MSA (CH3SO3H) and bromine, covering the time period 1750–2010. We examine correlations between ice core MSA and the HadISST1 ICE sea ice dataset and consult back trajectories to infer the likely source regions. A strong correlation between the low-frequency MSA and bromine records during pre-industrial times indicates that both chemical species are likely linked to processes occurring on or near sea ice in the same source regions. The positive correlation between ice core MSA and bromine persists until the mid-20th century, when the acidity of Greenland ice begins to increase markedly due to increased fossil fuel emissions. After that time, MSA levels decrease as a result of declining sea ice extent but bromine levels increase. We consider several possible explanations and ultimately suggest that increased acidity, specifically nitric acid, of snow on sea ice stimulates the release of reactive Br from sea ice, resulting in increased transport and deposition on the Greenland ice sheet.

Item Type: Article
Uncontrolled Keywords: 2016AREP, IA72
Subjects: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions: 01 - Climate Change and Earth-Ocean Atmosphere Systems
07 - Gold Open Access
Journal or Publication Title: Climate of the past
Volume: 13
Page Range: pp. 39-59
Identification Number: 10.5194/cp-13-39-2017
Depositing User: Sarah Humbert
Date Deposited: 07 Apr 2017 23:18
Last Modified: 07 Apr 2017 23:18
URI: http://eprints.esc.cam.ac.uk/id/eprint/3885

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