ABSTRACT An industrial-era decline in Greenland ice-core methanesulfonic acid is thought to herald a collapse in North Atlantic marine phytoplankton stocks related to a weakening of the

Atlantic meridional overturning circulation. By contrast, stable levels of total marine biogenic sulfur contradict this interpretation and point to changes in atmospheric oxidation as a

potential cause of the methanesulfonic acid decline. However, the impact of oxidation on methanesulfonic acid production has not been quantified, nor has this hypothesis been rigorously

tested. Here we present a multi-century methanesulfonic acid record from the Denali, Alaska, ice core, which shows a methanesulfonic acid decline similar in magnitude but delayed by 93 years

timing of the North Pacific methanesulfonic acid decline, relative to the North Atlantic, reflects the distinct history of industrialization in upwind regions and is consistent with the

Denali and Greenland ice-core nitrate records. These results demonstrate that multidecadal trends in industrial-era Arctic ice-core methanesulfonic acid reflect rising anthropogenic

pollution rather than declining marine primary production. Access through your institution Buy or subscribe This is a preview of subscription content, access via your institution ACCESS

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FAQs * Contact customer support SIMILAR CONTENT BEING VIEWED BY OTHERS CHANGES IN GLOBAL DMS PRODUCTION DRIVEN BY INCREASED CO2 LEVELS AND ITS IMPACT ON RADIATIVE FORCING Article Open access

12 January 2024 INCREASED OCEANIC DIMETHYL SULFIDE EMISSIONS IN AREAS OF SEA ICE RETREAT INFERRED FROM A GREENLAND ICE CORE Article Open access 26 December 2022 LIMITED DECREASE OF SOUTHERN

OCEAN SULFUR PRODUCTIVITY ACROSS THE PENULTIMATE TERMINATION Article 03 January 2025 DATA AVAILABILITY Denali ice-core (DEN13A and DEN13B) MSA data are available from the Arctic Data Center

(https://doi.org/10.18739/A2Q814T9K). The Greenland MSA composite record is available from ref. 10, and Summit07 MSA data are available from ref. 22. Denali NO3– is available at the

National Oceanic and Atmospheric Administration (NOAA) palaeoclimatology database (https://doi.org/10.25921/6cpm-kr44), and Summit07 NO3– is available from ref. 49. GEOS-Chem output is from

ref. 54. CEDS emissions data used in this study are from ref. 30. All data shown in the Main and Extended Data Figures are available at the preceding references or can be recreated following

the Code Availability Statement. CODE AVAILABILITY The F0AM source code can be downloaded from https://github.com/AirChem/F0AM. Gas-phase MSA mechanisms were implemented following reactions

listed in Supplementary Tables 1–4. GEOS-Chem source code can be downloaded from https://github.com/geoschem/geos-chem/tree/13.2.1. Code for Bayesian changepoint analysis was modified from

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Scholar  Download references ACKNOWLEDGEMENTS Retrieval and analysis of the Denali ice core is supported by the National Science Foundation (NSF) Paleo Perspectives on Climate Change Program

(P2C2), grants AGS-1204035 (E.C.O.), AGS-1203838 (K.J.K.) and AGS-1203863 (C.P.W.). Denali National Park and Preserve, Polar Field Services and Talkeetna Air Taxi provided aircraft support

and field logistical assistance. We thank M. Waszkiewicz, S. Campbell, B. Markle, E. Burakowski, D. Silverstone and T. Godaire for field assistance, and over 25 students for their assistance

sampling and analysing the Denali ice cores in the Dartmouth Ice, Climate, and Environment Laboratory. The Denali ice cores were processed at the NSF Ice Core Facility in Denver, Colorado.

J.I.C. acknowledges travel support from the Dartmouth Dickey Center. NSF grants PLR-1904128 (B.A.), PLR-2230350 (B.A.) and AGS-2202287 (B.A.) supported analysis of the Summit07 ice core.

AUTHOR INFORMATION AUTHORS AND AFFILIATIONS * Department of Earth Sciences, Dartmouth College, Hanover, NH, USA Jacob I. Chalif, Erich C. Osterberg & David G. Ferris * Department of

Atmospheric and Climate Science, University of Washington, Seattle, WA, USA Ursula A. Jongebloed & Becky Alexander * Department of Geology, Colby College, Waterville, ME, USA Bess G.

Koffman * Climate Change Institute and School of Earth and Climate Sciences, University of Maine, Orono, ME, USA Dominic A. Winski & Karl J. Kreutz * Department of Geosciences,

University of Alaska, Fairbanks, AK, USA David J. Polashenski * Bigelow Laboratory for Ocean Sciences, East Boothbay, ME, USA Karen Stamieszkin * Center for North Atlantic Studies,

University of New England, Portland, ME, USA Cameron P. Wake * Department of Chemistry and Biochemistry, South Dakota State University, Brookings, SD, USA Jihong Cole-Dai Authors * Jacob I.

Chalif View author publications You can also search for this author inPubMed Google Scholar * Ursula A. Jongebloed View author publications You can also search for this author inPubMed 

Google Scholar * Erich C. Osterberg View author publications You can also search for this author inPubMed Google Scholar * Bess G. Koffman View author publications You can also search for

this author inPubMed Google Scholar * Becky Alexander View author publications You can also search for this author inPubMed Google Scholar * Dominic A. Winski View author publications You

can also search for this author inPubMed Google Scholar * David J. Polashenski View author publications You can also search for this author inPubMed Google Scholar * Karen Stamieszkin View

author publications You can also search for this author inPubMed Google Scholar * David G. Ferris View author publications You can also search for this author inPubMed Google Scholar * Karl

J. Kreutz View author publications You can also search for this author inPubMed Google Scholar * Cameron P. Wake View author publications You can also search for this author inPubMed Google

Scholar * Jihong Cole-Dai View author publications You can also search for this author inPubMed Google Scholar CONTRIBUTIONS J.I.C. and U.A.J. conceived of and carried out this study.

E.C.O., B.G.K. and B.A. provided critical guidance and input throughout. E.C.O., K.J.K. and C.P.W. wrote the initial proposal to drill and chemically analyse the Denali ice core. D.G.F.

melted the core and, with D.A.W. and E.C.O., developed the timescale. J.C.-D. obtained funding to drill and measure major ions, including MSA and NO3–, in the Summit07 ice core. K.S. and

B.G.K. developed a set of initial hypotheses for MSA decline, and K.S. and D.J.P. investigated linkages between Denali MSA and North Pacific production. J.I.C. wrote the paper with input

from E.C.O., B.G.K. and U.A.J. All authors discussed the results and reviewed the manuscript. CORRESPONDING AUTHOR Correspondence to Jacob I. Chalif. ETHICS DECLARATIONS COMPETING INTERESTS

The authors declare no competing interests. PEER REVIEW PEER REVIEW INFORMATION _Nature Geoscience_ thanks Alex Archibald, M. Anwar Khan and the other, anonymous, reviewer(s) for their

contribution to the peer review of this work. Primary Handling Editor: Xujia Jiang, in collaboration with the _Nature Geoscience_ team. ADDITIONAL INFORMATION PUBLISHER’S NOTE Springer

Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. EXTENDED DATA EXTENDED DATA FIG. 1 ICE CORE MSA RECORDS WITH CHANGEPOINT

PROBABILITY. (A) Denali MSA changepoint probability, based on an irregular Bayesian changepoint analysis (see Methods). The likeliest changepoint year (1962) indicated by a vertical dark

orange dashed line. (B) Denali MSA. (C) The Greenland composite MSA records, with the record’s 50th percentile (dark blue) and 95% confidence interval (light blue) given10. (D) Greenland MSA

changepoint probability, with the three likeliest changepoint years (1854, 1869, and 1953) indicated by vertical dark blue dashed lines. EXTENDED DATA FIG. 2 F0AM BOX MODEL RESULTS,

INCLUDING ROSS SEA, ANTARCTICA. (A) The PI–IE percent change in MSA under several F0AM model runs, using atmospheric oxidant concentrations from the Denali source region (orange), the

Greenland source region (blue), and the Ross Sea, Antarctica (green). The shapes represent the different DMS oxidation mechanisms we used. The APC (leftmost) column shows the change in MSA

when all oxidants and temperature (that is, ‘parameters’) change from the PI to the IE. The columns to the right show the change when one parameter is held constant from the PI to the IE and

the rest are allowed to change (CNSTp). (B) The MSA-impact score, which is the fraction change between CNSTp and APC. The magnitude of the MSA-impact score represents the oxidative effect

of the increase of each parameter from the PI to the IE. Note that the impacts of O3 and OH in the Ross Sea is unusually high because the Ross Sea APC is close to 0. (C) An alternative

calculation of MSA impact (MSA-delta), calculated by the difference between CNSTp and APC, which corrects the unusually high Ross Sea MSA-impact score in (B). EXTENDED DATA FIG. 3 DENALI MSA

FROM CORES 1 AND 2. The MSA record from Denali core 2 (orange; this study) and core 1 (red). Core 1 was only analyzed to 1866 and its raw record contains anomalous dips to near 0, leading

to an overall lower annual average than core 2. Despite the data issues, core 1 contains a mean decline in MSA of 1.79 ppb from 1962–2011 compared with 1866–1961. Core 2, likewise, contains

a mean drop of 1.77 ppb over the same period. EXTENDED DATA FIG. 4 F0AM MODEL PARAMETER SENSITIVITY TESTING OF THE DENALI SOURCE REGION. These are model runs in which all parameters (that

is, oxidant concentrations and temperature) change from PI to IE, using the Fung mechanism. The red markers indicate the mean modeled changes for the Denali source region. Each panel shows

the sensitivity of the model to different selections of the labeled parameter. See Methods for details. EXTENDED DATA FIG. 5 F0AM MODEL PARAMETER SENSITIVITY TESTING OF THE GREENLAND SOURCE

REGION. As with Extended Data Fig. 4, but with the Greenland MSA source region. SUPPLEMENTARY INFORMATION SUPPLEMENTARY INFORMATION Supplementary Figs. 1–4, Tables 1–5, discussion and

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permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Chalif, J.I., Jongebloed, U.A., Osterberg, E.C. _et al._ Pollution drives multidecadal decline in subarctic methanesulfonic acid. _Nat.

Geosci._ 17, 1016–1021 (2024). https://doi.org/10.1038/s41561-024-01543-w Download citation * Received: 15 January 2024 * Accepted: 22 August 2024 * Published: 23 September 2024 * Issue

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