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Originally published in Science Express on 9 August 2007
Science 7 September 2007:
Vol. 317. no. 5843, pp. 1381 - 1384
DOI: 10.1126/science.1144856
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Reports

20th-Century Industrial Black Carbon Emissions Altered Arctic Climate Forcing

Joseph R. McConnell,1* Ross Edwards,1 Gregory L. Kok,2 Mark G. Flanner,3 Charles S. Zender,3 Eric S. Saltzman,3 J. Ryan Banta,1 Daniel R. Pasteris,1 Megan M. Carter,4 Jonathan D. W. Kahl4

Black carbon (BC) from biomass and fossil fuel combustion alters chemical and physical properties of the atmosphere and snow albedo, yet little is known about its emission or deposition histories. Measurements of BC, vanillic acid, and non–sea-salt sulfur in ice cores indicate that sources and concentrations of BC in Greenland precipitation varied greatly since 1788 as a result of boreal forest fires and industrial activities. Beginning about 1850, industrial emissions resulted in a sevenfold increase in ice-core BC concentrations, with most change occurring in winter. BC concentrations after about 1951 were lower but increasing. At its maximum from 1906 to 1910, estimated surface climate forcing in early summer from BC in Arctic snow was about 3 watts per square meter, which is eight times the typical preindustrial forcing value.

1 Desert Research Institute, Nevada System of Higher Education, Reno, NV 89512, USA.
2 Droplet Measurement Technologies, Boulder, CO 80301, USA.
3 Department of Earth System Science, University of California, Irvine, CA 92697, USA.
4 Department of Mathematical Sciences, University of Wisconsin–Milwaukee, Milwaukee, WI 53201, USA.

* To whom correspondence should be addressed. E-mail: Joe.McConnell{at}dri.edu

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Coal burning leaves toxic heavy metal legacy in the Arctic.
J. R. McConnell and R. Edwards (2008)
PNAS 105, 12140-12144
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