[Source: Proceedings of the National Academy of Sciences of the United States of America, full page: (LINK). Abstract, edited.]
Pervasive Arctic lead pollution suggests substantial growth in medieval silver production modulated by plague, climate, and conflict
Joseph R. McConnell, Nathan J. Chellman, Andrew I. Wilson, Andreas Stohl, Monica M. Arienzo, Sabine Eckhardt, Diedrich Fritzsche, Sepp Kipfstuhl, Thomas Opel, Philip F. Place, and Jørgen Peder Steffensen
PNAS first published July 8, 2019 / DOI: https://doi.org/10.1073/pnas.1904515116
Edited by Eric W. Wolff, University of Cambridge, Cambridge, United Kingdom, and accepted by Editorial Board Member A. R. Ravishankara June 13, 2019 (received for review March 15, 2019)
Detailed lead pollution measurements in an array of 13 ice cores spanning nearly half the Arctic showed surprisingly similar temporal variability during the past 2 millennia until the Industrial Revolution. Lead pollution increased by 250- to 300-fold from the Early Middle Ages to the 1970s industrial peak, reflecting large-scale emissions changes from ancient European silver production, recent fossil fuel burning, and other industrial activities. Pronounced decadal-scale increases coincided with exploitation of new mining districts, technology development, and periods of economic prosperity, while decreases coincided with climate disruptions, famines, major wars, and plagues. Despite midlatitude pollution abatement policies that reduced Arctic lead pollution by >80% since the 1970s, recent levels remain 60-fold higher than at the start of the Middle Ages.
Lead pollution in Arctic ice reflects large-scale historical changes in midlatitude industrial activities such as ancient lead/silver production and recent fossil fuel burning. Here we used measurements in a broad array of 13 accurately dated ice cores from Greenland and Severnaya Zemlya to document spatial and temporal changes in Arctic lead pollution from 200 BCE to 2010 CE, with interpretation focused on 500 to 2010 CE. Atmospheric transport modeling indicates that Arctic lead pollution was primarily from European emissions before the 19th-century Industrial Revolution. Temporal variability was surprisingly similar across the large swath of the Arctic represented by the array, with 250- to 300-fold increases in lead pollution observed from the Early Middle Ages to the 1970s industrial peak. Superimposed on these exponential changes were pronounced, multiannual to multidecadal variations, marked by increases coincident with exploitation of new mining regions, improved technologies, and periods of economic prosperity; and decreases coincident with climate disruptions, famines, major wars, and plagues. Results suggest substantial overall growth in lead/silver mining and smelting emissions—and so silver production—from the Early through High Middle Ages, particularly in northern Europe, with lower growth during the Late Middle Ages into the Early Modern Period. Near the end of the second plague pandemic (1348 to ∼1700 CE), lead pollution increased sharply through the Industrial Revolution. North American and European pollution abatement policies have reduced Arctic lead pollution by >80% since the 1970s, but recent levels remain ∼60-fold higher than at the start of the Middle Ages.
ice core – lead pollution – Arctic – plague – Middle Ages
1 To whom correspondence may be addressed. Email: Joe.McConnell@dri.edu.
Author contributions: J.R.M. designed research; J.R.M., N.J.C., A.S., M.M.A., S.E., D.F., S.K., T.O., P.F.P., and J.P.S. performed research; J.R.M., N.J.C., A.I.W., and A.S. analyzed data; and J.R.M., N.J.C., A.I.W., and A.S. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission. E.W.W. is a guest editor invited by the Editorial Board.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1904515116/-/DCSupplemental.
Published under the PNAS license.
Keywords: Arctic; Environmental Pollution; Middle Age; Plague; Wars.