Millennial changes in North American wildfire and soil activity over the last glacial cycle

Fischer, Hubertus and Schüpbach, Simon and Gfeller, Gideon and Bigler, Matthias and Röthlisberger, Regine and Erhardt, Tobias and Stocker, Thomas F. and Mulvaney, Robert and Wolff, Eric W. (2015) Millennial changes in North American wildfire and soil activity over the last glacial cycle. Nature Geoscience, 8 (9). pp. 723-727. ISSN 1752-0894 EISSN:1752-0908 DOI 10.1038/ngeo2495

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Abstract

Climate changes in the North Atlantic region during the last glacial cycle were dominated by the slow waxing and waning of the North American ice sheet as well as by intermittent, millennial-scale Dansgaard-Oeschger climate oscillations. However, prior to the last deglaciation, the responses of North American vegetation and biomass burning to these climate variations are uncertain. Ammonium in Greenland ice cores, a product from North American soil emissions and biomass burning events, can help to fill this gap. Here we use continuous, high-resolution measurements of ammonium concentrations between 110,000 to 10,000 years ago from the Greenland NGRIP and GRIP ice cores to reconstruct North American wildfire activity and soil ammonium emissions. We find that on orbital timescales soil emissions increased under warmer climate conditions when vegetation expanded northwards into previously ice-covered areas. For millennial-scale interstadial warm periods during Marine Isotope Stage 3, the fire recurrence rate increased in parallel to the rapid warmings, whereas soil emissions rose more slowly, reflecting slow ice shrinkage and delayed ecosystem changes. We conclude that sudden warming events had little impact on soil ammonium emissions and ammonium transport to Greenland, but did result in a substantial increase in the frequency of North American wildfires. View full text

Item Type: Article
Uncontrolled Keywords: 2015AREP; IA69; weekly list
Subjects: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Journal or Publication Title: Nature Geoscience
Volume: 8
Page Range: pp. 723-727
Identification Number: 10.1038/ngeo2495
Depositing User: Sarah Humbert
Date Deposited: 08 Jan 2016 19:33
Last Modified: 08 Jan 2016 19:33
URI: http://eprints.esc.cam.ac.uk/id/eprint/3517

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