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

Fischer, Hubertus; Schüpbach, Simon; Gfeller, Gideon; Bigler, Matthias; Röthlisberger, Regine; Erhardt, Tobias; Stocker, Thomas F.; Mulvaney, Robert; 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. Nature Publishing Group 10.1038/ngeo2495

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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.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Physics Institute > Climate and Environmental Physics
10 Strategic Research Centers > Oeschger Centre for Climate Change Research (OCCR)

Graduate School:

Graduate School of Climate Sciences

UniBE Contributor:

Fischer, Hubertus; Schüpbach, Simon; Gfeller, Gideon; Bigler, Matthias; Erhardt, Tobias and Stocker, Thomas

Subjects:

500 Science > 530 Physics

ISSN:

1752-0894

Publisher:

Nature Publishing Group

Language:

English

Submitter:

Doris Rätz

Date Deposited:

18 Sep 2015 07:56

Last Modified:

02 Mar 2016 16:28

Publisher DOI:

10.1038/ngeo2495

BORIS DOI:

10.7892/boris.71406

URI:

https://boris.unibe.ch/id/eprint/71406

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