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Increased terrestrial methane cycling at the Palaeocene-Eocene thermal maximum

Lookup NU author(s): Dr Luke Handley


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The Palaeocene-Eocene thermal maximum (PETM), a period of intense, global warming about 55 million years ago(1), has been attributed to a rapid rise in greenhouse gas levels, with dissociation of methane hydrates being the most commonly invoked explanation(2). It has been suggested previously that high-latitude methane emissions from terrestrial environments could have enhanced the warming effect(3,4), but direct evidence for an increased methane flux from wetlands is lacking. The Cobham Lignite, a recently characterized expanded lacustrine/mire deposit in England, spans the onset of the PETM5 and therefore provides an opportunity to examine the biogeochemical response of wet-land-type ecosystems at that time. Here we report the occurrence of hopanoids, biomarkers derived from bacteria, in the mire sediments from Cobham. We measure a decrease in the carbon isotope values of the hopanoids at the onset of the PETM interval, which suggests an increase in the methanotroph population. We propose that this reflects an increase in methane production potentially driven by changes to a warmer(1,6) and wetter climate(7,8). Our data suggest that the release of methane from the terrestrial biosphere increased and possibly acted as a positive feedback mechanism to global warming.

Publication metadata

Author(s): Pancost RD, Steart DS, Handley L, Collinson ME, Hooker JJ, Scott AC, Grassineau NV, Glasspool IJ

Publication type: Article

Publication status: Published

Journal: Nature

Year: 2007

Volume: 449

Issue: 7160

Pages: 332-335

ISSN (print): 0028-0836

ISSN (electronic): 1476-4687

Publisher: Nature Publishing Group


DOI: 10.1038/nature06012


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