Document Detail

Increased terrestrial methane cycling at the Palaeocene-Eocene thermal maximum.
MedLine Citation:
PMID:  17882218     Owner:  NLM     Status:  MEDLINE    
The Palaeocene-Eocene thermal maximum (PETM), a period of intense, global warming about 55 million years ago, has been attributed to a rapid rise in greenhouse gas levels, with dissociation of methane hydrates being the most commonly invoked explanation. It has been suggested previously that high-latitude methane emissions from terrestrial environments could have enhanced the warming effect, 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 PETM and therefore provides an opportunity to examine the biogeochemical response of wetland-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 and wetter climate. Our data suggest that the release of methane from the terrestrial biosphere increased and possibly acted as a positive feedback mechanism to global warming.
Richard D Pancost; David S Steart; Luke Handley; Margaret E Collinson; Jerry J Hooker; Andrew C Scott; Nathalie V Grassineau; Ian J Glasspool
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Publication Detail:
Type:  Historical Article; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Nature     Volume:  449     ISSN:  1476-4687     ISO Abbreviation:  Nature     Publication Date:  2007 Sep 
Date Detail:
Created Date:  2007-09-20     Completed Date:  2007-10-12     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0410462     Medline TA:  Nature     Country:  England    
Other Details:
Languages:  eng     Pagination:  332-5     Citation Subset:  IM    
Organic Geochemistry Unit, Bristol Biogeochemistry Research Centre, School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
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MeSH Terms
Bacteria / metabolism
Carbon Isotopes
Greenhouse Effect*
History, Ancient
Methane / chemistry,  metabolism*
Time Factors
Reg. No./Substance:
0/Carbon Isotopes; 74-82-8/Methane

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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