Independent variations of CH₄ emissions and isotopic composition over the past 160,000 years

Möller, Lars; Sowers, Todd; Bock, Michael; Spahni, Renato; Behrens, Melanie; Schmitt, Jochen; Miller, Heinrich; Fischer, Hubertus (2013). Independent variations of CH₄ emissions and isotopic composition over the past 160,000 years. Nature geoscience, 6(10), pp. 885-890. Nature Publishing Group 10.1038/ngeo1922

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During the last glacial cycle, greenhouse gas concentrations fluctuated on decadal and longer timescales. Concentrations of methane, as measured in polar ice cores, show a close connection with Northern Hemisphere temperature variability, but the contribution of the various methane sources and sinks to changes in concentration is still a matter of debate. Here we assess changes in methane cycling over the past 160,000 years by measurements of the carbon isotopic composition delta C-13 of methane in Antarctic ice cores from Dronning Maud Land and Vostok. We find that variations in the delta C-13 of methane are not generally correlated with changes in atmospheric methane concentration, but instead more closely correlated to atmospheric CO2 concentrations. We interpret this to reflect a climatic and CO2-related control on the isotopic signature of methane source material, such as ecosystem shifts in the seasonally inundated tropical wetlands that produce methane. In contrast, relatively stable delta C-13 values occurred during intervals of large changes in the atmospheric loading of methane. We suggest that most methane sources-most notably tropical wetlands-must have responded simultaneously to climate changes across these periods.

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)

UniBE Contributor:

Bock, Michael; Spahni, Renato; Schmitt, Jochen and Fischer, Hubertus

Subjects:

500 Science > 530 Physics

ISSN:

1752-0894

Publisher:

Nature Publishing Group

Language:

English

Submitter:

Doris Rätz

Date Deposited:

29 Sep 2014 11:29

Last Modified:

10 Sep 2015 10:22

Publisher DOI:

10.1038/ngeo1922

Web of Science ID:

000325003700024

BORIS DOI:

10.7892/boris.47732

URI:

https://boris.unibe.ch/id/eprint/47732

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