Isotopic data of atmospheric methane from EDML and Vostok ice cores over a full glacial cycle, supplement to: Möller, Lars; Sowers, Todd A; Bock, Michael; Spahni, Renato; Behrens, Melanie; Schmitt, Jochen; Miller, Heinz; Fischer, Hubertus (2013): Independent variations of CH4 emissions and isotopic composition over the past 160,000 years. Nature Geoscience, 6, 885-890

The response of natural CH4 sources to climate changes will be an important factor to consider as concentrations of this potent greenhouse gas continue to increase. Polar ice cores provide the means to assess this sensitivity in the past and have shown a close connection between CH4 levels and north...

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Bibliographic Details
Main Authors: Möller, Lars, Sowers, Todd A, Bock, Michael, Spahni, Renato, Behrens, Melanie, Schmitt, Jochen, Miller, Heinz, Fischer, Hubertus
Format: Article in Journal/Newspaper
Language:English
Published: PANGAEA - Data Publisher for Earth & Environmental Science 2013
Subjects:
European Project for Ice Coring in Antarctica EPICA
Todd
Antarc*
Antarctica
EPICA
ice core
Online Access:https://dx.doi.org/10.1594/pangaea.812116
https://doi.pangaea.de/10.1594/PANGAEA.812116
Description
Summary:The response of natural CH4 sources to climate changes will be an important factor to consider as concentrations of this potent greenhouse gas continue to increase. Polar ice cores provide the means to assess this sensitivity in the past and have shown a close connection between CH4 levels and northern hemisphere temperature variability over the last glacial cycle. However, the contribution of the various CH4 sources and sinks to these changes is still a matter of debate. Contemporaneous stable CH4 isotope records in ice cores provide additional boundary conditions for assessing changes in the CH4 sources and sinks. Here we present new ice core CH4 isotope data covering the last 160,000 years, showing a clear decoupling between CH4 loading and carbon isotopic variations over most of the record. We suggest that d13CH4 variations were not dominated by a change in the source mix but rather by climate- and CO2-related ecosystem control on the isotopic composition of the methane precursor material, especially in seasonally inundated wetlands in the tropics. In contrast, relatively stable d13CH4 intervals occurred during large CH4 loading changes concurrently with past climate changes implying that most CH4 sources (most notably tropical wetlands) responded simultaneously.

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