Ice Record of 
13C for Atmospheric CH4 Across the Younger Dryas-Preboreal Transition
Hinrich Schaefer,1,2*
Michael J. Whiticar,1
Edward J. Brook,2
Vasilii V. Petrenko,3
Dominic F. Ferretti,4,5
Jeffrey P. Severinghaus3
We report atmospheric methane carbon isotope ratios (
13CH4) from the Western Greenland ice margin spanning the Younger Dryas–to–Preboreal (YD-PB) transition. Over the recorded 
800 years, 13CH4 was around –46 per mil (
); that is, 1 higher than in the modern atmosphere and 5.5 higher than would be expected from budgets without 13C-rich anthropogenic emissions. This requires higher natural 13C-rich emissions or stronger sink fractionation than conventionally assumed. Constant 13CH4 during the rise in methane concentration at the YD-PB transition is consistent with additional emissions from tropical wetlands, or aerobic plant CH4 production, or with a multisource scenario. A marine clathrate source is unlikely.
1 School of Earth and Ocean Sciences, University of Victoria, Post Office Box 3055, V8W 3P6, Canada.
2 Department of Geosciences, Oregon State University, 104 Wilkinson Hall, Corvallis, OR 97331, USA.
3 Scripps Institution of Oceanography, University of California, San Diego, Mail Code 0244, La Jolla, CA 92093, USA.
4 Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO 80309, USA.
5 National Institute of Water and Atmospheric Research Limited, Post Office Box 14901, Wellington, New Zealand.
* To whom correspondence should be addressed. E-mail: schaefeh{at}geo.oregonstate.edu
