TY - JOUR T1 - Ice Record of δ<sup>13</sup>C for Atmospheric CH<sub>4</sub> Across the Younger Dryas-Preboreal Transition JF - Science JO - Science SP - 1109 LP - 1112 DO - 10.1126/science.1126562 VL - 313 IS - 5790 AU - Schaefer, Hinrich AU - Whiticar, Michael J. AU - Brook, Edward J. AU - Petrenko, Vasilii V. AU - Ferretti, Dominic F. AU - Severinghaus, Jeffrey P. Y1 - 2006/08/25 UR - http://science.sciencemag.org/content/313/5790/1109.abstract N2 - We report atmospheric methane carbon isotope ratios (δ13CH4) from the Western Greenland ice margin spanning the Younger Dryas–to–Preboreal (YD-PB) transition. Over the recorded ∼800 years, δ13CH4 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 δ13CH4 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. ER -