title: Atmospheric methane and nitrous oxide of the Late Pleistocene from Antarctic ice cores.
abstract: The European Project for Ice Coring in Antarctica Dome C ice core enables us to extend existing records of atmospheric methane (CH4) and nitrous oxide (N2O) back to 650,000 years before the present. A combined record of CH4 measured along the Dome C and the Vostok ice cores demonstrates, within the resolution of our measurements, that preindustrial concentrations over Antarctica have not exceeded 773 +/- 15 ppbv (parts per billion by volume) during the past 650,000 years. Before 420,000 years ago, when interglacials were cooler, maximum CH4 concentrations were only about 600 ppbv, similar to lower Holocene values. In contrast, the N2O record shows maximum concentrations of 278 +/- 7 ppbv, slightly higher than early Holocene values.
authors.affiliation: Climate and Environmental Physics, Physics Institute, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland.
authors.forename: Renato
authors.initials: R
authors.lastname: Spahni
authors.forename: Jérôme
authors.initials: J
authors.lastname: Chappellaz
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Stocker
authors.forename: Laetitia
authors.initials: L
authors.lastname: Loulergue
authors.forename: Gregor
authors.initials: G
authors.lastname: Hausammann
authors.forename: Kenji
authors.initials: K
authors.lastname: Kawamura
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Flückiger
authors.forename: Jakob
authors.initials: J
authors.lastname: Schwander
authors.forename: Dominique
authors.initials: D
authors.lastname: Raynaud
authors.forename: Valérie
authors.initials: V
authors.lastname: Masson-Delmotte
authors.forename: Jean
authors.initials: J
authors.lastname: Jouzel