EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Centennial-scale evolution of methane during the penultimate deglaciation

Loïc Schmidely1, Lucas Silva1, Christoph Nehrbass-Ahles2, Juhyeong Han1, Jinhwa Shin3, Jochen Schmitt1, Hubertus Fischer1, and Thomas Stocker1
Loïc Schmidely et al.
  • 1University of Bern, Physics Institute, Climate and Environmental Physics, Switzerland (
  • 2Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ UK
  • 3CNRS, Univ. Grenoble-Alpes, Institut des Géosciences de l’Environnement (IGE), Grenoble, France

Small air inclusions in ice cores represent a direct archive of past atmospheric compositions, allowing us to measure the concentration of the three most potent non-condensable Greenhouse Gases (GHG) CO2, CH4 and N2O as far back as 800,000 years before present (kyr BP). These records demonstrate that transitions from glacial to interglacial conditions are accompanied by a substantial net increase of CO2, CH4 and N2O in the atmosphere (Lüthi et al. 2008, Loulergue et al. 2008, Schilt et al. 2010). A sound understanding of the interplay between the reorganization of the climate system and the perturbation of GHG inventories during glacial terminations is partly limited by the temporal resolution of the records derived from ice cores. In fact, with the exception of the last deglaciation (23-9 kyr BP) centennial-scale GHG variability remained uncaptured for precedings glacial terminations.

In this work, we exploit the exceptionally long temporal coverage of the EPICA Dome C (EDC) ice core to reconstruct, for the first time, centennial-scale fluctuations of CH4 mole fractions from 145 to 125 kyr BP, encompassing the entire penultimate deglaciation (138-128 kyr BP). With a temporal resolution of ~100 years, our new record is now unveiling all climate-driven signals enclosed into the EDC ice core, exploiting the maximum resolution possible at Dome C (). This offers us the opportunity to study the timing and rates of change of CH4 in unprecedented details.

Preliminary analysis reveals that the deglacial CH4 rise is a superimposition of gradual millennial-scale increases (~0.01-0.02 ppb/year) and abrupt and partly intermittent centennial-scale events (~80-200 ppb in less than a millennium). We will investigate processes modulating the observed changes in the CH4 cycle, compare the structure of our record with the CH4 profile of the last deglaciation (Marcott, 2014) and contrast it with the EDC CO2 and N2O records over the penultimate glacial termination now available in similar resolution.

How to cite: Schmidely, L., Silva, L., Nehrbass-Ahles, C., Han, J., Shin, J., Schmitt, J., Fischer, H., and Stocker, T.: Centennial-scale evolution of methane during the penultimate deglaciation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2844,, 2020

This abstract will not be presented.