Response of methane emissions from wetlands to the Last Glacial Maximum and an idealized Dansgaard-Oeschger climate event: insights from two models of different complexity

• Published in: Climate of the Past
• Main Authors: RINGEVAL, Bruno, Hopcroft, P., Valdes, P., Ciais, P., Ramstein, G., Dolman, A., Kageyama, M.
• Other Authors: Interactions Sol Plante Atmosphère (UMR ISPA), Institut National de la Recherche Agronomique (INRA)-Ecole Nationale Supérieure des Sciences Agronomiques de Bordeaux-Aquitaine (Bordeaux Sciences Agro), School of Geographical Sciences Bristol, University of Bristol Bristol, Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), ICOS-ATC (ICOS-ATC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Modélisation du climat (CLIM), Faculty of Earth and Life Sciences Amsterdam (FALW), Vrije Universiteit Amsterdam Amsterdam (VU)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2013
• Subjects: [SDE.MCG]Environmental Sciences/Global Changes; [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology; ice core
• Online Access: https://hal.archives-ouvertes.fr/hal-01806756; https://hal.archives-ouvertes.fr/hal-01806756/document; https://hal.archives-ouvertes.fr/hal-01806756/file/Ringeval_2013_CP.pdf; https://doi.org/10.5194/cp-9-149-2013

International audience The role of different sources and sinks of CH 4 in changes in atmospheric methane ([CH 4 ]) concentration during the last 100 000 yr is still not fully understood. In particular , the magnitude of the change in wetland CH 4 emissions at the Last Glacial Maximum (LGM) relative to the pre-industrial period (PI), as well as during abrupt climatic warming or Dansgaard–Oeschger (D–O) events of the last glacial period, is largely unconstrained. In the present study, we aim to understand the uncertainties related to the param-eterization of the wetland CH 4 emission models relevant to these time periods by using two wetland models of different complexity (SDGVM and ORCHIDEE). These models have been forced by identical climate fields from low-resolution coupled atmosphere–ocean general circulation model (FAMOUS) simulations of these time periods. Both emission models simulate a large decrease in emissions during LGM in comparison to PI consistent with ice core observations and previous modelling studies. The global reduction is much larger in ORCHIDEE than in SDGVM (respectively −67 and −46 %), and whilst the differences can be partially explained by different model sensitivities to temperature, the major reason for spatial differences between the models is the inclusion of freezing of soil water in ORCHIDEE and the resultant impact on methanogenesis substrate availability in boreal regions. Besides, a sensitivity test performed with ORCHIDEE in which the methanogenesis substrate sensitivity to the precipitations is modified to be more realistic gives a LGM reduction of −36 %. The range of the global LGM decrease is still prone to uncertainty, and here we underline its sensitivity to different process parameteri-zations. Over the course of an idealized D–O warming, the magnitude of the change in wetland CH 4 emissions simulated by the two models at global scale is very similar at around 15 Tg yr −1 , but this is only around 25 % of the ice-core measured changes in [CH 4 ]. The two models do show ...