Comparative carbon cycle dynamics of the present and last interglacial

• Published in: Quaternary Science Reviews
• Main Authors: Brovkin, Victor, Brücher, Tim, Kleinen, Thomas, Zaehle, Sönke, Joos, Fortunat, Roth, Raphaël, Spahni, Renato, Schmitt, Jochen, Fischer, Hubertus, Leuenberger, Markus, Stone, Emma J., Ridgwell, Andy, Chappellaz, Jerome, Kehrwald, Natalie, Blunier, Thomas, Dahl-Jensen, Dorthe
• Other Authors: Max Planck Institute for Meteorology (MPI-M), Max-Planck-Gesellschaft, Biogeochemical Systems Department Jena, Max Planck Institute for Biogeochemistry (MPI-BGC), Max-Planck-Gesellschaft-Max-Planck-Gesellschaft, Climate and Environmental Physics Bern (CEP), Physikalisches Institut Bern, Universität Bern = University of Bern = Université de Berne (UNIBE)-Universität Bern = University of Bern = Université de Berne (UNIBE), University of Bristol Bristol, Université Grenoble Alpes 2016-2019 (UGA 2016-2019 ), Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes 2016-2019 (UGA 2016-2019 )-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes 2016-2019 (UGA 2016-2019 ), Department of Environmental Sciences, Informatics and Statistics Venezia, University of Ca’ Foscari Venice, Italy, Centre for Ice and Climate Copenhagen, Niels Bohr Institute Copenhagen (NBI), Faculty of Science Copenhagen, University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH)-Faculty of Science Copenhagen, University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2016
• Subjects: Carbon cycle; Climate; Models; Interglacials; The Holocene; The Eemian; Peatland; Fire; Coral reef; [SDE]Environmental Sciences; Antarctic; Antarc*; Ice; permafrost
• Online Access: https://insu.hal.science/insu-01352021; https://insu.hal.science/insu-01352021/document; https://insu.hal.science/insu-01352021/file/1-s2.0-S0277379116300300-main.pdf; https://doi.org/10.1016/j.quascirev.2016.01.028

International audience Changes in temperature and carbon dioxide during glacial cycles recorded in Antarctic ice cores are tightly coupled. However, this relationship does not hold for interglacials. While climate cooled towards the end of both the last (Eemian) and present (Holocene) interglacials, CO2 remained stable during the Eemian while rising in the Holocene. We identify and review twelve biogeochemical mechanisms of terrestrial (vegetation dynamics and CO2 fertilization, land use, wildfire, accumulation of peat, changes in permafrost carbon, subaerial volcanic outgassing) and marine origin (changes in sea surface temperature, carbonate compensation to deglaciation and terrestrial biosphere regrowth, shallow-water carbonate sedimentation, changes in the soft tissue pump, and methane hydrates), which potentially may have contributed to the CO2 dynamics during interglacials but which remain not well quantified. We use three Earth System Models (ESMs) of intermediate complexity to compare effects of selected mechanisms on the interglacial CO2 and δ13CO2 changes, focusing on those with substantial potential impacts: namely carbonate sedimentation in shallow waters, peat growth, and (in the case of the Holocene) human land use. A set of specified carbon cycle forcings could qualitatively explain atmospheric CO2 dynamics from 8 ka BP to the pre-industrial. However, when applied to Eemian boundary conditions from 126 to 115 ka BP, the same set of forcings led to disagreement with the observed direction of CO2 changes after 122 ka BP. This failure to simulate late-Eemian CO2 dynamics could be a result of the imposed forcings such as prescribed CaCO3 accumulation and/or an incorrect response of simulated terrestrial carbon to the surface cooling at the end of the interglacial. These experiments also reveal that key natural processes of interglacial CO2 dynamics – shallow water CaCO3 accumulation, peat and permafrost carbon dynamics - are not well represented in the current ESMs. Global-scale modeling of these ...