The PMIP4 contribution to CMIP6 – Part 2: Two interglacials, scientific objective and experimental design for Holocene and Last Interglacial simulations Bette Otto-Bliesner, Pascale Braconnot, Sandy Harrison, Daniel Lunt, Ayako Abe-Ouchi, Samuel Albani, Patrick Bartlein, Emilie Capron, Anders Carlson, Andrea Dutton, et al. To cite this version: Bette Otto-Bliesner, Pascale Braconnot, Sandy Harrison, Daniel Lunt, Ayako Abe-Ouchi, et al.. The PMIP4 contribution to CMIP6 – Part 2: Two interglacials, scientific objective and experimental design for Holocene and Last Interglacial simulations. Geoscientific Model Development, European Geosciences Union, 2017, 10 (11), pp.3979-4003. 10.5194/gmd-10-3979-2017. hal-02181006 HAL Id: hal-02181006 https://hal.archives-ouvertes.fr/hal-02181006 Submitted on 11 Jul 2019 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Geosci. Model Dev., 10, 3979–4003, 2017 https://doi.org/10.5194/gmd-10-3979-2017 © Author(s) 2017. This work is distributed under the Creative Commons Attribution 3.0 License. The PMIP4 contribution to CMIP6 – Part 2: Two interglacials, scientific objective and experimental design for Holocene and Last Interglacial simulations Bette L. Otto-Bliesner1, Pascale Braconnot2, Sandy P. Harrison3, Daniel J. Lunt4, Ayako Abe-Ouchi5,6, Samuel Albani7, Patrick J. Bartlein8, Emilie Capron9,10, Anders E. Carlson11, Andrea Dutton12, Hubertus Fischer13, Heiko Goelzer14,15, Aline Govin2, Alan Haywood16, Fortunat Joos13, Allegra N. LeGrande17, William H. Lipscomb18, Gerrit Lohmann19, Natalie Mahowald20, Christoph Nehrbass-Ahles13, Francesco S. R. Pausata21, Jean-Yves Peterschmitt2, Steven J. Phipps22, Hans Renssen23,24, and Qiong Zhang25 1National Center for Atmospheric Research, 1850 Table Mesa Drive, Boulder, CO 80305, USA 2Laboratoire des Sciences du Climat et de l’Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, 91191 Gif-sur-Yvette, France 3Centre for Past Climate Change and School of Archaeology, Geography and Environmental Science (SAGES), University of Reading, Whiteknights, RG6 6AH, Reading, UK 4School of Geographical Sciences, University of Bristol, Bristol, BS8 1SS, UK 5Atmosphere Ocean Research Institute, University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa-shi, Chiba 277-20 8564, Japan 6Japan Agency for Marine-Earth Science and Technology, 3173-25 Showamachi, Kanazawa, Yokohama, Kanagawa, 236-0001, Japan 7Institute for Geophysics and Meteorology, University of Cologne, Cologne, Germany 8Department of Geography, University of Oregon, Eugene, OR 97403-1251, USA 9Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark 10British Antarctic Survey, High Cross Madingley Road, Cambridge CB3 0ET, UK 11College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331, USA 12Department of Geological Sciences, University of Florida, Gainesville, FL 32611, USA 13Climate and Environmental Physics, Physics Institute and Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland 14Institute for Marine and Atmospheric Research Utrecht (IMAU), Utrecht University, Princetonplein 5, 3584 CC Utrecht, the Netherlands 15Laboratoire de Glaciologie, Université Libre de Bruxelles, CP160/03, Av. F. Roosevelt 50, 1050 Brussels, Belgium 16School of Earth and Environment, University of Leeds, Woodhouse Lane, Leeds, West Yorkshire, LS29JT, UK 17NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025, USA 18Group T-3, Fluid Dynamics and Solid Mechanics, Los Alamos National Laboratory, Los Alamos, NM 87545, USA 19Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research Bussestr. 24, 27570 Bremerhaven, Germany 20Earth and Atmospheric Sciences, Cornell University, Ithaca, NY 14850, USA 21Department of Earth and Atmospheric Sciences, University of Quebec in Montreal (UQAM), Montreal, QC, H3C 3P8, Canada 22Institute for Marine and Antarctic Studies, Uinversity of Tasmania, Hobart, Tasmania 7001, Australia 23Department of Earth Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081HV Amsterdam, the Netherlands 24Department of Natural Sciences and Environmental Health, University College of Southeast Norway, 3800 Bø i Telemark, Norway Published by Copernicus Publications on behalf of the European Geosciences Union. 3980 B. L. Otto-Bliesner et al.: PMIP4-CMIP6 interglacial simulations 25Department of Physical Geography, Stockholm University, 10691 Stockholm, Sweden Correspondence to: Bette L. Otto-Bliesner ([email protected]) Received: 3 November 2016 – Discussion started: 28 November 2016 Revised: 20 July 2017 – Accepted: 21 August 2017 – Published: 7 November 2017 Abstract. Two interglacial epochs are included in the suite 2015; Schmidt et al., 2014). The Paleoclimate Modelling In- of Paleoclimate Modeling Intercomparison Project (PMIP4) tercomparison Project (PMIP) has served to coordinate pale- simulations in the Coupled Model Intercomparison Project oclimate experiments and data–model comparisons for sev- (CMIP6). The experimental protocols for simulations of the eral decades (Braconnot et al., 2007a, b, 2012; Joussaume mid-Holocene (midHolocene, 6000 years before present) and and Taylor, 1995; Joussaume et al., 1999), and now spear- the Last Interglacial (lig127k, 127 000 years before present) heads the paleoclimate contribution to the current phase of are described here. These equilibrium simulations are de- the Coupled Model Intercomparison Project (CMIP6, Eyring signed to examine the impact of changes in orbital forcing et al., 2016). at times when atmospheric greenhouse gas levels were sim- This paper is part of a suite of five documenting the ilar to those of the preindustrial period and the continental PMIP4 contributions to CMIP6. Kageyama et al. (2016) configurations were almost identical to modern ones. These provide an overview of the five selected time periods and simulations test our understanding of the interplay between the experiments. More specific information is given in the radiative forcing and atmospheric circulation, and the con- contributions for the last millennium (past1000) by Jung- nections among large-scale and regional climate changes giv- claus et al. (2017), for the last glacial maximum (lgm) by ing rise to phenomena such as land–sea contrast and high- Kageyama et al. (2017), for the mid-Pliocene warm period latitude amplification in temperature changes, and responses (midPliocene-eoi400) by Haywood et al. (2016), and the of the monsoons, as compared to today. They also provide an present paper the mid-Holocene (midHolocene) and the pre- opportunity, through carefully designed additional sensitivity vious interglacial (lig127k). PMIP4 has adopted the CMIP6 experiments, to quantify the strength of atmosphere, ocean, categorization where the highest-priority experiments are cryosphere, and land-surface feedbacks. Sensitivity experi- classified as Tier 1, whereas additional sensitivity experi- ments are proposed to investigate the role of freshwater forc- ments or dedicated studies are Tier 2 or Tier 3. The stan- ing in triggering abrupt climate changes within interglacial dard experiments for the five periods are all ranked Tier 1. epochs. These feedback experiments naturally lead to a fo- Tier 2 and 3 experiments absolutely require the correspond- cus on climate evolution during interglacial periods, which ing Tier 1 experiment for their analysis, so the groups must will be examined through transient experiments. Analyses perform the Tier 1 experiment first. Modeling groups are not of the sensitivity simulations will also focus on interactions obliged to run all PMIP4-CMIP6 experiments. It is manda- between extratropical and tropical circulation, and the rela- tory, however, for all participating groups to run at least one tionship between changes in mean climate state and climate of the experiments that were run in previous phases of PMIP variability on annual to multi-decadal timescales. The com- (i.e., midHolocene or lgm). parative abundance of paleoenvironmental data and of quan- The two experiments described here focus on comparing titative climate reconstructions for the Holocene and Last In- the most recent interglacial epochs and specifically the cur- terglacial make these two epochs ideal candidates for system- rent interglacial (the Holocene) and the previous interglacial atic evaluation of model performance, and such comparisons (the Last Interglacial, LIG) periods (Fig. 1). These two ex- will shed new light on the importance of external feedbacks periments are of interest because they examine the response (e.g., vegetation, dust) and the ability of state-of-the-art mod- of the climate system to relatively simple changes in forcing els to simulate climate changes realistically. compared to present. The main difference in forcing from present was in the latitudinal and seasonal distribution of in- coming solar radiation (insolation) caused by known changes in the Earth’s orbit; greenhouse gas (GHG) concentrations