Articles | Volume 10, issue 11
Geosci. Model Dev., 10, 4005–4033, 2017

Special issue: Paleoclimate Modelling Intercomparison Project phase 4 (PMIP4)...

Special issue: Climate model simulations of the last millennium

Geosci. Model Dev., 10, 4005–4033, 2017

Model experiment description paper 07 Nov 2017

Model experiment description paper | 07 Nov 2017

The PMIP4 contribution to CMIP6 – Part 3: The last millennium, scientific objective, and experimental design for the PMIP4 past1000 simulations

Johann H. Jungclaus1, Edouard Bard2, Mélanie Baroni2, Pascale Braconnot3, Jian Cao4, Louise P. Chini5, Tania Egorova6,7, Michael Evans8, J. Fidel González-Rouco9, Hugues Goosse10, George C. Hurtt5, Fortunat Joos11, Jed O. Kaplan12, Myriam Khodri13, Kees Klein Goldewijk14,15, Natalie Krivova16, Allegra N. LeGrande17, Stephan J. Lorenz1, Jürg Luterbacher18,19, Wenmin Man20, Amanda C. Maycock21, Malte Meinshausen22,23, Anders Moberg24, Raimund Muscheler25, Christoph Nehrbass-Ahles11, Bette I. Otto-Bliesner26, Steven J. Phipps27, Julia Pongratz1, Eugene Rozanov6,7, Gavin A. Schmidt17, Hauke Schmidt1, Werner Schmutz6, Andrew Schurer28, Alexander I. Shapiro16, Michael Sigl29,30, Jason E. Smerdon31, Sami K. Solanki16, Claudia Timmreck1, Matthew Toohey32, Ilya G. Usoskin33, Sebastian Wagner34, Chi-Ju Wu16, Kok Leng Yeo16, Davide Zanchettin35, Qiong Zhang24, and Eduardo Zorita34 Johann H. Jungclaus et al.
  • 1Max Planck Institut für Meteorologie, Hamburg, Germany
  • 2CEREGE, Aix-Marseille University, CNRS, IRD, College de France, Technopole de l'Arbois, 13545 Aix-en-Provence, France
  • 3Laboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA – CNRS-UVSQ, Université Paris-Saclay, 91191 Gif-sur-Yvette, France
  • 4Earth System Modeling Center, Nanjing University of Information Science and Technology, Nanjing 210044, China
  • 5Department of Geographical Sciences, University of Maryland, College Park, MD 20742, USA
  • 6Physikalisch-Meteorologisches Observatorium Davos and World Radiation Center (PMOD/WRC), Davos, Switzerland
  • 7Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland
  • 8Dept. of Geology and Earth System Science Interdisciplinary Center, University of Maryland, College Park, MD 20742, USA
  • 9Dept. of Astrophysics and Atmospheric Sciences, IGEO (UCM-CSIC), Universidad Complutense de Madrid, 28040 Madrid, Spain
  • 10ELI/TECLIM, Université Catholique de Louvain, Louvain-la-Neuve, Belgium
  • 11Climate and Environmental Physics, Physics Institute and Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
  • 12Institute of Earth Surface Dynamics, University of Lausanne, Lausanne, Switzerland
  • 13Laboratoire d'Océanographie et du Climate, Sorbonne Universités, UPMC Université Paris 06, IPSL, UMR CNRS/IRD/MNHN, 75005 Paris, France
  • 14Copernicus Institute of Sustainable Development, Utrecht University, Utrecht, the Netherlands
  • 15PBL Netherlands Environmental Assessment Agency, The Hague/Bilthoven, the Netherlands
  • 16Max-Planck-Institut für Sonnensystemforschung, Göttingen, Germany
  • 17NASA Goddard Institute for Space Studies, 2880 Broadway, New York, USA
  • 18Department of Geography, Climatology, Climate Dynamics and Climate Change, Justus Liebig University Giessen, Giessen, Germany
  • 19Centre for International Development and Environmental Research, Justus Liebig University Giessen, Giessen, Germany
  • 20LASG Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
  • 21School of Earth and Environment, University of Leeds, Leeds, UK
  • 22Australian-German Climate & Energy College, the University of Melbourne, Australia
  • 23Potsdam Institute for Climate Impact Research, Potsdam, Germany
  • 24Department of Physical Geography and Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden
  • 25Department of Geology, Lund University, Lund, Sweden
  • 26National Center for Atmospheric Research, Boulder, Colorado 80305, USA
  • 27Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia
  • 28GeoSciences, University of Edinburgh, Edinburgh, UK
  • 29Laboratory of Environmental Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
  • 30Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland
  • 31Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY, USA
  • 32GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
  • 33Space Climate Research Group and Sodankylä Geophysical Observatory, University of Oulu, Oulu, Finland
  • 34Institute for Coastal Research, Helmholtz-Zentrum Geesthacht, Geesthacht, Germany
  • 35Department of Environmental Sciences, Informatics and Statistics, University of Venice, Mestre, Italy

Abstract. The pre-industrial millennium is among the periods selected by the Paleoclimate Model Intercomparison Project (PMIP) for experiments contributing to the sixth phase of the Coupled Model Intercomparison Project (CMIP6) and the fourth phase of the PMIP (PMIP4). The past1000 transient simulations serve to investigate the response to (mainly) natural forcing under background conditions not too different from today, and to discriminate between forced and internally generated variability on interannual to centennial timescales. This paper describes the motivation and the experimental set-ups for the PMIP4-CMIP6 past1000 simulations, and discusses the forcing agents orbital, solar, volcanic, and land use/land cover changes, and variations in greenhouse gas concentrations. The past1000 simulations covering the pre-industrial millennium from 850 Common Era (CE) to 1849 CE have to be complemented by historical simulations (1850 to 2014 CE) following the CMIP6 protocol. The external forcings for the past1000 experiments have been adapted to provide a seamless transition across these time periods. Protocols for the past1000 simulations have been divided into three tiers. A default forcing data set has been defined for the Tier 1 (the CMIP6 past1000) experiment. However, the PMIP community has maintained the flexibility to conduct coordinated sensitivity experiments to explore uncertainty in forcing reconstructions as well as parameter uncertainty in dedicated Tier 2 simulations. Additional experiments (Tier 3) are defined to foster collaborative model experiments focusing on the early instrumental period and to extend the temporal range and the scope of the simulations. This paper outlines current and future research foci and common analyses for collaborative work between the PMIP and the observational communities (reconstructions, instrumental data).

Short summary
Climate model simulations covering the last millennium provide context for the evolution of the modern climate and for the expected changes during the coming centuries. They can help identify plausible mechanisms underlying palaeoclimatic reconstructions. Here, we describe the forcing boundary conditions and the experimental protocol for simulations covering the pre-industrial millennium. We describe the PMIP4 past1000 simulations as contributions to CMIP6 and additional sensitivity experiments.