CPD Climate of the Past Discussions CPD Clim. Past Discuss. 1814-9359 Göttingen, Germany 10.5194/cp-2018-106 The penultimate deglaciation: protocol for PMIP4 transient numerical simulations between 140 and 127 ka Menviel Laurie https://orcid.org/0000-0002-5068-1591 1 2 22 Capron Emilie 3 4 22 Govin Aline https://orcid.org/0000-0001-8512-5571 5 Dutton Andrea https://orcid.org/0000-0002-3836-119X 6 Tarasov Lev 7 Abe-Ouchi Ayako https://orcid.org/0000-0003-1745-5952 8 Drysdale Russell https://orcid.org/0000-0001-7867-031X 9 10 Gibbard Philip 11 Gregoire Lauren https://orcid.org/0000-0003-0258-7282 12 He Feng https://orcid.org/0000-0002-3355-6406 13 Ivanovic Ruza https://orcid.org/0000-0002-7805-6018 12 Kageyama Masa 5 Kawamura Kenji https://orcid.org/0000-0003-1163-700X 14 15 16 Landais Amaelle 5 Otto-Bliesner Bette L. https://orcid.org/0000-0003-1911-1598 17 Oyabu Ikumi https://orcid.org/0000-0001-8017-1085 14 Tzedakis Polychronis https://orcid.org/0000-0001-6072-1166 18 Wolff Eric https://orcid.org/0000-0002-5914-8531 19 Zhang Xu 20 21 Climate Change Research Center, PANGEA, ARC Centre of Excellence in Climate System Science, the University of New South Wales, Sydney, Australia Department of Earth and Planetary Sciences, Macquarie University, Sydney, NSW 2109, Australia Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, Copenhagen, 2900, Denmark British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 0ET, UK Laboratoire des Sciences du Climat et de l'Environnement (LSCE), Institut Pierre Simon Laplace (IPSL), CEA-CNRS-UVSQ, Université Paris-Saclay, Gif-Sur-Yvette, 91190, France Department of Geological Sciences, University of Florida, P.O. Box 112120, Gainesville, FL 32611, USA Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St John's, Canada Atmosphere and Ocean Research Institute, The University of Tokyo, Tokyo, Japan School of Geography, The University of Melbourne, Melbourne, Australia Laboratoire EDYTEM UMR CNRS 5204, Université Savoie Mont Blanc, 73376 Le Bourget du Lac, France Scott Polar Research Institute, University of Cambridge, Cambridge, CB2 1ER, UK School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UK Center for Climatic Research, Nelson Institute for Environmental Studies, University of Wisconsin-Madison, Madison, WI 53706, USA National Institute of Polar Research, Research Organizations of Information and Systems, 10-3 Midori-cho, Tachikawa, Tokyo 190-8518, Japan Department of Polar Science, Graduate University for Advanced Studies (SOKENDAI), 10-3 Midori-cho, Tachikawa, Tokyo 190-8518, Japan Institute of Biogeosciences, Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushima-cho, Yokosuka 237-0061, Japan Climate and Global Dynamics Laboratory, National Center for Atmospheric Research (NCAR), Boulder, CO 80305, USA Environmental Change Research Centre, Department of Geography, University College London, London, UK Department of Earth Sciences, University of Cambridge, Cambridge, CB2 3EQ, UK Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, 27570 Bremerhaven, Germany Key Laboratory of Western China's Environmental Systems (Ministry of Education), College of Earth and Environmental Sciences, Lanzhou University, Lanzhou, 730000, China These authors contributed equally to this work. 05 09 2018 2018 1 53 Copyright: © 2018 Laurie Menviel et al. 2018 This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/ This article is available from https://cp.copernicus.org/preprints/cp-2018-106/ The full text article is available as a PDF file from https://cp.copernicus.org/preprints/cp-2018-106/cp-2018-106.pdf

<p>The penultimate deglaciation (~&thinsp;138&ndash;128 thousand years before present, hereafter ka) is the transition from the penultimate glacial maximum to the Last Interglacial (LIG, ~&thinsp;129&ndash;116&thinsp;ka). The LIG stands out as one of the warmest interglacials of the last 800&thinsp;ka, with high-latitude temperature warmer than today and global sea level likely higher by at least 6 meters. The LIG therefore receives ever-growing attention, in particular to identify mechanisms and feedbacks responsible for such regional warmth that is comparable to that expected before 2100. Considering the transient nature of the Earth system, the LIG climate and ice-sheets evolution were certainly influenced by the changes occurring during the penultimate deglaciation. It is thus important to investigate the climate and environmental response to the large changes in boundary conditions (i.e. orbital configuration, atmospheric greenhouse gas concentrations, ice sheet geometry) occurring during this time interval.</p> <p> A deglaciation working group has recently been set up as part of the Paleoclimate Modelling Intercomparison Project (PMIP) phase 4, with a protocol to perform transient simulations of the last deglaciation (19&ndash;11&thinsp;ka). Similar to the last deglaciation, the disintegration of continental ice-sheets during the penultimate deglaciation led to significant changes in the oceanic circulation during Heinrich Stadial 11 (~&thinsp;136&ndash;129&thinsp;ka). However, the two deglaciations bear significant differences in magnitude and temporal evolution of climate and environmental changes. </p> <p>Here, as part of the PAGES-PMIP working group on Quaternary Interglacials, we propose a protocol to perform transient simulations of the penultimate deglaciation to complement the PMIP4 effort. This design includes time-varying changes in orbital forcing, greenhouse gas concentrations, continental ice-sheets as well as freshwater input from the disintegration of continental ice-sheets. This experiment is designed to assess the coupled response of the climate system to all forcings. Additional sensitivity experiments are proposed to evaluate the response to each forcing. Finally, a selection of paleo records representing different parts of the climate system is presented, providing an appropriate benchmark for upcoming model-data comparisons across the penultimate deglaciation.</p>