EGUsphere EGUsphere EGUsphere EGUsphere Copernicus Publications Göttingen, Germany 10.5194/egusphere-2026-1698 TIPMIP-OCEAN experimental protocol phase 1: Tipping dynamics of the AMOC Swingedouw Didier https://orcid.org/0000-0002-0583-0850 1 Jackson Laura 2 Hu Aixue https://orcid.org/0000-0002-1337-287X 3 Romanou Anastasia https://orcid.org/0000-0001-5241-4772 4 Laureanti Nicole C. https://orcid.org/0000-0001-5588-2950 5 6 Weijer Wilbert 7 Loriani Sina https://orcid.org/0000-0001-6660-960X 5 6 Otto-Bliesner Bette https://orcid.org/0000-0003-1911-1598 3 Abe-Ouchi Ayako https://orcid.org/0000-0003-1745-5952 8 Almeida Lucas https://orcid.org/0000-0002-4401-0273 1 Bellucci Alessio 9 Börner Reyk https://orcid.org/0000-0003-4593-7721 10 Danabasoglu Gokhan https://orcid.org/0000-0003-4676-2732 3 Dennis Donovan P. https://orcid.org/0000-0002-5423-7703 5 Devilliers Marion https://orcid.org/0000-0002-3929-2747 11 Drijfhout Sybren 12 Donges Jonathan https://orcid.org/0000-0001-5233-7703 5 Fröb Friederike https://orcid.org/0000-0002-2516-1682 13 Frölicher Thomas L. 14 15 Gastineau Guillaume 16 Goelzer Heiko https://orcid.org/0000-0002-5878-9599 17 Guo Chuncheng 11 Hofmann Urs https://orcid.org/0000-0003-4576-471X 14 15 Höse Anna 18 Jones Colin https://orcid.org/0000-0002-7221-8127 19 Koenigk Torben https://orcid.org/0000-0003-2051-743X 20 Klose Ann Kristin https://orcid.org/0000-0003-4043-7357 5 6 Lembo Valerio https://orcid.org/0000-0001-6085-5914 21 Licon-Salaiz Jose https://orcid.org/0000-0002-8733-2256 5 Mankoff Ken https://orcid.org/0000-0001-5453-2019 4 22 Meccia Virna https://orcid.org/0000-0001-6905-2747 9 Melnikova Irina https://orcid.org/0000-0002-4352-191X 23 Mehling Oliver https://orcid.org/0000-0002-4338-218X 24 Menviel Laurie https://orcid.org/0000-0002-5068-1591 25 Mignot Juliette https://orcid.org/0000-0002-4894-898X 16 Robson Jon I. https://orcid.org/0000-0002-3467-018X 26 Schmidt Gavin A. https://orcid.org/0000-0002-2258-0486 4 Smith Robin https://orcid.org/0000-0001-7479-7778 26 Sun Yuchen https://orcid.org/0000-0002-2449-8718 27 Trombini Irene https://orcid.org/0000-0002-7070-7162 28 9 Willeit Matteo https://orcid.org/0000-0003-3998-6404 5 Wood Richard https://orcid.org/0000-0002-3960-9513 2 Wu Fanghua https://orcid.org/0000-0003-1066-6538 29 Zhaohui Lin https://orcid.org/0000-0003-1376-3106 30 Winkelmann Ricarda https://orcid.org/0000-0003-1248-3217 5 6 EPOC - Univ. Bordeaux, CNRS, Bordeaux INP, UMR 5805, F-33600 Pessac, France Met Office, Exeter, UK US National Science Foundation National Center for Atmospheric Research, Boulder, CO, USA NASA Goddard Institute for Space Studies, New York, NY, USA Potsdam Institute for Climate Impact Research, Potsdam, BB, Germany Max Planck Institute for Geoanthropology, Jena, Germany Los Alamos National Laboratory, Los Alamos, NM, USA Atmosphere and Ocean Research Institute, The University of Tokyo, Tokyo, Japan Institute for Atmospheric Sciences and Climate, National Research Council of Italy, Bologna, Italy Institute for Marine and Atmospheric research Utrecht, Department of Physics, Utrecht University, Utrecht, The Netherlands Danish Meteorological Institute (DMI), Copenhagen, Denmark Royal Netherlands Meteorological Institute (KNMI), de Bilt, the Netherlands Geophysical Institute, University of Bergen, and Bjerknes Centre for Climate Research, Bergen, Norway Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland Oeschger Center for Climate Change Research, University of Bern, Bern, Switzerland Sorbonne Universités (SU/CNRS/IRD/MNHN), IPSL Laboratory, Institut Pierre Simon Laplace (IPSL), Paris, France NORCE Research, Bjerknes Centre for Climate Research, Bergen, Norway Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), Helmholtz Association, Germany National Centre for Atmospheric Science, University of Leeds, Leeds, UK Swedish Meteorological and Hydrological Institute, Norrköping, Sweden Institute for Atmospheric Sciences and Climate, National Research Council of Italy, Italy Geological Survey of Denmark and Greenland (GEUS) Earth System Division, National Institute for Environmental Studies (NIES), Tsukuba, Japan Institute for Marine and Atmospheric Research, Utrecht University, Utrecht, The Netherlands Climate Change Research Centre, Australian Centre of Excellence in Antarctic Science, University of New South Wales, Sydney, Australia National Centre for Atmospheric Science, University of Reading, Reading, UK, RG6 6ES Paleoclimate Dynamics, Alfred Wegener Institute Helmholtz Center for Polar and Marine Research, Bremerhaven, Germany Department of Physics and Astronomy, University of Bologna, Bologna, Italy State Key Laboratory of Severe Weather Meteorological Science and Technology, Earth System Modeling and Prediction Centre, Meteorological Administration, Beijing 100081, China International Center for Climate and Environment Sciences, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China 08 04 2026 2026 1 36 Copyright: © 2026 Didier Swingedouw et al. 2026 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://egusphere.copernicus.org/preprints/2026/egusphere-2026-1698/ The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-1698/egusphere-2026-1698.pdf

This paper describes the experimental protocol for a set of coordinated simulations involving oceanic surface freshwater flux perturbations, conducted as part of the international Tipping Points Modelling Intercomparison Project (TIPMIP). These simulations constitute the first phase of the TIPMIP-OCEAN domain. We propose this protocol for inclusion in the Coupled Model Intercomparison Project Phase 7 (CMIP7), although it can also be implemented within CMIP6+ or other types of coupled or ocean standalone models. This initial phase focuses primarily on the dynamics of the North Atlantic Ocean, particularly the Atlantic Meridional Overturning Circulation (AMOC). The different experiments are designed to (i) evaluate the impacts of a potential major AMOC weakening under a 2 &deg;C global warming scenario, (ii) assess the sensitivity of the AMOC to combined global warming and freshwater forcing, (iii) investigate the potential recovery of the AMOC following the reversal of forcings, and (iv) compare past AMOC variations with available climate observations and reconstructions. Four categories of experiments are included. Experiment group A examines the effect of freshwater release around Greenland under ramp-up, stabilization, and ramp-down scenarios in both CO<sub>2</sub> emissions and freshwater input. Experiment group B complements this idealized set by using historical climate simulations and projections for 1850&ndash;2100, incorporating realistic estimates of Greenland Ice Sheet melt based on observations for the historical period and ice-sheet model projections for the future. Experiment group C extends the existing North Atlantic Hosing Model Intercomparison Project (NAHosMIP) by applying large freshwater perturbations to both control and 2 &deg;C-warming simulations to assess how global warming influences AMOC reversibility. Finally, experiment group D imposes freshwater inputs, consistent with those inferred for the 8.2 kyr before present event, under pre-industrial conditions, in order to constrain model sensitivity to freshwater forcing using paleoclimate reconstructions. Together, these coordinated experiments will allow systematic evaluation of how different climate models respond to identical freshwater perturbations&mdash;an essential step toward better understanding the wide inter-model spread in North Atlantic dynamics and projected future AMOC changes.