Palaeoclimate constraints on the impact of 2 °C anthropogenic warming and beyond

• Published in: Nature Geoscience
• Main Authors: Fischer, Hubertus, Meissner, Katrin, J., Mix, Alan, C., Abram, Nerilie, Austermann, Jacqueline, Brovkin, Victor, Capron, Emilie, Colombaroli, Daniel, Daniau, Anne, Dyez, Kelsey, Felis, Thomas, Finkelstein, Sarah, Jaccard, Samuel, Mcclymont, Erin, Rovere, Alessio, Sutter, Johannes, Wolff, Eric, Affolter, Stéphane, Bakker, Pepijn, Ballesteros-Cánovas, Juan Antonio, Barbante, Carlo, Caley, Thibaut, Carlson, Anders, E., Churakova, Olga, Cortese, Giuseppe, Cumming, Brian, Davis, Basil, A.S., de Vernal, Anne, Emile-Geay, Julien, Fritz, Sherilyn, C., Gierz, Paul, Gottschalk, Julia, Holloway, Max, Joos, Fortunat, Kucera, Michal, Loutre, Marie-France, Lunt, Daniel, Marcisz, Katarzyna, Marlon, Jennifer, Martinez, Matias, Masson-Delmotte, Valérie, Nehrbass-Ahles, Christoph, Otto-Bliesner, Bette, Raible, Christoph, Risebrobakken, Bjørg, Sánchez Goñi, María, Arrigo, Jennifer Saleem, Sarnthein, Michael, Sjolte, Jesper, Stocker, Thomas, Velasquez Alvárez, Patricio, Tinner, Willy, Valdes, Paul, Vogel, Hendrik, Wanner, Heinz, Yan, Qing, Yu, Zicheng, Ziegler, Martin, Zhou, Liping
• Other Authors: Climate and Environmental Physics Bern (CEP), Physikalisches Institut Bern, Universität Bern / University of Bern (UNIBE)-Universität Bern / University of Bern (UNIBE), Oeschger Centre for Climate Change Research (OCCR), Universität Bern / University of Bern (UNIBE), Climate Change Research Centre Sydney (CCRC), University of New South Wales Sydney (UNSW), College of Earth, Ocean and Atmospheric Sciences Corvallis (CEOAS), Oregon State University (OSU), Australian National University (ANU), Bullard Laboratories, University of Cambridge UK (CAM), Max Planck Institute for Meteorology (MPI-M), Max-Planck-Gesellschaft, British Antarctic Survey (BAS), Natural Environment Research Council (NERC), 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), Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Lamont-Doherty Earth Observatory (LDEO), Columbia University New York, Center for Marine Environmental Sciences Bremen (MARUM), Universität Bremen, University of Toronto, Department of Geography (UNIVERSITé DE DURHAM), Durham University, Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung = Alfred Wegener Institute for Polar and Marine Research = Institut Alfred-Wegener pour la recherche polaire et marine (AWI), Helmholtz-Gemeinschaft = Helmholtz Association, Université de Genève = University of Geneva (UNIGE), Institute for the Dynamics of Environmental Processes-CNR, University of Ca’ Foscari Venice, Italy, GNS Science Lower Hutt, GNS Science, Queen's University Kingston, Canada, Institute of Earth Surface Dynamics Lausanne, Université de Lausanne = University of Lausanne (UNIL), Centre de recherche sur la dynamique du système Terre (GEOTOP), École Polytechnique de Montréal (EPM)-McGill University = Université McGill Montréal, Canada -Université de Montréal (UdeM)-Université du Québec en Abitibi-Témiscamingue (UQAT)-Université du Québec à Rimouski (UQAR)-Concordia University Montreal -Université du Québec à Montréal = University of Québec in Montréal (UQAM), University of Southern California (USC), University of Nebraska–Lincoln, University of Nebraska System, PAGES International Project Office, School of Geographical Sciences Bristol, University of Bristol Bristol
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2018
• Subjects: [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology; Antarc*; Antarctic; Greenland
• Online Access: https://cea.hal.science/cea-01883055; https://cea.hal.science/cea-01883055/document; https://cea.hal.science/cea-01883055/file/Fis.pdf; https://doi.org/10.1038/s41561-018-0146-0

International audience Over the past 3.5 million years, there have been several intervals when climate conditions were warmer than during the pre-industrial Holocene. Although past intervals of warming were forced differently than future anthropogenic change, such periods can provide insights into potential future climate impacts and ecosystem feedbacks, especially over centennial-to-millennial timescales that are often not covered by climate model simulations. Our observation-based synthesis of the understanding of past intervals with temperatures within the range of projected future warming suggests that there is a low risk of runaway greenhouse gas feedbacks for global warming of no more than 2 °C. However, substantial regional environmental impacts can occur. A global average warming of 1–2 °C with strong polar amplification has, in the past, been accompanied by significant shifts in climate zones and the spatial distribution of land and ocean ecosystems. Sustained warming at this level has also led to substantial reductions of the Greenland and Antarctic ice sheets, with sea-level increases of at least several metres on millennial timescales. Comparison of palaeo observations with climate model results suggests that, due to the lack of certain feedback processes, model-based climate projections may underestimate long-term warming in response to future radiative forcing by as much as a factor of two, and thus may also underestimate centennial-to-millennial-scale sea-level rise.