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1. A global database of Holocene paleotemperature records

Author

Marcela Sandra Tonello, Vincent Montade, Walter Finsinger, Karen J. Taylor, Manuel Chevalier, Isabelle Larocque-Tobler, Philipp Sommer, Nicholas P. McKay, Mateusz Płóciennik, Snezhana Zhilich, David F. Porinchu, Andrei Andreev, Markus Heinrichs, Tomi P. Luoto, Elena A. Ilyashuk, Anson W. Mackay, Deborah Khider, Stephen J. Roberts, Cody C. Routson, Les C. Cwynar, Samuel L Jaccard, Naomi Holmes, Kira Rehfeld, Aaron P. Potito, Emma J. Pearson, Steve Juggins, Anais Orsi, Louise C. Foster, Angela Self, Sakari Salonen, Basil A. S. Davis, Boris K. Biskaborn, Christoph Dätwyler, Sebastien Bertrand, Anne de Vernal, Jeannine Marie St-Jacques, Angelica Feurdean, Janet M. Wilmshurst, Lukas Jonkers, Heikki Seppä, Stephen J. Brooks, Elizabeth K. Thomas, Sonja Hausmann, Peter G. Langdon, Steven B. Malevich, Larisa Nazarova, Shyhrete Shala, Enikö Magyari, Matthew Peros, Scott A. Reinemann, Krystyna M. Saunders, Elena Novenko, Barbara Stenni, Yarrow Axford, Liudmila Syrykh, Julien Emile-Geay, Nicolas Rolland, Bryan G. Mark, Jianyong Li, Andria Dawson, Mathew Fox, André F. Lotter, Jessica E. Tierney, Oliver Heiri, Stefan Engels, Ian R. Walker, Andrew P. Rees, Pol Tarrats, Valerie van den Bos, Konrad Gajewski, Brian M. Chase, Eugene R. Wahl, Martin Grosjean, Boris P. Ilyashuk, Thomas Brussel, Mónika Tóth, Enlou Zhang, Darrell S. Kaufman, Olivier Cartapanis, Magaly Caniupán, Julieta Massaferro, Reinhard Pienitz, John M. Fegyveresi, Manuel Bringué, Carrie Morrill, Gaute Velle, M. P. Erb, Marie Claude Fortin, Petr Pařil, Karin A. Koinig, Richard S. Vachula, Paola Moffa-Sanchez, Jeremiah Marsicek, Northern Arizona University [Flagstaff], Institute of Earth Surface Dynamics [Lausanne], Université de Lausanne (UNIL), Utrecht University Palaeoecology, Laboratory of Palaeobotany and Palynology (UTRECHT UNIVERSITY), Utrecht University [Utrecht], Oeschger Centre for Climate Change Research (OCCR), University of Bern, University of Arizona, Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA), Institut des Sciences de l'Evolution de Montpellier (UMR ISEM), École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Montpellier (UM)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre National de la Recherche Scientifique (CNRS)-Institut de recherche pour le développement [IRD] : UR226, Mount Royal University, Centre de recherche sur la dynamique du système Terre (GEOTOP), Université de Montréal (UdeM)-McGill University = Université McGill [Montréal, Canada]-École Polytechnique de Montréal (EPM)-Concordia University [Montreal]-Université du Québec à Rimouski (UQAR)-Université du Québec à Montréal = University of Québec in Montréal (UQAM)-Université du Québec en Abitibi-Témiscamingue (UQAT), Center for Marine Environmental Sciences [Bremen] (MARUM), Universität Bremen, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institute of Environmental Physics [Heidelberg] (IUP), Universität Heidelberg [Heidelberg], Programme CIT, Ligue Nationale Contre le Cancer, Snecma Propulsion Solide (SPS), SAFRAN Group, University of Southern California (USC), Senckenberg biodiversität und klima forschungszentrum (BIK-F), Forschungsinstitut Senckenberg (SGN), Université d'Ottawa [Ontario] (uOttawa), Faculty of Biological and Environmental Sciences [Helsinki], University of Helsinki, Department of Environmental and Landscape Geography, Eötvös Loránd University (ELTE), MTA-MTM-ELTE Research Group for Paleontology, Eötvös Loránd University (ELTE)-Hungarian Academy of Sciences (MTA), GINOP Sustainable Ecosystem Research Group, MTA Centre for Ecological Research [Tihany], Hungarian Academy of Sciences (MTA)-Hungarian Academy of Sciences (MTA), Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires] (CONICET), Centre d'Etudes Nordiques (CEN), Université Laval [Québec] (ULaval), British Antarctic Survey (BAS), Natural Environment Research Council (NERC), Department of Geosciences and Geography [Helsinki], Falculty of Science [Helsinki], University of Helsinki-University of Helsinki, Departemanto di Scienze Ambientali Informatica e Statistica (DAIS), University of Ca’ Foscari [Venice, Italy], Uni Research Environment, Uni Research Ltd, University of Bath [Bath], Université de Lausanne = University of Lausanne (UNIL), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Montpellier (UM)-Institut de recherche pour le développement [IRD] : UR226-Centre National de la Recherche Scientifique (CNRS), 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), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Universität Heidelberg [Heidelberg] = Heidelberg University, Ligue Nationale Contre le Cancer (LNCC), Helsingin yliopisto = Helsingfors universitet = University of Helsinki, Helsingin yliopisto = Helsingfors universitet = University of Helsinki-Helsingin yliopisto = Helsingfors universitet = University of Helsinki, Faculty of Biological and Environmental Sciences, and Department of Geosciences and Geography

Subjects
Peat, 010504 meteorology & atmospheric sciences, 580 Plants (Botany), computer.software_genre, 01 natural sciences, MILLENNIAL-SCALE CHANGES, Proxy (climate), purl.org/becyt/ford/1 [https], purl.org/becyt/ford/1.5 [https], INTERTROPICAL CONVERGENCE ZONE, HOLOCENE, 910 Geography & travel, lcsh:Science, Holocene, LAKE VUOLEP-NJAKAJAURE, geography.geographical_feature_category, Database, EASTERN TIBETAN PLATEAU, [SDV.BIBS]Life Sciences [q-bio]/Quantitative Methods [q-bio.QM], Computer Science Applications, LATE-QUATERNARY VEGETATION, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, SEA-SURFACE TEMPERATURE, PROXIES, Statistics, Probability and Uncertainty, geog, Geology, Information Systems, Statistics and Probability, 1171 Geosciences, 010506 paleontology, NORTHERN NORTH-ATLANTIC, DATABASE, PALEOTEMPERATURE, [SDE.MCG]Environmental Sciences/Global Changes, education, Library and Information Sciences, Education, Paleoclimatology, SOUTH CHINA SEA, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Southern Hemisphere, 1172 Environmental sciences, POLLEN-BASED RECONSTRUCTION, 550 Earth sciences & geology, 0105 earth and related environmental sciences, geography, [INFO.INFO-DB]Computer Science [cs]/Databases [cs.DB], Intertropical Convergence Zone, Glacier, 15. Life on land, WESTERN EQUATORIAL PACIFIC, Sea surface temperature, 13. Climate action, Settore GEO/08 - Geochimica e Vulcanologia, Earth and Environmental Sciences, lcsh:Q, computer
Abstract

A comprehensive database of paleoclimate records is needed to place recent warming into the longer-term context of natural climate variability. We present a global compilation of quality-controlled, published, temperature-sensitive proxy records extending back 12,000 years through the Holocene. Data were compiled from 679 sites where time series cover at least 4000 years, are resolved at sub-millennial scale (median spacing of 400 years or finer) and have at least one age control point every 3000 years, with cut-off values slackened in data-sparse regions. The data derive from lake sediment (51%), marine sediment (31%), peat (11%), glacier ice (3%), and other natural archives. The database contains 1319 records, including 157 from the Southern Hemisphere. The multi-proxy database comprises paleotemperature time series based on ecological assemblages, as well as biophysical and geochemical indicators that reflect mean annual or seasonal temperatures, as encoded in the database. This database can be used to reconstruct the spatiotemporal evolution of Holocene temperature at global to regional scales, and is publicly available in Linked Paleo Data (LiPD) format. Fil: Kaufman, Darrell. Northern Arizona University.; Estados Unidos Fil: McKay, Nicholas. Northern Arizona University.; Estados Unidos Fil: Routson, Cody. Northern Arizona University.; Estados Unidos Fil: Erb, Michael. Northern Arizona University.; Estados Unidos Fil: Davis, Basil. University Of Lausanne; Suiza Fil: Heiri, Oliver. University Of Basel; Suiza Fil: Jaccard, Samuel. University Of Bern; Suiza Fil: Tierney, Jessica. University of Arizona; Estados Unidos Fil: Dätwyler, Christoph. University Of Bern; Suiza Fil: Axford, Yarrow. Northwestern University; Estados Unidos Fil: Brussel, Thomas. University of Utah; Estados Unidos Fil: Cartapanis, Olivier. University Of Bern; Suiza Fil: Chase, Brian. Universite de Montpellier; Francia Fil: Dawson, Andria. Mount Royal University; Canadá Fil: de Vernal, Anne. Université du Québec a Montreal; Canadá Fil: Engels, Stefan. University of London; Reino Unido Fil: Jonkers, Lukas. University Of Bremen; Alemania Fil: Marsicek, Jeremiah. University of Wisconsin-Madison; Estados Unidos Fil: Moffa Sánchez, Paola. University of Durham; Reino Unido Fil: Morrill, Carrie. University of Colorado; Estados Unidos Fil: Orsi, Anais. Université Paris-Saclay; Francia Fil: Rehfeld, Kira. Heidelberg University; Alemania Fil: Saunders, Krystyna. Australian Nuclear Science And Technology Organisation; Australia Fil: Sommer, Philipp. University Of Lausanne; Suiza Fil: Thomas, Elizabeth. University At Buffalo; Estados Unidos Fil: Tonello, Marcela Sandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina Fil: Tóth, Mónika. Balaton Limnological Institute; Hungría Fil: Vachula, Richard. Brown University; Estados Unidos Fil: Andreev, Andrei. Alfred Wegener Institut Helmholtz Centre for Polar and Marine Research; Alemania Fil: Bertrand, Sebastien. Ghent University; Bélgica Fil: Massaferro, Julieta. Administración de Parques Nacionales. Parque Nacional "Nahuel Huapi"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Published
2020
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2. Spatial contrasts of the Holocene hydroclimate trend between North and East Asia

Author

Paul J. Valdes, Jianyong Li, Yurui Zhang, Hans Renssen, Heikki Seppä, Laboratoire d'Océanographie Physique et Spatiale (LOPS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), University of South-Eastern Norway (USN), University of Helsinki, University of Bristol [Bristol], Northwest A&F Univ, Coll Anim Sci & Technol, Yangling, Shaanxi, Peoples R China, Partenaires INRAE, Institut Pasteur de Shanghai, Académie des Sciences de Chine - Chinese Academy of Sciences (IPS-CAS), Réseau International des Instituts Pasteur (RIIP), French National Research Agency (ANR) [ANR-17-EURE-0015, ANR-10-LABX19], Academy of Finland (GRASS) [316702], Chinese Academy of SciencesChinese Academy of Sciences [Y652001589, Y651031589, XAB20161301], National Natural Science Foundation of ChinaNational Natural Science Foundation of China (NSFC) [NSFC 41801090], ANR-10-LABX-0019,LabexMER,LabexMER Marine Excellence Research: a changing ocean(2010), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Helsingin yliopisto = Helsingfors universitet = University of Helsinki, and Department of Geosciences and Geography

Subjects
1171 Geosciences, 010506 paleontology, Archeology, 010504 meteorology & atmospheric sciences, Orbital forcing, WESTERLIES, Monsoon, 01 natural sciences, Proxy (climate), MECHANISMS, ICE SHEETS, ARID CENTRAL-ASIA, East Asia, TEMPERATURE, Ecology, Evolution, Behavior and Systematics, Holocene, 0105 earth and related environmental sciences, Global and Planetary Change, geography.geographical_feature_category, COMPLEXITY, Geology, Westerlies, 15. Life on land, SUMMER MONSOON, CLIMATE, Geography, [SDV.MP]Life Sciences [q-bio]/Microbiology and Parasitology, 13. Climate action, PRECIPITATION, Physical geography, Ice sheet, Atmospheric humidity, SYSTEM MODEL
Abstract

The hydroclimate over Asia has undergone important changes over the Holocene with spatially asynchronous trends. Proxy-based evidence shows that North Asia was markedly drier than today during the early Holocene, whereas East Asia, influenced by the monsoon system, was substantially wetter. Yet, the causes behind this contrast are only partly understood due to a lack of overview of the most important factors. Here we explore a combination of climate proxies and multiple climate-model simulations to show that the strong contrast between the dry North Asia and wet (mid-latitude) East Asia is explained by a complex interplay between the effects of remnant ice sheets and orbital forcing. In North Asia, the climate was dry due a weakening of the westerlies and reduced atmospheric humidity, linked to the ice sheets in North America and Fennoscandia. In East Asia, contrarily, the orbitally-forced enhancement of the summer monsoons caused the early Holocene climate to be much wetter than during the presentday. These results indicate that the sensitivity of the hydroclimate in Asia to climate-forcings is spatially different, with important implications for the interpretation of past and future climate changes in this region. (C) 2019 Elsevier Ltd. All rights reserved.

Published
2020
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3. The global hydroclimate response during the Younger Dryas event

Author

Hugues Goosse, Didier M. Roche, Heikki Seppä, Hans Renssen, Vrije Universiteit Amsterdam [Amsterdam] (VU), Institut d'Astronomie et de Géophysique Georges Lemaître (UCL-ASTR), Université Catholique de Louvain = Catholic University of Louvain (UCL), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Modélisation du climat (CLIM), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Department of Geosciences and Geography [Helsinki], Falculty of Science [Helsinki], University of Helsinki-University of Helsinki, Earth and Climate, UCL - SST/ELI/ELIC - Earth & Climate, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Helsingin yliopisto = Helsingfors universitet = University of Helsinki-Helsingin yliopisto = Helsingfors universitet = University of Helsinki

Subjects
Intertropical convergence zone, North Atlantic Ocean, Archeology, Atmospheric chemistry, Younger Dryas, 010504 meteorology & atmospheric sciences, Atlantic meridional overturning circulations, Climate change, Oceanography, 010502 geochemistry & geophysics, 01 natural sciences, Climate models, Paleoclimate modelling, SDG 14 - Life Below Water, Atmospheric movements, Southern Hemisphere, Ecology, Evolution, Behavior and Systematics, Holocene, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Global and Planetary Change, Intertropical Convergence Zone, Ocean current, Tropics, Northern Hemisphere, Global, Geology, Radiative forcing, Glacial geology, 13. Climate action, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Climatology, Soil moisture, Atmospheric methanes, Melt-water discharges, Atmospheric radiation
Abstract

To analyze the global hydroclimate response during the Younger Dryas cold event, we evaluate climate model results that have been constrained with proxy-based temperatures from the North Atlantic region. We find that both the temperature and the hydroclimate response have a clear global signature. A marked cooling is simulated over the North Atlantic Ocean (more than 5 °C) and the downwind continents (2–4 °C). This response is related to the weakening of the Atlantic meridional overturning circulation under influence of meltwater discharges. The hydroclimate response is most expressed over Eurasia in a belt between 40 and 60°N, and over Northern Africa in the Sahel region. In both areas, a strong decrease in soil moisture is simulated (up to 20% reduction). In contrast, a striking increase in moisture is found over southeastern North America (15% increase), where southerly atmospheric flow brings moist air to the continent. Outside these areas that are clearly affected by the cold North Atlantic Ocean, the responses of temperature and moisture are decoupled, with different causes for these temperature and hydroclimate responses. In the tropics, the hydroclimate response is governed by the southward shift of the intertropical convergence zone (ITCZ) due to the cooling of the North Atlantic Ocean. This causes drier conditions north of the equator and wetter conditions in the Southern Hemisphere tropics. The associated changes in soil moisture are relatively gradual here, taking up to two centuries to complete, suggesting that the impact of the ITCZ shift on the tropical hydroclimate is building up. Our experiment indicates that Southern Hemisphere continents experienced a small cooling (less than 0.5 °C) during the Younger Dryas, caused by the negative radiative forcing associated with reduced atmospheric methane concentrations and enhanced dust levels. In our simulation, the bi-polar seesaw mechanism is relatively weak, so that the associated warming of the South Atlantic Ocean is not overwhelming the reduction in radiative forcing. Our results thus indicate that in the tropics and/or Southern Hemisphere, the cooling is a response to the negative radiative forcing, while the hydroclimatic changes are predominantly resulting from ITCZ variations. Consequently, when interpreting hydroclimatic proxy records from these regions, data should not be compared directly to key records from high latitudes, such as Greenland ice core stable isotope records. © 2018 Elsevier Ltd

Published
2018
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4. Pollen-based quantitative reconstructions of Holocene regional vegetation cover (plant-functional types and land-cover types) in Europe suitable for climate modelling

Author

Małgorzata Latałowa, Thomas Giesecke, Matts Lindbladh, B. van Geel, Marie-José Gaillard, P. van der Knaap, Shinya Sugita, Chris Caseldine, Walter Dörfler, Chantal Leroyer, Jutta Lechterbeck, Mihkel Kangur, Siim Veski, Anneli Poska, Per Lagerås, Laurent Marquer, Anna-Kari Trondman, Ralph Fyfe, Philip Barratt, Florence Mazier, Manfred Rösch, Tiiu Koff, E. Fischer, Tove Hultberg, Thomas Persson, Bent Vad Odgaard, Michelle Leydet, Anna Broström, Petr Kuneš, Heikki Seppä, Harry John Betteley Birks, John Dodson, Anne Birgitte Nielsen, Fraser J.G. Mitchell, Lucia Wick, Laimdota Kalnina, Leif Björkman, Claire L. Twiddle, S. M. Peglar, Rémi David, Anne E. Bjune, Department of Biology and Environmental Science, Géographie de l'environnement (GEODE), Université Toulouse - Jean Jaurès (UT2J)-Centre National de la Recherche Scientifique (CNRS), Institute of Ecology, Tallinn University-Tallinn University, School of Geography, Plymouth University-Plymouth University, Department of Geology, Lund University [Lund], Northern Rivers Institute, School of Geosciences, University of Aberdeen, Queen's University [Belfast] (QUB), Department of Biology and Bjerkness Centre for Climate Research, Uni Research Climate, Uni Research Ltd, Bjerknes Centre for Climate Research (BCCR), Department of Biological Sciences [Bergen] (BIO / UiB), University of Bergen (UiB)-University of Bergen (UiB), Viscum pollenanalys and miljohistoria, Viscum pollenanalys and miljohistoria-Viscum pollenanalys and miljohistoria, Department of Geology, Quaternary Sciences, College of Life and Environmental Sciences, Centre de Recherche en Archéologie, Archéosciences, Histoire (CReAAH), Université de Nantes (UN)-Le Mans Université (UM)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Ministère de la Culture (MC), Institute for Environmental Research, Australian Nuclear Science and Technology Organisation, Institute fur Ur und fruhgeschichte, Department of Paleoecology and landscape Ecology, Department of Palynology and Climate Dynamics, Georg-August-University [Göttingen]-Georg-August-University [Göttingen], Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences (SLU), Faculty of Geography and Earth Sciences [Riga], University of Latvia (LU), Institute of Plant Sciences, Department of Botany, Faculty of Science, Swedish National Heritage Board, Laboratory of Palaeoecology and Archaeology, University of Gdańsk (UG)-University of Gdańsk (UG), State Office for cultural Heritage Baden-Wuerttemberg, Institut méditerranéen de biodiversité et d'écologie marine et continentale (IMBE), Avignon Université (AU)-Aix Marseille Université (AMU)-Institut de recherche pour le développement [IRD] : UMR237-Centre National de la Recherche Scientifique (CNRS), Botany Department, Trinity College Dublin (TCD), Trinity College Dublin, Department of Geoscience [Aarhus], Aarhus University [Aarhus], Department of Physical Geography and Ecosystem Science [Lund], P.O. Box 64, Institute of Geology, Tallinn University of Technology (TTÜ), University of Basel (Unibas), VR 349-2007-8705, Swedish [VR] Research Council, Centre National de la Recherche Scientifique (CNRS)-Université Toulouse - Jean Jaurès (UT2J), Nantes Université (NU)-Ministère de la Culture (MC)-Centre National de la Recherche Scientifique (CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Le Mans Université (UM), Université Toulouse - Jean Jaurès (UT2J), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Le Mans Université (UM)-Université de Rennes (UR)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Université de Nantes - UFR Histoire, Histoire de l'Art et Archéologie (UFR HHAA), Université de Nantes (UN)-Université de Nantes (UN)-Ministère de la Culture (MC), Georg-August-University = Georg-August-Universität Göttingen-Georg-August-University = Georg-August-Universität Göttingen, Charles University [Prague] (CU), Paleoecology and Landscape Ecology (IBED, FNWI), Department of Geosciences and Geography, Université de Nantes - UFR Histoire, Histoire de l'Art et Archéologie (UFR HHAA), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Ministère de la Culture (MC)-Université de Rennes 2 (UR2), and Centre National de la Recherche Scientifique (CNRS)-Institut de recherche pour le développement [IRD] : UMR237-Aix Marseille Université (AMU)-Avignon Université (AU)

Subjects
DYNAMICS, Climate Change, Biodiversity, SOURCE AREA, Land cover, 580 Plants (Botany), medicine.disease_cause, 114 Physical sciences, pollen data, FUTURE, Deforestation, Pollen, medicine, Environmental Chemistry, ALGORITHM, 1172 Environmental sciences, Holocene, ComputingMilieux_MISCELLANEOUS, General Environmental Science, Global and Planetary Change, Ecology, REVEALS model, OPENNESS, Plant Dispersal, QUATERNARY PALYNOLOGICAL DATABASE, SOUTHERN SWEDEN, Vegetation, [SHS.GEO]Humanities and Social Sciences/Geography, Models, Theoretical, 15. Life on land, Evergreen, quantitative past land cover, TERRESTRIAL ECOSYSTEMS, Europe, Deciduous, Matematikk og naturvitenskap: 400 [VDP], Mathematics and natural scienses: 400 [VDP], 13. Climate action, 1181 Ecology, evolutionary biology, plant-functional types, REVEALS-MODEL, CARBON-CYCLE
Abstract

A contribution to the PAGES Focus 4 Land Use and Cover Theme ABSTRACT: We present quantitative reconstructions of regional vegetation cover in north western Europe western Europe north of the Alps and eastern Europe for five time windows in the Holocene [around 6k 3k 0.5k 0.2k and 0.05k calendar years before present (bp)] at a 1° × 1° spatial scale with the objective of producing vegetation descriptions suitable for climate modelling. The REVEALS model was applied on 636 pollen records from lakes and bogs to reconstruct the past cover of 25 plant taxa grouped into 10 plant functional types and three land cover types [evergreen trees summer green (deciduous) trees and open land]. The model corrects for some of the biases in pollen percentages by using pollen productivity estimates and fall speeds of pollen and by applying simple but robust models of pollen dispersal and deposition. The emerging patterns of tree migration and deforestation between 6k bp and modern time in the REVEALS estimates agree with our general understanding of the vegetation history of Europe based on pollen percentages. However the degree of anthropogenic deforestation (i.e. cover of cultivated and grazing land) at 3k 0.5k and 0.2k bp is significantly higher than deduced from pollen percentages. This is also the case at 6k in some parts of Europe in particular Britain and Ireland. Furthermore the relationship between summer green and evergreen trees and between individual tree taxa differs significantly when expressed as pollen percentages or as REVEALS estimates of tree cover. For instance when Pinus is dominant over Picea as pollen percentages Picea is dominant over Pinus as REVEALS estimates. These differences play a major role in the reconstruction of European landscapes and for the study of land cover–climate interactions biodiversity and human resources.

Published
2015
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5. Validation of climate model-inferred regional temperature change for late-glacial Europe

Author

Enikö Magyari, Castor Muñoz Sobrino, Saskia Kuiper, Emiliya P. Kirilova, H. John B. Birks, Oliver Heiri, Heikki Seppä, Jenny E. Watson, Hans Renssen, André F. Lotter, Wim Z. Hoek, Alan Bedford, Mónika Tóth, Laurent Millet, Leeli Amon, Barbara Lang, Morten Fischer Mortensen, Willy Tinner, Elizabeth S. Jeffers, F. Verbruggen, Stéphanie Samartin, Emmy I. Lammertsma, Boris P. Ilyashuk, Siim Veski, Nelleke Van Asch, Spassimir Tonkov, Stephen J. Brooks, Hilary H. Birks, Marjolein Hazekamp, Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Vrije Universiteit Amsterdam [Amsterdam] (VU), Laboratoire d'Economie Dionysien (LED), Université Paris 8 Vincennes-Saint-Denis (UP8), Transport Research Laboratory, TRL, Department of Medical Biochemistry, University of Amsterdam [Amsterdam] (UvA), Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Oeschger Centre for Climate Change Research (OCCR), University of Bern, Department of Biology, Department of Biological Sciences [Bergen] (BIO / UiB), University of Bergen (UiB)-University of Bergen (UiB), Department of Science Education [Copenhagen], Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU), Palaeoecology, Institute of Environmental Biology, Utrecht University [Utrecht], Earth and Climate, Amsterdam Global Change Institute, Vrije Univ Amsterdam, Amsterdam, Netherlands, Laboratoire Chrono-environnement - UFC (UMR 6249) (LCE), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), University of Oxford [Oxford]-University of Oxford [Oxford], Jet Propulsion Laboratory ( JPL ), NASA-California Institute of Technology ( CALTECH ), Laboratoire d'Economie Dionysien ( LED ), Université Paris 8 Vincennes-Saint-Denis ( UP8 ), University of Amsterdam [Amsterdam] ( UvA ), Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC ), Oeschger Centre for Climate Change Research ( OCCR ), Department of Science Education, and University of Copenhagen ( KU )

Subjects
010506 paleontology, Multidisciplinary, 010504 meteorology & atmospheric sciences, Meteorology, [SDE.MCG]Environmental Sciences/Global Changes, General Physics and Astronomy, Climate change, General Chemistry, 01 natural sciences, General Biochemistry, Genetics and Molecular Biology, Article, [ SDE.MCG ] Environmental Sciences/Global Changes, 13. Climate action, General Circulation Model, Climatology, SDG 13 - Climate Action, Environmental science, Common spatial pattern, Climate model, Glacial period, Holocene, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

Comparisons of climate model hindcasts with independent proxy data are essential for assessing model performance in non-analogue situations. However, standardized palaeoclimate data sets for assessing the spatial pattern of past climatic change across continents are lacking for some of the most dynamic episodes of Earth's recent past. Here we present a new chironomid-based palaeotemperature dataset designed to assess climate model hindcasts of regional summer temperature change in Europe during the late-glacial and early Holocene. Latitudinal and longitudinal patterns of inferred temperature change are in excellent agreement with simulations by the ECHAM-4 model, implying that atmospheric general circulation models like ECHAM-4 can successfully predict regionally diverging temperature trends in Europe, even when conditions differ significantly from present. However, ECHAM-4 infers larger amplitudes of change and higher temperatures during warm phases than our palaeotemperature estimates, suggesting that this and similar models may overestimate past and potentially also future summer temperature changes in Europe.

Published
2014
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6. Regional climate model simulations for Europe at 6 and 0.2 k BP: sensitivity to changes in anthropogenic deforestation

Author

Benjamin Smith, Mihkel Kangur, Ralph Fyfe, Małgorzata Latałowa, Thomas Giesecke, Sebastian Wagner, Anne E. Bjune, Basil A. S. Davis, Heikki Seppä, Anne Birgitte Nielsen, Laimdota Kalnina, Harry John Betteley Birks, Erik Kjellström, Shinya Sugita, A.K Trondman, Petr Kuneš, Achille Mauri, Marie-José Gaillard, Ulla Kokfelt, Jed O. Kaplan, Laurent Marquer, Florence Mazier, Anneli Poska, Gustav Strandberg, W.O. van der Knaap, Swedish Meteorological and Hydrological Institute (SMHI), Department of Physical Geography and Ecosystem Science [Lund], Lund University [Lund], Helmholtz-Zentrum Geesthacht (GKSS), Department of Biology and Environmental Science, Institute for Environmental Sciences [Geneva] (ISE), University of Geneva [Switzerland], Department of Biological Sciences [Bergen] (BIO / UiB), University of Bergen (UiB), Bjerknes Centre for Climate Research (BCCR), University of Bergen (UiB)-University of Bergen (UiB), Uni Research Climate, Uni Research Ltd, School of Geography, Earth and Environmental Sciences [Plymouth] (SoGEES), Plymouth University, Department of Palynology and Climate Dynamics, Georg-August-University [Göttingen]-Georg-August-University [Göttingen], Faculty of Geography and Earth Sciences [Riga], University of Latvia (LU), Institute of Ecology, Tallinn University, Institute of Plant Sciences, University of Bern-University of Bern, Center for Permafrost (CENPERM), Department of Geosciences and Natural Resource Management [Copenhagen] (IGN), Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU)-Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU), Department of Botany, Faculty of Science, Laboratory of Palaeoecology and Archaeology, University of Gdańsk (UG)-University of Gdańsk (UG), Géographie de l'environnement (GEODE), Centre National de la Recherche Scientifique (CNRS)-Université Toulouse - Jean Jaurès (UT2J), Department of Geology [Lund], Equipe Autre (R&D), Sciences et Technologies de la Musique et du Son (STMS), Institut de Recherche et Coordination Acoustique/Musique (IRCAM)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche et Coordination Acoustique/Musique (IRCAM)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Department of Geosciences and Geography [Helsinki], Falculty of Science [Helsinki], University of Helsinki-University of Helsinki, Université Toulouse - Jean Jaurès (UT2J)-Centre National de la Recherche Scientifique (CNRS), Department of Geosciences and Geography, Université de Genève = University of Geneva (UNIGE), Georg-August-University = Georg-August-Universität Göttingen-Georg-August-University = Georg-August-Universität Göttingen, 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), Charles University [Prague] (CU), Université Toulouse - Jean Jaurès (UT2J), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), and Helsingin yliopisto = Helsingfors universitet = University of Helsinki-Helsingin yliopisto = Helsingfors universitet = University of Helsinki

Subjects
VEGETATION DYNAMICS, Climate Research, LAND-COVER CHANGES, Mathematics and natural scienses: 400::Geosciences: 450::Meteorology: 453 [VDP], lcsh:Environmental protection, Stratigraphy, education, Potential natural vegetation, 580 Plants (Botany), Climate model, Klimatforskning, NORTHERN SWEDEN, Matematikk og naturvitenskap: 400::Geofag: 450::Meteorologi: 453 [VDP], lcsh:Environmental pollution, Deforestation, Evapotranspiration, lcsh:TD169-171.8, anthropogenic deforestation, lcsh:Environmental sciences, Holocene, 1172 Environmental sciences, ddc:910, HOLOCENE CLIMATE, lcsh:GE1-350, Global and Planetary Change, Land use, Mathematics and natural scienses: 400::Zoology and botany: 480::Vegetation history: 495 [VDP], IBERIAN PENINSULA, Paleontology, Vegetation, [SHS.GEO]Humanities and Social Sciences/Geography, 15. Life on land, Albedo, LAKE-LEVEL FLUCTUATIONS, Europe, LAST GLACIAL MAXIMUM, Regional climate, deforestation, 13. Climate action, POLLEN DATA, Climatology, lcsh:TD172-193.5, [SDE]Environmental Sciences, SURFACE CLIMATE, BALTIC SEA, Matematikk og naturvitenskap: 400::Zoologiske og botaniske fag: 480::Vegetasjonshistorie: 495 [VDP]
Abstract

International audience; This study aims to evaluate the direct effects of anthropogenic deforestation on simulated climate at two contrasting periods in the Holocene, ∼ 6 and ∼ 0.2 k BP in Eu-rope. We apply the Rossby Centre regional climate model RCA3, a regional climate model with 50 km spatial resolution, for both time periods, considering three alternative descriptions of the past vegetation: (i) potential natural vegetation (V) simulated by the dynamic vegetation model LPJ-GUESS, (ii) potential vegetation with anthro-pogenic land use (deforestation) from the HYDE3.1 (History Database of the Global Environment) scenario (V + H3.1), and (iii) potential vegetation with anthropogenic land use Published by Copernicus Publications on behalf of the European Geosciences Union. 662 G. Strandberg et al.: Sensitivity to changes in anthropogenic deforestation from the KK10 scenario (V + KK10). The climate model results show that the simulated effects of deforestation depend on both local/regional climate and vegetation characteristics. At ∼ 6 k BP the extent of simulated deforestation in Europe is generally small, but there are areas where deforestation is large enough to produce significant differences in summer temperatures of 0.5–1 • C. At ∼ 0.2 k BP, extensive deforestation , particularly according to the KK10 model, leads to significant temperature differences in large parts of Europe in both winter and summer. In winter, deforestation leads to lower temperatures because of the differences in albedo between forested and unforested areas, particularly in the snow-covered regions. In summer, deforestation leads to higher temperatures in central and eastern Europe because evapotranspiration from unforested areas is lower than from forests. Summer evaporation is already limited in the south-ernmost parts of Europe under potential vegetation conditions and, therefore, cannot become much lower. Accordingly , the albedo effect dominates in southern Europe also in summer, which implies that deforestation causes a decrease in temperatures. Differences in summer temperature due to deforestation range from −1 • C in southwestern Europe to +1 • C in eastern Europe. The choice of anthropogenic land-cover scenario has a significant influence on the simulated climate, but uncertainties in palaeoclimate proxy data for the two time periods do not allow for a definitive discrimination among climate model results.

Published
2014
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7. The pace of Holocene vegetation change – testing for synchronous developments

Author

Keith Bennett, Elisaveta Bozilova, Walter Finsinger, Thomas Giesecke, Angelica Feurdean, Petr Pokorný, Spasimir Tonkov, Heikki Seppä, Manfred Rösch, Steffen Wolters, Anne E. Bjune, H. John B. Birks, Verushka Valsecchi, Cynthia A. Froyd, Department of Geography, University of Liverpool, Centre de Bio-Archéologie et d'Ecologie (CBAE), 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)-Université Montpellier 2 - Sciences et Techniques (UM2), University of Helsinki, Institut des Sciences de l'Evolution de Montpellier (UMR ISEM), École pratique des hautes études (EPHE), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Montpellier (UM)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre National de la Recherche Scientifique (CNRS)-Institut de recherche pour le développement [IRD] : UR226

Subjects
010506 paleontology, Archeology, 010504 meteorology & atmospheric sciences, [SDE.MCG]Environmental Sciences/Global Changes, Population, Climate change, 01 natural sciences, [SDV.SA.SF]Life Sciences [q-bio]/Agricultural sciences/Silviculture, forestry, Forest ecology, education, skin and connective tissue diseases, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Holocene, Ecology, Evolution, Behavior and Systematics, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, education.field_of_study, Global and Planetary Change, biology, Geology, Vegetation, 15. Life on land, [SDV.BV.BOT]Life Sciences [q-bio]/Vegetal Biology/Botanics, biology.organism_classification, [SDV.BIBS]Life Sciences [q-bio]/Quantitative Methods [q-bio.QM], [SDE.ES]Environmental Sciences/Environmental and Society, Alnus glutinosa, 13. Climate action, Climatology, Spatial ecology, Biological dispersal, sense organs, [SDE.BE]Environmental Sciences/Biodiversity and Ecology
Abstract

Mid to high latitude forest ecosystems have undergone several major compositional changes during the Holocene. The temporal and spatial patterns of these vegetation changes hold potential information to their causes and triggers. Here we test the hypothesis that the timing of vegetation change was synchronous on a sub-continental scale, which implies a common trigger or a step-like change in climate parameters. Pollen diagrams from selected European regions were statistically divided into assemblage zones and the temporal pattern of the zone boundaries analysed. The results show that the temporal pattern of vegetation change was significantly different from random. Times of change cluster around 8.2, 4.8, 3.7, and 1.2 ka, while times of higher than average stability were found around 2.1 and 5.1 ka. Compositional changes linked to the expansion of Corylus avellana and Alnus glutinosa centre around 10.6 and 9.5 ka, respectively. A climatic trigger initiating these changes may have occurred 0.5 to 1 ka earlier, respectively. The synchronous expansion of C. avellana and A. glutinosa exemplify that dispersal is not necessarily followed by population expansion. The partly synchronous, partly random expansion of A. glutinosa in adjacent European regions exemplifies that sudden synchronous population expansions are not species specific traits but vary regionally.

Published
2011
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8. Pollen-based continental climate reconstructions at 6 and 21 ka: a global synthesis

Author

Iain Colin Prentice, John W. Williams, Shinya Sugita, Sandy P. Harrison, Bryan N. Shuman, Heikki Seppä, T I Harrison-Prentice, Konrad Gajewski, Odile Peyron, A. E. Viau, Basil A. S. Davis, Patrick J. Bartlein, Marko Scholze, Simon Brewer, Joel Guiot, Robert S. Thompson, A S Henderson, Haibin Wu, Simon Connor, School of Geographical Sciences [Bristol], University of Bristol [Bristol], Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Collège de France (CdF)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Institut National de la Recherche Agronomique (INRA), Department of Psychology [Austin] (University of Texas), University of Texas at Austin [Austin], School of Natural Sciences ? Chemistry, Bedson Building, Laboratoire Chrono-environnement - UFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Dpt Biological Sciences, Macquarie University, Macquarie University, Department of Geology, P.O. Box 64, Department of Health Sciences [Leicester], University of Leicester, Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA), Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS), School of Geographical Sciences, Centre européen de recherche et d'enseignement de géosciences de l'environnement ( CEREGE ), Centre National de la Recherche Scientifique ( CNRS ) -Institut de Recherche pour le Développement ( IRD ) -Aix Marseille Université ( AMU ) -Collège de France ( CdF ) -Institut National de la Recherche Agronomique ( INRA ) -Institut national des sciences de l'Univers ( INSU - CNRS ), Department of Psychology [Austin] ( University of Texas ), Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC ), Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Chrono-environnement (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), and Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)

Subjects
Past 21,000 years, 010506 paleontology, Atmospheric Science, Plant Functional Types, 010504 meteorology & atmospheric sciences, Plant functional types, C-14 Yr Bp, [SDE.MCG]Environmental Sciences/Global Changes, Climate change, medicine.disease_cause, 01 natural sciences, Palaeovegetation palaeoclimate reconstructions, Pollen, Mid-Holocene, medicine, Glacial period, General-circulation model, Pmip2 coupled simulations, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Eastern North-America, Subfossil, General-Circulation Model, Last Glacial Maximum, Past 21,000 Years, Modern analog technique, Macrofossil, Last glacial maximum, Modern Analog Technique, Leaf-area index, Lake Status Data, Reconstruction uncertainties, [ SDE.MCG ] Environmental Sciences/Global Changes, Lake status data, Pmip2 Coupled Simulations, 13. Climate action, Climatology, Paleoclimate Modelling Intercomparison Project, Interglacial, Plant macrofossils, Climate model evaluation, Geology, Leaf-Area Index
Abstract

Subfossil pollen and plant macrofossil data derived from C-14-dated sediment profiles can provide quantitative information on glacial and interglacial climates. The data allow climate variables related to growing-season warmth, winter cold, and plant-available moisture to be reconstructed. Continental-scale reconstructions have been made for the mid-Holocene (MH, around 6 ka) and Last Glacial Maximum (LGM, around 21 ka), allowing comparison with palaeoclimate simulations currently being carried out as part of the fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change. The synthesis of the available MH and LGM climate reconstructions and their uncertainties, obtained using modern-analogue, regression and model-inversion techniques, is presented for four temperature variables and two moisture variables. Reconstructions of the same variables based on surface-pollen assemblages are shown to be accurate and unbiased. Reconstructed LGM and MH climate anomaly patterns are coherent, consistent between variables, and robust with respect to the choice of technique. They support a conceptual model of the controls of Late Quaternary climate change whereby the first-order effects of orbital variations and greenhouse forcing on the seasonal cycle of temperature are predictably modified by responses of the atmospheric circulation and surface energy balance. UK Natural Environment Research Council; International Quaternary Association (INQUA) [0801]; QUEST (Quantifying Uncertainties in the Earth System) programme; US National Science Foundation; Natural Sciences and Engineering Research Council of Canada (NSERC); Canadian Foundation for Climate and Atmospheric Sciences (CFCAS); Natural Environment Research Council [quest010001, NE/F014600/1] info:eu-repo/semantics/publishedVersion

Published
2011
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9. The spatial and temporal complexity of the Holocene thermal maximum

Author

Hugues Goosse, Didier M. Roche, Heikki Seppä, Hans Renssen, Oliver Heiri, Thierry Fichefet, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Modélisation du climat (CLIM), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, 010506 paleontology, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Orbital forcing, 01 natural sciences, Ice-sheet model, 13. Climate action, Climatology, Interglacial, Deglaciation, General Earth and Planetary Sciences, Cryosphere, Ice sheet, Meltwater, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Geology, Holocene, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

The Holocene thermal maximum, a period of relatively warm climate between 11,000 and 5,000 years ago1, 2, is most clearly recorded in the middle and high latitudes2, 3 of the Northern Hemisphere, where it is generally associated with the local orbitally forced summer insolation maximum. However, proxy-based reconstructions have shown that both the timing and magnitude of the warming vary substantially between different regions2, 3, 4, suggesting the involvement of extra feedbacks and forcings. Here, we simulate the Holocene thermal maximum in a coupled global ocean–atmosphere–vegetation model. We find that before 7,000 years ago, summers were substantially cooler over regions directly influenced by the presence of the Laurentide ice sheet, whereas other regions of the Northern Hemisphere were dominated by orbital forcing. Our simulations suggest that the cool conditions arose from a combination of the inhibition of Labrador Sea deep convection by the flux of meltwater from the ice sheet, which weakened northward heat transport by the ocean, and the high surface albedo of the ice sheet. We thus conclude that interglacial climate is highly sensitive to relatively small changes in ice-sheet configuration.

Published
2009
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10. Anticyclonic atmospheric circulation as an analogue for the warm and dry mid-Holocene summer climate in central Scandinavia

Author

Deliang Chen, Karin Antonsson, Heikki Seppä, Department of Earth Sciences [Uppsala], Uppsala University, Earth Sciences Centre, University of Gothenburg (GU), Department of Geology, P.O. Box 64, and EGU, Publication

Subjects
010506 paleontology, 010504 meteorology & atmospheric sciences, Atmospheric circulation, Stratigraphy, lcsh:Environmental protection, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Atmospheric sciences, 01 natural sciences, lcsh:Environmental pollution, Dominance (ecology), lcsh:TD169-171.8, Precipitation, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Holocene, lcsh:Environmental sciences, 0105 earth and related environmental sciences, lcsh:GE1-350, Global and Planetary Change, Climate pattern, Paleontology, [SDU.ENVI] Sciences of the Universe [physics]/Continental interfaces, environment, Anticyclone, 13. Climate action, Middle latitudes, Climatology, lcsh:TD172-193.5, [SDU.STU] Sciences of the Universe [physics]/Earth Sciences, Environmental science, Climate model
Abstract

Climate reconstructions from central Scandinavia suggest that annual and summer temperatures were rising during the early Holocene and reached their maximum after 8000 cal yr BP. The period with highest temperatures was characterized by increasingly low lake-levels and dry climate, with driest and warmest conditions at about 7000 to 5000 cal yr BP. We compare the reconstructed climate pattern with simulations of a climate model for the last 9000 years and show that the model, which is predominantly driven by solar insolation patterns, suggests less prominent mid-Holocene dry and warm period in Scandinavia than the reconstructions. As an additional explanation for the reconstructed climate, we argue that the trend from the moist early Holocene towards dry and warm mid-Holocene was caused by a changing atmospheric circulation pattern with a mid-Holocene dominance of summer-time anticyclonic circulation. An extreme case of the anticyclonic conditions is the persistent blocking high, an atmospheric pressure pattern that at present often causes long spells of particularly dry and warm summer weather, or "Indian summers". The argument is tested with daily instrumental temperature and precipitation records in central Sweden and an objective circulation classification based on surface air pressure over the period 1900–2002. We conclude that the differences between the precipitation and temperature climates under anticyclonic and non-anticyclonic conditions are significant. Further, warm and dry combination, as indicated by mid-Holocene reconstructions, is a typical pattern under anticyclonic conditions. These results indicate that the presented hypothesis for the mid-Holocene climate is likely valid.

Published
2008

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