Growing Season Temperatures in Europe and Climate Forcings Over the Past 1400 Years

• Published in: PLoS ONE
• Main Authors: Guiot, Joel, Corona, Christophe, Brewer, S., Chalié, F., Daux, Valérie, Édouard, Jean-Louis, Girardclos, O., Guibal, F., Lambert, G., Masson‐Delmotte, V., Pichard, G., Servonnat, J., Swingedouw, D., Thomas, A., Yiou, P.
• Other Authors: 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), Ecosystèmes continentaux et risques environnementaux (ECCOREV), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Institute of geological science, University of Berne, 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), Géochrononologie Traceurs Archéométrie (GEOTRAC), 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), Glaces et Continents, Climats et Isotopes Stables (GLACCIOS), Modelling the Earth Response to Multiple Anthropogenic Interactions and Dynamics (MERMAID), Extrèmes : Statistiques, Impacts et Régionalisation (ESTIMR), ANR-06-VULN-0010,ESCARSEL,Evolution Séculaire du Climat dans les régions circum-Atlantiques et Réponse de Systèmes Eco-Lacustres(2006)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2010
• Subjects: Seasons; Climate change; Europe; Ice cores; Pollen; Summer; Volcanoes; Glaciers; [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology; [SDE.MCG]Environmental Sciences/Global Changes; ice core
• Online Access: https://hal.archives-ouvertes.fr/hal-01116819; https://hal.archives-ouvertes.fr/hal-01116819/document; https://hal.archives-ouvertes.fr/hal-01116819/file/journal.pone.0009972.PDF; https://doi.org/10.1371/journal.pone.0009972

International audience Background: The lack of instrumental data before the mid-19th-century limits our understanding of present warming trends. In the absence of direct measurements, we used proxies that are natural or historical archives recording past climatic changes. A gridded reconstruction of spring-summer temperature was produced for Europe based on tree-rings, documentaries, pollen assemblages and ice cores. The majority of proxy series have an annual resolution. For a better inference of long-term climate variation, they were completed by low-resolution data (decadal or more), mostly on pollen and ice-core data.Methodology/Principal Findings: An original spectral analog method was devised to deal with this heterogeneous dataset, and to preserve long-term variations and the variability of temperature series. So we can replace the recent climate changes in a broader context of the past 1400 years. This preservation is possible because the method is not based on a calibration (regression) but on similarities between assemblages of proxies. The reconstruction of the April-September temperatures was validated with a Jack-knife technique. It was also compared to other spatially gridded temperature reconstructions, literature data, and glacier advance and retreat curves. We also attempted to relate the spatial distribution of European temperature anomalies to known solar and volcanic forcings.Conclusions: We found that our results were accurate back to 750. Cold periods prior to the 20th century can be explained partly by low solar activity and/or high volcanic activity. The Medieval Warm Period (MWP) could be correlated to higher solar activity. During the 20th century, however only anthropogenic forcing can explain the exceptionally high temperature rise. Warm periods of the Middle Age were spatially more heterogeneous than last decades, and then locally it could have been warmer. However, at the continental scale, the last decades were clearly warmer than any period of the last 1400 years. The ...