Past long-term summer warming over western Europe in new generation climate models: role of large-scale atmospheric circulation

• Published in: Environmental Research Letters
• Main Authors: Boe, Julien, Terray, Laurent, Moine, Marie-Pierre, Valcke, Sophie, Bellucci, Alessio, Drijfhout, Sybren, Haarsma, Reindert Julius, Lohmann, Katja, Putrasahan, Dian, Roberts, Christopher, Roberts, Malcolm, Scoccimarro, Enrico, Seddon, Jon, Senan, Retish, Wyser, Klaus
• Other Authors: CERFACS Toulouse, Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centro Euro-Mediterraneo per i Cambiamenti Climatici Bologna (CMCC), Royal Netherlands Meteorological Institute (KNMI), Max-Planck-Institut für Meteorologie (MPI-M), Max-Planck-Gesellschaft, European Centre for Medium-Range Weather Forecasts (ECMWF), Swedish Meteorological and Hydrological Institute (SMHI)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2020
• Subjects: climate change; Europe; summer warming; atmospheric circulation; trends; model evaluation; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology; North Atlantic; Sea ice
• Online Access: https://hal.science/hal-02908737; https://hal.science/hal-02908737/document; https://hal.science/hal-02908737/file/Boe%CC%81_2020_Environ._Res._Lett._15_084038.pdf; https://doi.org/10.1088/1748-9326/ab8a89

International audience Past studies have concluded that climate models of previous generations tended to underestimate the large warming trend that has been observed in summer over western Europe in the last few decades. The causes of this systematic error are still not clear. Here, we investigate this issue with a new generation of climate models and systematically explore the role of large-scale circulation in that context. As an ensemble, climate models in this study warm less over western Europe and warm more over eastern Europe than observed on the 1951-2014 period, but it is difficult to conclude this is directly due to systematic errors given the large potential impact of internal variability. These differences in temperature trends are explained to an important extent by an anti-correlation of sea level pressure trends over the North Atlantic / Europe domain between models and observations. The observed trend tends to warm (cool) western (eastern) Europe but the simulated trends generally have the opposite effect, both in new generation and past generation climate models. The differences between observed and simulated sea level pressure trends are likely the result of systematic model errors, which might also impact future climate projections. Neither a higher resolution nor the realistic representation of the evolution of sea surface temperature and sea ice leads to a better simulation of sea level pressure trends.