Scenario-based analysis of the projected mean changes in the monthly frequency of hot days based on the latest CMIP6 simulations along European zonal segments
Abstract
The potential changes in extreme hot temperature (represented by TX35, i.e. the number of days with maximum temperature above 35 °C) are analysed, using the latest global climate model simulations ensemble mean of CMIP6, available in the new tool of the IPCC, namely, the Interactive Atlas. The analysis is carried out over Europe with a special focus on Central and Southern Europe. Our aim is to evaluate the spatial patterns within the projected changes in the period 2081–2100 that can be further used in several sectors, e.g. in the health sector, which is especially affected by the potential increase of extremely hot conditions. For this purpose, the projected changes of TX35 are compared to the reference-period 1995–2014 for four available scenarios from the newest scenario-family, namely, SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5 representing different mitigation and adaptation challenges. As the projected increase is not limited to summer, the monthly-scale analysis is extended to the period from May to September. A novel approach is used to investigate the major factors in the projected changes, namely, six zonal segments are selected over Europe, covering the relevant parts of the continent with appropriate distances between them. The most important driving factors of the projected changes of TX35 are identified as follows: (i) the differences between regions due to their north-south or east-west locations (i.e. zonal and continental effects), (ii) elevation above sea level, (iii) the different anthropogenic effects (i.e. different scenarios). The results show that the key factor in the projected changes is the difference between anthropogenic effects. Furthermore, the sea-land surface differences also have substantial effect on the projected changes of TX35, especially in the southern regions. Continentality and elevation show only smaller effects overall.
References
ALVAREZ, I., DIAZ-POSO, A., LORENZO, M.N. and ROYE, D. 2024. Heat index historical trends and projections due to climate change in the Mediterranean basin based on CMIP6. Atmospheric Research 308. 107512. https://doi.org/10.1016/j.atmosres.2024.107512
ANDRADE, C., LEITE, S.M. and SANTOS, J.A. 2012. Temperature extremes in Europe: overview of their driving atmospheric patterns. Natural Hazards and Earth System Sciences 12. 1671–1691. https://doi.org/10.5194/nhess-12-1671-2012
CARDIL, A., MOLINA, D.M. and KOBZIAR, L.N. 2014. Extreme temperature days and their potential impacts on southern Europe. Natural Hazards and Earth System Sciences 14. 3005–3014. https://doi.org/10.5194/nhess-14-3005-2014
COGATO, A., MEGGIO, F., DE ANTONI MIGLIORATI, M. and MARINELLO, F. 2019. Extreme weather events in agriculture: A systematic review. Sustainability 11. (9): 2547. https://doi.org/10.3390/su11092547
C3S 2025. The 2024 Annual Climate Summary: Global Climate Highlights 2024. Copernicus Climate Change Services (C3S). Available at https://climate.copernicus.eu/global-climate-highlights-2024
COPPOLA, E., NOGHEROTTO, R., CIARLO, J.M., GIORGI, F., VAN MEIJGAARD, E., KADYGROV, N., ILES, C., CORRE, L., SANDSTAD, M., SOMOT, S., NABAT, P., VAUTARD, R., LEVAVASSEUR, G., SCHWINGSCHACKL, C., SILLMANN, J., KJELLSTRÖM, E., NIKULIN, G., AALBERS, E., LENDERINK, G., CHRISTENSEN, O.B., BOBERG, F., SORLAND, S.L., DEMORY, M-E., BÜLOW, K., TEICHMANN, C., WARRACH-SAGI, K. and WULFMEYER, V. 2021. Assessment of the European climate projections as simulated by the large EURO-CORDEX regional and global climate model ensemble. Journal of Geophysical Research: Atmospheres 126. (4): e2019JD032356. https://doi.org/10.1029/2019JD032356
ENGDAW, M.M., STEINER, A.K., HEGERL, G.C. and BALLINGER, A.P. 2023. Attribution of observed changes in extreme temperatures to anthropogenic forcing using CMIP6 models. Weather and Climate Extremes 39. 100548. https://doi.org/10.1016/j.wace.2023.100548
EYRING, V., BONY, S., MEEHL, G.A., SENIOR, C.A., STEVENS, B., STOUFFER, R.J. and TAYLOR, K.E. 2016. Overview of the Coupled Model Intercomparison Project Phase 6 (CMIP6) experimental design and organization. Geoscientific Model Development 9. 1937–1958. https://doi.org/10.5194/gmd-9-1937-2016
EYRING, V., GENTINE, P., CAMPS-VALLS, G., LAWRENCE, D.M. and REICHSTEIN, M. 2024. AI-empowered next-generation multiscale climate modelling for mitigation and adaptation. Nature Geoscience 17. 963–971. https://doi.org/10.1038/s41561-024-01527-w
FAN, X., DUAN, Q., SHEN, C., WU, Y. and XING, C. 2020. Global surface air temperatures in CMIP6: Historical performance and future changes. Environmental Research Letters 15. (10): 104056. https://doi.org/10.1088/1748-9326/abb051
GALLO, E., QUIJAL-ZAMORANO, M., MÉNDEZ TURRUBIATES, R.F., TONNE, C., BASAGAÑA, X., ACHEBAK, H. and BALLESTER, J. 2024. Heat-related mortality in Europe during 2023 and the role of adaptation in protecting health. Nature Medicine 30. 3101–3105. https://doi.org/10.1038/s41591-024-03186-1
GUTIÉRREZ, J.M., JONES, R.G., NARISMA, G.T., ALVES, L.M., AMJAD, M., GORODETSKAYA, I.V., GROSE, M., KLUTSE, N.A.B., KRAKOVSKA, S., LI, J., MARTÍNEZ-CASTRO, D., MEARNS, L.O., MERNILD, S.H., NGO-DUC, T., VAN DEN HURK, B. and YOON, J.-H. 2021. Atlas. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. Eds.: MASSON-DELMOTTE, V., ZHAI, P., PIRANI, A., CONNORS, S.L., PÉAN, C., CHEN, Y., GOLDFARB, L., GOMIS, M.I., MATTHEWS, J.B.R., BERGER, S., HUANG, M, YELEKÇI, O., YU, R., ZHOU, B., LONNOY, E., MAYCOCK, T.K., WATERFIELD, T., LEITZELL, K. and CAUD, N., Cambridge, UK and New York, NY, USA, Cambridge University Press, 1927–2058. https://doi.org/10.1017/9781009157896.021. Interactive Atlas available from IPCC WGI Interactive Atlas
IPCC 2021. Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. Eds.: MASSON-DELMOTTE, V., ZHAI, P., PIRANI, A., CONNORS, S.L., PÉAN, C., BERGER, S., CAUD, N., CHEN, Y., GOLDFARB, L., GOMIS, M.I., HUANG, M., LEITZELL, K., LONNOY, E., MATTHEWS, J.B.R., MAYCOCK, T.K., WATERFIELD, T., YELEKÇI, O., YU, R. and ZHOU, B. Cambridge, UK and New York, NY, USA, Cambridge University Press. https://doi.org/10.1017/9781009157896
KING, A.D., KNUTTI, R., UHE, P., MITCHELL, D.M., LEWIS, S.C., ARBLASTER, J.M. and FREYCHET, N. 2018. On the linearity of local and regional temperature changes from 1.5 °C to 2 °C of global warming. Journal of Climate 31. 7495–7514. https://doi.org/10.1175/JCLI-D-17-0649.1
LORENZ, R., STALHANDSKE, Z. and FISCHER, E.M. 2019. Detection of a climate change signal in extreme heat, heat stress, and cold in Europe from observations. Geophysical Research Letters 46. (14): 8363–8374. https://doi.org/10.1029/2019GL082062
LÜTHI, S., FAIRLESS, C., FISCHER, E.M., SCOVRONICK, N., ARMSTRONG, B., DE SOUSA ZANOTTI STAGLIORIO COELHO, M., GUO, Y.L., GUO, Y., HONDA, Y., HUBER, V., KYSELÝ, J., LAVIGNE, E., ROYÉ, D., RYTI, N., SILVA, S., URBAN, A., GASPARRINI, A., BRESCH, D.N., VICEDO-CABRERA, A.M. and Multi-Country Multi-City (MCC) Collaborative Research Network 2023. Rapid increase in the risk of heat-related mortality. Nature Communications 14. (1): 4894. https://doi.org/10.1038/s41467-023-40599-x
O’NEILL, B.C., KRIEGLER, E., EBI, K.L., KEMP-BENEDICT, E., RIAHI, K., ROTHMAN, D.S., VAN RUIJVEN, B.J., VAN VUUREN, D.P., BIRKMANN, J., KOK, K., LEVY, M. and SOLECKI, W. 2017. The roads ahead: Narratives for shared socioeconomic pathways describing world futures in the 21st century. Global Environmental Change 42. 169–180. https://doi.org/10.1016/j.gloenvcha.2015.01.004
ROJAS-DOWNING, M.M., NEJADHASHEMI, A.P., HARRIGAN, T. and WOZNICKI, S.A. 2017. Climate change and livestock: Impacts, adaptation, and mitigation. Climate Risk Management 16. 145–163. https://doi.org/10.1016/j.crm.2017.02.001
SCHAEFFER, R., SZKLO, A.S., DE LUCENA, A.F.P., BORBA, B.S.M.C., NOGUEIRA, L.P.P., FLEMING, F.P., TROCCOLI, A., HARRISON, M. and BOULAHYA, M.S. 2012. Energy sector vulnerability to climate change: A review. Energy 38. (1): 1–12. https://doi.org/10.1016/j.energy.2011.11.056
SOUSA, P.M., TRIGO, R.M., BARRIOPEDRO, D., SOARES, P.M., SANTOS J.A. 2018. European temperature responses to blocking and ridge regional patterns. Climate Dynamics 50. 457–477. https://doi.org/10.1007/s00382-017-3620-2
SRIVASTAVA, A.K., WEHNER, M., BONFILS, C., ULLRICH, P.A. and RISSER, M. 2024. Local hydro-climate drives differential warming rates between regular summer days and extreme hot days in the Northern Hemisphere. Weather and Climate Extremes 45. 100709. https://doi.org/10.1016/j.wace.2024.100709
SUAREZ-GUTIERREZ, L., MÜLLER, W.A. and MAROTZKE, J. 2023. Extreme heat and drought typical of an end-of-century climate could occur over Europe soon and repeatedly. Communications Earth and Environment 4. (1): 415. https://doi.org/10.1038/s43247-023-01075-y
SULIKOWSKA, A. and WYPYCH, A. 2021. Seasonal variability of trends in regional hot and warm temperature extremes in Europe. Atmosphere 12. (5): 612. https://doi.org/10.3390/atmos12050612
TAYLOR, K.E., STOUFFER, R.J. and MEEHL, G.A. 2012. An overview of CMIP5 and the experiment design. Bulletin of the American Meteorological Society 93. 485–498. https://doi.org/10.1175/BAMS-D-11-00094.1
TEBALDI, C. and KNUTTI, R. 2018. Evaluating the accuracy of climate change pattern emulation for low warming targets. Environmental Research Letters 13. (5): 055006. https://doi.org/10.1088/1748-9326/aabef2
VAN VUUREN, D.P., EDMONDS, J., KAINUMA, M., RIAHI, K., THOMSON, A., HIBBARD, K., HURTT, G.C., KRAM, T., KREY, V., LAMARQUE, J-F., MASUI, T., MEINSHAUSEN, M., NAKICEN¬OVIC, N., SMITH, S.J. and ROSE, S.K. 2011. The representative concentration pathways: An overview. Climatic Change 109. 5–31. https://doi.org/10.1007/s10584-011-0148-z
WILKS, D.S. 2006. Statistical Methods in the Atmospheric Sciences. 2nd edition. London, Academic Press.
WMO 2025. State of the Global Climate in 2024. WMO-No. 1368. Geneva, WMO.
WOBUS, C., ZARAKAS, C., MALEK, P., SANDERSON, B., CRIMMINS, A., KOLIAN, M., SAROFIM, M. and WEAVER, C.P. 2018. Reframing future risks of extreme heat in the United States. Earth's Future 6. (9): 1323–1335. https://doi.org/10.1029/2018EF000943
Copyright (c) 2026 Ferenc Tamás Divinszki, Anna Kis, Rita Pongrácz
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
