Prof. em. Dr. Christoph Schär

News and Highlights

Km-resolution climate simulations over the Alps: Recent publications include:

Fosser, G., M. Gaetani, E.J. Kendon, M. Adinolfi, N. Ban, D. Belušić, C. Caillaud, J.A.M. Careto, E. Coppola, M.-E. Demory, H. de Vries, A. Dobler, H. Feldmann, K. Goergen, G. Lenderink, E. Pichelli, C. Schär, P.M.M. Soares, S. Somot and M.H. Tölle, 2024: Convection-permitting climate models offer more certain extreme rainfall projections. npj Clim. Atmos. Sci., 7, 51, external page https://doi.org/10.1038/s41612-024-00600-w

Estermann, R., J. Rajczak, P. Velasquez, R. Lorenz, and C. Schär, 2024: Projections of heavy precipitation characteristics over the Greater Alpine Region using a kilometer–resolution climate model ensemble. J. Geophys. Res. Atmos., submitted (preprint), https://polybox.ethz.ch/index.php/s/Zbw3y4UDrETjAom

We have also contributed to two papers on the first multi-model ensemble of regional climate simulations at kilometer-scale resolution:

Part 1: Ban, N., et al. 2021: Evaluation of precipitation. Clim. Dyn., 2021, https://doi.org/10.1007/s00382-021-05708-w |

Part 2: Pichelli, E., et al., 2021: Historical and future simulations of precipitation, https://doi.org/10.1007/s00382-021-05657-4  

Regional climate modeling in the tropical Atlantic: We have startet to use km-resolution climate models to investigate cloud feedbacks in the tropical and subtropical Atlantic. Tropical clouds represent one of the main challenges in climate change. Recent publications include:  

Heim, C., and C. Schär, 2024: Climate change response of tropical Atlantic clouds in a kilometer-resolution model. J. Geophys. Res. Atmos., 129, e2023JD038947, external page https://doi.org/10.1029/2023JD038947external page

Heim, C., Leutwyler, D., & Schär, C., 2023: Application of the pseudo-global warming approach in a kilometer-resolution climate simulation of the tropics.  J. Geophys. Res. Atmos., 128, e2022JD037958. external page https://doi.org/10.1029/2022JD037958

Liu, S., C. Zeman, S.L. Sørland, C. Schär, 2022: Systematic Calibration of a Convection-Resolving Model: Application over Tropical Atlantic. J. Geophys. Res. Atmos., 127, e2022JD037303. external page https://doi.org/10.1029/2022JD037303

Liu, S., C. Zeman, C. Schär, 2024: Dynamical downscaling of climate projections in the tropics. Geophys. Res. Letters., 51, e2023GL105733. external page https://doi.org/10.1029/2023GL105733

Software for pseudo-global warming approach: This approach is well suited for regional climate change scenarios. We have published a paper and associated software: Brogli, R., C. Heim, J. Mensch, S.L. Sørland, and C. Schär, 2023: The pseudo-global-warming (PGW) approach: Methodology, software package PGW4ERA5 v1.1, validation and sensitivity analyses. Geosci. Model Dev., 16, 907–926, external page https://doi.org/10.5194/gmd-16-907-2023

Prospects and challenges of km-resolution climate models: The crCLIM project has written an overview article on this topic: Schär, C., O. Fuhrer, A. Arteaga, N. Ban, C. Charpilloz, S. Di Girolamo, L. Hentgen, T. Hoefler, X. Lapillonne, D. Leutwyler, K. Osterried, D. Panosetti, S. Rüdisühli, L. Schlemmer, T. Schulthess, M. Sprenger, S. Ubbiali, H. Wernli, 2020: Kilometer-scale climate models: Prospects and challenges. Bull. American Meteorol. Soc., 101 (5), E567–E587, external page https://doi.org/10.1175/BAMS-D-18-0167.1

Mediterranean Amplification: Climate projections of the European summer climate exhibit an enhanced warming and drying over the Mediterranean. We have developped a new methodology and find that this peculier effect is partly due to changes in stratification, driven by changes in moist-adiabatic lapse-rate: Brogli, R., N. Kröner, S.L. Sørland, D. Lüthi and C. Schär, 2019: The Role of Hadley Circulation and Lapse-Rate Changes for the Future European Summer Climate. J. Climate, 32, 385-404, external page https://doi.org/10.1175/JCLI-D-18-0431.1

Latsis Symposium 2019: The Latsis Symposium 2019 has been awarded to a consortium led by Christoph Schär. The Symposium will be about "High-Resolution Climate Modeling: Perspectives and Challenges". Further info can be found at http://latsis2019.ethz.ch/

Performance of GCM-RCM model chains: It is a common belief that the errors in GCM-RCM model chains behave approximately additive. If this hypothesis was true, the application of model chains would not lead to any intrinsic improvement except for higher-resolution details. Here we investigate the bias patterns and climate change signals of two RCMs. Results show that the biases of the RCMs and GCMs are not additive and not independent. The two RCMs are systematically reducing the biases and modifying the climate change signals of the driving GCMs, even on scales that are considered well resolved by the driving GCMs: Sørland, S.L., C. Schär, D. Lüthi and E. Kjellström, 2018: Regional climate models reduce biases of global models and project smaller European summer warming. Env. Res. Letters, 13, 074017, external page https://doi.org/10.1088/1748-9326/aacc77

High-resolution near-global simulations on GPUs: Within the crCLIM project we contributed to a demonstration project that conducted near-global COSMO simulations on GPUs, with resolutions of up to 1 km. The discussion paper also provides detailed information on the scaling: Fuhrer O., T. Chadha, T. Hoefler, G. Kwasniewski, X. Lapillonne, D. Leutwyler, D. Lüthi, C. Osuna, C. Schär, T.C. Schulthess, H. Vogt, 2018. Near-global climate simulation at 1 km resolution: establishing a performance baseline on 4’888 GPUs with COSMO 5.0. Geosci. Model Develop., Geosci. Model Develop., 11, 1665–1681, external page https://doi.org/10.5194/gmd-11-1665-2018

Swiss Climate Change Scenarios 2018: A new climate-change scenario report has been published: external page CH2018

Swiss Climate Summer School 2017: Together with Stefan Brönnimann, Oliver Fuhrer, Olivia Martius, Christina Schnadt and Heini Wernli, I had the pleasure to organize the 16th Swiss Climate Summer School in external page Monte Verità, Ascona. The topic of the school was "High-resolution climate: observations, models and projections": Background information, presentations and pictures, external page previous Swiss Climate Summer Schools

High-resolution decade-long climate simulations over Europe: We have also conducted the first decade-long climate simuation over Europe with a computational resolution of 2 km: Leutwyler, D., D. Lüthi, N. Ban, O. Fuhrer and C. Schär, 2017: Evaluation of the Convection-Resolving Climate Modeling Approach on Continental Scales. J. Geophys. Res. Atmos., online, external page http://dx.doi.org/10.1002/2016JD026013

Other recent publications:

external page Schneider, T., J. Teixeira, C.S. Bretherton, F. Brient, K.G. Pressel, C. Schär, A.P. Siebesma, 2017: Climate Goals and Computing the Future of Clouds. Nature Climate Change, 7, 3–5, external page Abstract and download

Giorgi F., C. Torma, E. Coppola, N. Ban, C. Schär and S. Somot, 2016: Enhanced summer convective rainfall at Alpine high elevations in response to climate warming. Nature Geoscience. external page Abstract and download | Media: ETH News | external page NZZ

Schär, C., N. Ban, E. M. Fischer, J. Rajczak, J. Schmidli, C. Frei, F. Giorgi, T. R. Karl, E. J. Kendon, A. M. G. Klein Tank, P. A. O'Gorman, J. Sillmann, X. Zhang and F. W. Zwiers, 2016: Percentile indices for assessing changes in heavy precipitation events. Climatic Change. external page Abstract and download

Persische Hitzwelle, Sommer 2015: Die Kombination hoher Temperaturen und Feuchte hat es in sich: Denn sie macht das Klima für den Menschen bis 2100 in gewissen Regionen fast unerträglich – falls der Klimawandel nicht gebremst wird. Ein Beispiel war der Sommer 2015 im Persischen Golf, wie in einem external page News&Views Artikel in Nature Climate Change beschrieben. Dieser Artikel diskutiert eine external page Studie von Jeremy Pal and Elfatih Eltahir. Medien Artikel: external page Guardian | external page New York Times | external page Tages Anzeiger

Computing for Climate | Rechnen fürs Klima: ETH Zukunfts-Blog: English | Deutsch

Europäische Hitzewelle Sommer 2015: external page Hitzeblog (von Sven Kotlarski) | external page Interview Tages-Anzeiger