Prof. em. Dr. Christoph Schär

Prof. em. Dr.  Christoph Schär

Prof. em. Dr. Christoph Schär

Professor Emeritus at the Department of Environmental Systems Science

ETH Zürich

Institut für Atmosphäre und Klima

CHN L 12.1

Universitätstrasse 16

8092 Zürich

Switzerland

Additional information

Honours

Year Distinction
2023 Vilhelm Bjerknes Medal, European Geosciences Union
2021 Highly Cited Researcher (Web of Science)
2021 Honorary doctorate of the University of Innsbruck, Austria
2018 Highly Cited Researcher (Web of Science)
2008 Honorary Professor at the Niels Bohr Institute, Univ. of Copenhagen (2008-2012)
1989 ETH Medal for PhD Dissertation

Farewell lecture

My farewell lecture took place on March 11, 2024. The recording (in German) can be viewed here.

Lectures | Vorlesungen

 

Swiss summer temperatures April-September

Animation illustrating the pronounced warming during the last decades (updated October 2022)

Animation Swiss Temperatures April-September

Legend: Swiss summer temperatures April-September (in blue: 1864-1992, in red: 1993-2022). The figure is based on the average temperature at four homogenized MeteoSwiss stations (Basel, Berne, Geneva and Zurich). The bell-shaped curves are Gaussian fits. The display represents an update from an earlier publication (Schär et al., 2004, external pageabstract and link).

More detailed description: englisch | deutsch

Download: Downloadanimated gif (GIF, 111 KB)

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 pagehttps://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 pagehttps://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 pagehttps://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 pagehttps://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 pagehttps://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 pagehttps://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 pagehttps://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 pagehttps://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 pagehttps://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 pagehttps://doi.org/10.5194/gmd-11-1665-2018

Swiss Climate Change Scenarios 2018: A new climate-change scenario report has been published: external pageCH2018

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 pageMonte Verità, Ascona. The topic of the school was "High-resolution climate: observations, models and projections": Background information, presentations and pictures, external pageprevious 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 pagehttp://dx.doi.org/10.1002/2016JD026013

Other recent publications:

external pageSchneider, 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 pageAbstract 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 pageAbstract and download | Media: ETH News | external pageNZZ

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 pageAbstract 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 pageNews&Views Artikel in Nature Climate Change beschrieben. Dieser Artikel diskutiert eine external pageStudie von Jeremy Pal and Elfatih Eltahir. Medien Artikel: external pageGuardian | external pageNew York Times | external pageTages Anzeiger

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

Europäische Hitzewelle Sommer 2015: external pageHitzeblog (von Sven Kotlarski) | external pageInterview Tages-Anzeiger

Convection-resolving climate modeling

Our group is leading a major modeling project funded by the Swiss National Science Foundation, entitled "convection-resolving climate modeling on future supercomputing platforms (crCLIM)". We are / were also part of several related EU projects (EUCP, CONSTRAIN) and have received grants for high-performance computing from PRACE.

Some earlier highlights

European and Alpine climate change studies:

  • Rajczak J. and C. Schär, 2017: Projections of future precipitation extremes over Europe: a multi-model assessment of climate simulations. J. Geophys. Res. Atmos., in press
  • Ban, N., J. Schmidli and C. Schär, 2015: Heavy precipitation in a changing climate: Does short-term summer precipitation increase faster? Geophys. Res. Letters., 42, 7889–7907, external pageAbstract and download
  • Kotlarski, S., D. Lüthi and C. Schär, 2015: The elevation dependency of 21st century European climate change: An RCM ensemble perspective. Int. J. Climatol., 35 (13), 3902–3920, external pagehttp://dx.doi.org/10.1002/joc.4254
  • Kotlarski, S., et al., 2014: Regional climate modeling on European scales: A joint standard evaluation of the EURO-CORDEX RCM ensemble. Geosci. Model Dev. Discuss., 7, 217-293, external pageAbstract and download
  • Rajczak, J., P. Pall, C. Schär, 2013: Projections of extreme precipitation events in regional climate simulations for Europe and the Alpine region. J. Geophys. Res, Vol 118 (9), 3610–3626, external pageAbstract and download

Swiss Climate Change Scenarios: We have been involved in the development of the recent Swiss Climate Change Scenarios (CH2011):
 

  • CH2011 (2011), Swiss Climate Change Scenarios CH2011, published by C2SM, MeteoSwiss, ETH, NCCR Climate, and OcCC. Zurich, Switzerland. 88 pp. ISBN: 978-3-033-03065-7

Objective calibration of climate models: Our group has developped a methodology for the objective calibration of regional climate models. The methodology is also used in the COSMO-CLM community and at MeteoSwiss. Key publications include:

  • Bellprat O., S. Kotlarski, D. Lüthi, C. Schär, 2012: Objective calibration of regional climate models. J. Geophys. Res., 117, Art. No . D23115, external pageAbstract and downlaod
  • Bellprat, O., S. Kotlarski, D. Lüthi, R. De Elìa, A. Frigon, R. Laprise, C. Schär, 2016: Objective calibration of regional climate models: Application over Europe and North America. J. Climate, 29, 819-838, external pageAbstract and download

Selected publication on European heat waves: Climate-change projections suggest that European summer heatwaves will become more frequent and severe during this century. Analysis of high-resolution regional climate simulations reveals consistent geographical patterns in these changes, with the most severe health impacts in southern European river basins and along the Mediterranean coasts:
 

  • Fischer, E.M. and C. Schär, 2010: Consistent geographical patterns of changes in high-impact European heatwaves. Nature Geoscience, Advance online publication, May 16, 2010 | doi:10.1038/ngeo866 | external pageAbstract and download | external pageNature news | ETH Life (Deutsch) | Klimablog Reto Knutti (Deutsch)contact | order pdf-file
  • Seneviratne, S.I., D. Lüthi, M. Litschi, and C. Schär, 2006: Land-atmosphere coupling and climate change in Europe. Nature443, 205-209. | Download: Article | Supplementary information | Nature Website: external pageAbstractexternal pageEditor's summary
  • Schär, C. and G. Jendritzky, 2004: Hot news from summer 2003. Nature,432, 559-560 | 
  • Schär, C., P.L. Vidale, D. Lüthi, C. Frei, C. Häberli, M. Liniger and C. Appenzeller, 2004: The role of increasing temperature variability in European summer heat waves. Nature,427, 332-336 |  | download PowerPoint-file | external pageranked by in-cites.com

Research interests

  • Climate dynamics, climate change and the water cycle
  • Atmospheric dynamics, flow past topography
  • Numerical methods in atmospheric and climate models
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