Background
What is the goal of this WebApp?
Target audience
Scientifically sound, easy to understand, and with a pinch of humour: this WebApp is aimed at those with a personal or professional interest, at teachers and school classes, and at the curious and brave who want to learn more about the impacts of climate change on Switzerland.
In particular, it speaks to the impatient, who prefer their facts in small, digestible portions; to the intrepid, who aren’t afraid of complexity; and to those who want to take the future into their own hands – today.
What is presented?
Using three different extreme climate scenarios of increasing severity, the WebApp shows what impacts heatwaves, prolonged droughts, and extreme rainfall could have on the environment and society in Switzerland; what interactions and chain reactions these impacts can trigger; and what measures and solutions already exist – or are currently being developed by researchers – to deal with extreme events.
What isn't presented?
A handful of topics, such as peatlands and grasslands, as well as changes in energy production, or the impact of adaptation measures – on agriculture, for example and many other possible solutions and measures.
Some of the connections between the areas presented, so users don’t get lost in the complexity.
This is just a first selection!
What’s behind the climate scenarios?
The Extremes WebApp considers three levels of climate extremes. All three levels describe the near future – the next 20 years. The more extreme the 'extreme', the lower the probability of the scenario. Nevertheless it is physically consistent for levels 1 to 3 and therefore well within the realm of possibility. Levels 0 and 4 are not physical scenarios and are included purely for entertainment purposes.
Level 1:
The extremes shown in Level 1 broadly correspond to the extreme events of the past 10-15 years, such as the severe droughts of 2003 or 2018-2020. In other words, these are extremes that are no longer all that extreme, because they have occurred repeatedly or with increasing frequency in recent years.
Level 2:
At this level, extreme events are shown as they appear in the official climate scenarios for Switzerland (CH2018) up to around 2040. These scenarios therefore do not describe average conditions, but rather the more extreme climate that occurs occasionally in several models in the near future. The impacts of such climate events have been calculated or derived in numerous studies. They are summarised at this level.
Level 3:
The most extreme level is represented by scenarios that are relatively unlikely, but physically plausible. These are calculated using climate models that are deliberately pushed towards extreme conditions. This generates scenarios that broadly correspond to the once-in-a-century events that occurred in California between 2011 and 2015, or in Chile over the past 10–15 years. Such events do occur, but not very often – their consequences, however, can be severe. Due to a lack of suitable data, the impacts of these climate events have not yet been fully modelled. Progress is currently being made in this area. The impacts described here have been extrapolated to Switzerland based on observations and studies from other regions. As a result, they are less certain than the impacts described in Level 2.
How are future extreme events studied?
Two different methods are commonly used to study extreme events.
The first is known as “space-for-time substitution”. Instead of waiting locally – for example in Switzerland – for extreme events to occur frequently enough to build sufficiently large datasets for analysis, researchers study extreme events elsewhere. Around the world, extreme events such as prolonged droughts occur repeatedly and with increasing frequency. By studying these events where they occur, many extreme events can be compiled and analysed in a short period of time, and general rules can be derived (Chen et al. 2025). Not all events identified in this way are typical for Switzerland. However, there are many events in other regions of the world that are similar, and therefore relevant, to Switzerland.
The second approach is based on model simulations. To be realistic, these simulations must correctly represent the chain of effects from cause to impact. Science has developed many suitable models, ranging from global to regional climate models, which can produce different projections of future climate conditions. A further step is taken by impact models, which simulate the effects of such climatic extremes on the environment and society and therefore require extreme input data. Generating plausible datasets for climate extremes in specific regions is highly challenging, as these datasets must be physically consistent and include an approximate probability of occurrence. Such datasets can, for example, be extracted from the vast archives of climate model data used as the basis for IPCC reports (e.g. IPCC 2023). Because these archives do not always provide the extremes typical for a given region, it has recently become possible to simulate extreme climate events in a targeted way (Gessner et al. 2022, 2023; Fischer et al. 2023). These simulated extreme events can then be used in models to calculate their impacts.
References:
Chen L., Brun P., Buri P., Fatichi S., Gessler A., McCarthy M.J., Pellicciotti F., Stocker B., Karger D.N. (2025) Global increase in the occurrence and impact of multiyear droughts. Science Vol. 387 (6731): 278-284. DOI: 10.1126/science.ado4245
Fischer E.M., Beyerle U., Bloin-Wibe L., Gessner C., Humphrey V., Lehner F., Pendergrass A.G., Sippel S., Zeder J., Knutti R. (2023). Storylines for unprecedented heatwaves based on ensemble boosting. Nature Communications 14(1):4643.
Gessner C., Fischer E.M., Beyerle U., Knutti R. (2023) Developing Low‐Likelihood Climate Storylines for Extreme Precipitation Over Central Europe. Earth's Future 11(9): e2023EF003628.
Gessner C., Fischer E.M., Beyerle U., Knutti R. (2022) Multi-year drought storylines for Europe and North America from an iteratively perturbed global climate model. Weather and Climate Extremes 1;38:100512.
Intergovernmental Panel on Climate Change IPCC (2023). Summary for Policymakers. In: Climate Change 2023: Synthesis Report. Contribution of Working Groups I, II and III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. IPCC, Geneva, Switzerland, pp. 1-34, doi: 10.59327/IPCC/AR6-9789291691647.001
What’s behind the WebApp?
The Extremes WebApp was developed as part of the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) Extremes Research Programme (2020–2025). The Extremes Research Programme focuses on extreme events and the development of solution-oriented approaches in collaboration with non-academic partners.
The EMERGE project characterises mega-droughts worldwide in order to identify trends and delineate how prolonged, multi-year droughts could develop in Europe and Switzerland.
The ExtremeThaw project investigates the impact of climate warming on the distribution of permafrost in Switzerland, and looks at the associated potential release of pollutants, as well as the effects on high-alpine vegetation and the carbon balance in mountainous regions.
The MountEx project develops digital decision-support tools for forward-looking forest management in mountain regions. In these regions, protection forests safeguard against natural hazards – but are themselves increasingly affected by climate change.
Building on an existing drought-warning platform, the MaLeFiX project is developing additional 30-day forecasts for bark beetle populations, forest fire risk, watercourse temperatures, groundwater levels, and more. Such forecasts support decision-making and planning.
In collaboration with a local energy provider, the ALANex project investigates the effects of light pollution on nocturnal insects in order to derive recommendations for public lighting.
Who contributed to the WebApp?
The WebApp was made possible through the financial support of the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL). In addition to the Extremes Research Programme and its project collaborators, the following contributors were responsible for developing the content:
Astrid Björnsen
Niklaus Zimmermann
Kontakt: extremesprogram@wsl.ch
Concept development, visual design, programming, and translating scientific content into digestible chunks was the work of Zense GmbH
Marion Deichmann, Projectlead and Animation
Madleina Dörig, Illustration and Screendesign
Sven Langone, Animation
Mirko Lemme, Programming
Yves Erne, Art Direction
with the support of the Zense-Team.
Technical Support:
Christian Wessalowski and Wei Li, WSL IT.
Reference:
Astrid Björnsen, Marion Deichmann, Madleina Dörig, Peter Bebi, Pierluigi Calanca, Martin Gossner, Dirk N. Karger, Petia Nikolova, Tobias Wechsler, Massimiliano Zappa, Niklaus E. Zimmermann (2025). How Will Switzerland’s Climate Look in Future? WebApp.
The WebApp is Open Access. All texts and illustrations are licensed under the Creative Commons Attribution 4.0 International (CC BY 4.0) licence. They may be freely reproduced, distributed, and adapted, provided the source is acknowledged.
WSL accepts no liability for any damage resulting from the application or use of the WebApp.
topics pages
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Climate Change
.+4 °C and beyond: Swiss landscapes under climate change. Link
Climate ChangeReferences:
Climate impact of CO₂:
Etminan M. et al. (2016) Radiative forcing of carbon dioxide, methane, and nitrous oxide: A significant revision of the methane radiative forcing. Geophysical Research Letters 43(24): 12614-12623. LinkRelationship between CO₂ and temperature
Arrhenius, S. (1896). On the Influence of Carbonic Acid in the Air upon the Temperature of the Ground. Philosophical Magazine and Journal of Science, 41, 237–276.
Callendar G.S. (1938). The artificial production of carbon dioxide and its influence on temperature. Quarterly Journal of the Royal Meteorological Society. LinkTemperature rise and industrialisation:
Hansen J et al (2006) Global temperature change. PNAS 103(39): 14288-14293. LinkImpacts of global temperature rise:
IPCC, 2022. Climate Change 2022: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press. LinkRegional impacts:
IPCC (2022) Summary for Policymakers. Pörtner H.O. et al.(eds.)]. In: Climate Change 2022: Impacts, Adaptation, and Vulnerability. Contribution of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, UK and New York, NY, USA, pp. 3-33, doi:10.1017/9781009325844.001. Link
Federal Office for the Environment (2025). Climate Risk Analysis for Switzerland: Basis for Adaptation to Climate Change. Umwelt-Wissen series, Bern. LinkTemperature change and economic production:
Burke, M. et al. (2015) Global non-linear effect of temperature on economic production. Nature 527, 235–239. LinkClimate change in Switzerland
https://www.meteoswiss.admin.ch/climate/climate-change.htmlKyoto Protocol reduction targets (Switzerland’s target in Annex B): Link
Feedbacks and tipping points:
Steffen W. et al. (2018) Trajectories of the Earth System in the Anthropocene. PNAS 115(33): 8252-8259. Link -
Heavy Precipitation
Swiss Climate Scenarios CH2018: Heavy precipitation Link
Heavy PrecipitationReference:
Peleg, N., Koukoula, M., Marra F. (2025). A 2°C warming can double the frequency of extreme summer downpours in the Alps. npj Climate and Atmospheric Science 8: 216. Link -
Drought
Since the wake-up call of the hot and dry summer of 2003, Switzerland has engaged intensively with the issue of drought. More than 20 years later, research – and subsequent events – have confirmed that even the 'water tower of Europe,' the Alps, can be affected by extreme drought. Global studies also point to the growing risk of multi-year droughts, which could have consequences for the environment and society that are still difficult to imagine today. Switzerland is not unprepared, however: since 2012, research institutions and public authorities have been working closely together to improve preparedness for future drought events.
Further information: Conference proceedings, pp. 13, 73, 87
DroughtReference:
Zappa M., Karger D.N., Hüsler F. (2025) Extreme drought in Switzerland: Regional and local perspectives of a global challenge. In: Björnsen A. (Ed.) Forum for Knowledge 2025: Extremes. WSL Ber. 164, 13-21. Link -
Heat
Heatwaves pose a major global challenge, not least because these extreme events have serious impacts on human health. Due to climate change, the intensity, duration, and frequency of heatwaves have increased significantly in most regions of the world. Climate model simulations project that further increases in greenhouse gas concentrations in the atmosphere will make such extremes even more likely. Forecasting can help to warn vulnerable groups and affected sectors at an early stage, allowing appropriate measures to be taken.
Further information: Conference proceedings, pp. 23 and 31
HeatMore about research:
Domeisen, D.I.V. (2025). Heatwaves in a changing climate: How well prepared are we? In: Björnsen, A., Zimmermann, N. (Eds.), Forum for Knowledge 2025: Extremes. WSL Reports 164, 23–30. LinkMore about practise:
Huber, N. (2025). Impacts of Heat on Health. In: Björnsen, A. (Ed.), Forum for Knowledge 2025: Extremes. WSL Reports 164, 31–34. Link -
Glacier Retreat
Why Glaciers Matter – And What Research Is Doing. Video with Daniel Farinotti, WSL
Glaciers in Switzerland (2025): Factsheet (PDF)
Glacier RetreatReferences:
Ayala, A., Farinotti, D., Stoffel, M., & Huss, M. (2020). Glaciers: Hydro-CH2018 synthesis report chapters:“future changes in hydrology “. ETH Zurich.
Farinotti, D., Pistocchi, A., & Huss, M. (2016). From dwindling ice to headwater lakes: could dams replace glaciers in the European Alps?. Environmental Research Letters, 11(5), 054022. Link
Huss, M., & Hock, R. (2018). Global-scale hydrological response to future glacier mass loss. Nature Climate Change, 8(2), 135-140. Link
Linsbauer, A., Huss, M., Hodel, E., Bauder, A., Fischer, M., Weidmann, Y., ... & Schmassmann, E. (2021). The New Swiss Glacier Inventory SGI2016: from a topographical to a glaciological dataset. Frontiers in Earth Science, 9, 704189. Link
Stahl K., Weiler M., Kohn I., Freudiger D., Seibert J., Vis M., Gerlinger K. 2017: The snow and glacier melt components of streamflow of the river Rhine and its tributaries considering the influence of climate change. Final report to the International Commission for the Hydrology of the Rhine basin (CHR). English version. Report CHR 00-03 2017. Link
Zekollari, H., Huss, M., & Farinotti, D. (2019). Modelling the future evolution of glaciers in the European Alps under the EURO-CORDEX RCM ensemble. The Cryosphere, 13(4), 1125-1146. Link -
Permafrost
Changes in alpine permafrost usually occur out of sight, yet they have important consequences for mountain regions. Over the past decade, permafrost temperatures in the Swiss Alps have risen by up to 1 °C, and the thaw layers have thickened by several metres. At the same time, the ice content in the ground has decreased, and rock glaciers have been moving downslope faster than at the beginning of monitoring more than 20 years ago. These substantial changes below the surface threaten high-mountain infrastructure and lead to an increase in natural hazards such as rockfalls and debris flows.
Further information: Conference proceedings, p. 35
PermafrostReference:
Nötzli, J., Peter, A., Hählen, N., & Phillips, M. (2025). Hidden ice in the Swiss Alps: Permafrost is thawing ever faster. In: Björnsen, A. (Ed.), Forum for Knowledge 2025: Extremes. WSL Reports 164, 35–47. Link -
Gravitational Natural Hazards
WSL Magazine DIAGONAL 1/25 on Climate Change and Natural Hazards: Link
WSL Research Programme Climate Change and Alpine Mass Movements (CCAMM) 2018–2025: Link and News WSL
Gravitational Natural HazardsReferences:
Bettzieche, J. (2024). More wet, less dry: The avalanches of the future. WSL News, 6 November 2024. Link
Bettzieche, J. (2024). Climate change leads to more alpine hazards. WSL News, 31 October 2024. Link
Swiss Federal Institute for Forest, Snow and Landscape Research WSL (2025). Stop! Danger! Climate change and natural hazards. WSL Magazine Diagonal, 2025/1: 36 pp. Link
Jacquemart M., Weber S., Chiarle M., Chmiel M., … & Markus Stoffel (2024). Detecting the impact of climate change on alpine mass movements in observational records from the European Alps. Earth-Science Reviews 258:104886. Link
Naturgefahrenportal des Bundes: https://www.naturgefahren.ch
Walter et al. (2020) Direct observations of a three million cubic meter rock-slope collapse with almost immediate initiation of ensuing debris flows. Gemorphology 351, 1069333. Link -
Water Balance
Water BalanceReferences:
Swiss Federal Office for the Environment (FOEN) (2021). Impacts of climate change on Swiss waters. NCCS Hydro-CH2018. Environmental Knowledge Series. 134 pp. Synthesis report and brochure. Synthesebericht und Broschüre.
Federal Office for the Environment (FOEN) (2023). Heat and drought in summer 2022. Dossier
Brunner et al. (2019). Contribution of water reservoirs to reducing future water scarcity? Wasser Energie Luft, 111(3), 145–152. Link
Compagno et al. (2021). Brief communication: Do 1.0, 1.5, or 2.0 °C matter for the future evolution of Alpine glaciers? The Cryosphere 15(6). https://tc.copernicus.org/articles/15/2593/2021/
Lanz et al. (2021). Impacts of climate change on water management in Switzerland. Beiträge zur Hydrologie der Schweiz, Bern. Link
Padrón, R. S., Zappa, M., Bernhard, L., & Bogner, K. (2025). Extended-range forecasting of stream water temperature with deep-learning models. Hydrology and Earth System Sciences, 29(6), 1685-1702. Link -
Tree Vitality
Tree VitalityDrought & beech. Video on WSL research.
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Agriculture
AgricultureReferences:
Recommendations for climate adaptation:
Agroscope dossier “Climate change challenge" Link
Wuyts et al. (2023). Climate-resilient arable farming 2035. Agroscope Science 177, 197 pp. Link
Heinz et al. (2024) How to find alternative crops for climate-resilient regional food production. Agricultural Systems 213 (103793). LinkImpacts of drought and CO₂:
Holzkaemper, A., & Calanca, P. (2022). Impacts of the drought years 1947, 2003 and 2018 on agriculture. In: Hot and dry summers in Switzerland. Geographica Bernensia, Bern, 16–17. Link
Webber et al. (2018). Diverging importance of drought stress for maize and winter wheat in Europe. Nature Communications 9 (4249). LinkSoil moisture: measurements and forecasts
www.bodenmessnetz.ch
www.bodenfeuchte-ostschweiz.ch (Eastern Switzerland)
www.oasi.ti.ch/web/dati/suolo.html (Southern Alps) -
Biodiversity
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Fish Mortality and Species Extinction
Why is heat problematic for fish? SRF Kids News video Link
Fish Mortality and Species ExtinctionReference
Bonaglia A, Shen C, Padrón R, Bogner K, Fopp F, Rubin A, Rubin JF, Adde A, Guisan A, Albouy C, Pellissier L (2025). Sub-seasonal forecasting of thermal stress for Swiss river fishes during heatwaves. Ecological Modelling 507, 111171. Link
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Energy Production
Energy ProductionReferences:
Federal Department of the Environment, Transport, Energy and Communications (DETEC) (2021). Joint declaration of the Round Table on Hydropower. Minutes of 21 June 2021. Link
Micocci, D., Bragalli, C., Toth, E., Wechsler, T., Zappa., M. (2025). Hybridization of an Alpine pumped-storage hydropower plant with floating solar photovoltaics: a study from the water resource perspective. Renewable Energy. Link
Otero et al. (2023). Impacts of hot-dry conditions on hydropower production in Switzerland. Env. Res. Letters 18(6): 064038. Link
Stecher G, Herrnegger M (2022) Impact of hydropower reservoirs on floods: evidence from large river basins in Austria. Hydrological Sciences Journal 67(14). Link -
Loss of Protection Forests
The increasing frequency of extreme disturbance events such as bark beetle infestations and windthrow in the context of climate change poses major challenges for forest management in Switzerland. Particularly affected are spruce-dominated mountain forests, which are widespread and often fulfil a key protective function against natural hazards. WSL is working together with practitioners to develop a basis for prioritising the management of these forests under the influence of extreme disturbances. To this end, spatial data on forest structure, site conditions, disturbance susceptibility, and natural hazards are linked at landscape scale with silvicultural, planning, and economic aspects, and visualised in an interactive dashboard.
Loss of Protection ForestsReferences:
Bont LG, Blatter C, Rath L, Schweier J (2025). Automatic detection of forest management units to optimally coordinate planning and operations in forest enterprises. Journal of Environmental Management 372: 123276. Link
Hobi, M., Brandes, T., Bebi, P., Helzel, K., Bottero, A., Bührle, L., … (2025). Management of spruce-dominated mountain forests in the context of extreme disturbances. In: Björnsen, A., Zimmermann, N. (Eds.), Forum for Knowledge 2025: Extremes. WSL Reports 164, 49–59. Link
WSL (2023). Interim results of the 5th National Forest Inventory (NFI). Swiss forests are suffering under weather extremes. Media release, 30 May 2023. Link -
Forest Fires
When, where, how often, why, and how intensely forests burn depends on many factors. In the short term, forest fire risk is primarily influenced by extreme drought, often combined with high temperatures or strong winds that make combustible material more flammable. In the long term, land use and population pressure are decisive factors alongside climate change. The decline of traditional agriculture in rural regions and the more frequent occurrence of prolonged droughts in recent years point to a possible intensification of the phenomenon.
Forest FiresReferenz:
Pezzatti, G.B., Conedera, M., Ferriroli, D., Ghiringhelli, A., Ballmer, M., & Beyeler, S. (2025). Forest fires under climate change: Is Switzerland prepared? In: Björnsen, A., Zimmermann, N. (Eds.), Forum for Knowledge 2025: Extremes. WSL Reports 164, 61–72. Link
Carbon release after forest fires:
Santín C. et al. (2016) Towards a global assessment of pyrogenic carbon from vegetation fires. Global Change Biology 22(1): 76-91. Link -
Bark Beetle
Bark BeetleBark Beetle at WSL (Website)
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CO₂ Balance