Extreme Droughts in Mountain Regions: EMERGE

Effective mitigation and adaptation strategies to tackle extreme droughts in mountain regions rely on an understanding of their impacts and evolution. However, difficulties remain in gaining a complete picture of these events. First, while global databases of past droughts offer valuable insights into historical trends, these datasets often rely on coarse-resolution climate data and simplified characterisation techniques, failing to accurately capture how droughts have evolved in time and space. This limitation hinders our ability to effectively predict and prepare for future drought scenarios. 

Second, mountain regions present unique complexities for understanding and modeling droughts. Steep climatic and land-cover gradients, alongside intricate water storage systems – in the form of snow, glaciers, and groundwater – make these environments particularly challenging to analyze. The impacts of future droughts in these areas are expected to be severe, as warming temperatures lead to glacier retreat, shifts from snow to rain, groundwater depletion, and changes in mountain vegetation. Many current hydrological models fall short in accounting for the full range of climatic drivers, critical processes, and interactions between vegetation and hydrology, leaving significant gaps in our understanding of how past droughts unfolded in these sensitive regions. 

Finally, Switzerland faces an increasing likelihood of extreme droughts, especially during summer months. Yet, there is limited clarity on what these events might entail for water availability, vegetation responses, and potential tipping points. Ensuring stakeholders are adequately prepared for such scenarios requires a deeper understanding of potential future drought impacts that is specific to Switzerland. 

To address these interconnected challenges, the EMERGE project team is working on three key outputs:   

1. A New Global Database of Past Extreme Droughts 
   EMERGE is creating a high-resolution global database of historic megadroughts, using novel climate downscaling and drought characterization techniques to map how these events evolved. This database, which includes detailed data from mountain regions, will be invaluable for understanding and predicting drought trends and impacts.
    

2. Simulating Recent Droughts in Mountain Regions 
   The project employs an advanced ecohydrological model to simulate how recent extreme droughts have affected water fluxes in Switzerland and the Andes of central Chile. This work will deepen our understanding of how water is stored and moved in mountain regions during droughts, enabling better water management strategies. 
    

3. Stress-Testing Switzerland’s Future 
   EMERGE is downscaling global climate model-generated ‘storylines’ of potential future extreme droughts in Switzerland, and simulating these droughts using a state-of-the-art ecohydrological model to test the resilience of Switzerland’s mountain systems.  

By investigating extreme droughts in mountain regions in this way, the EMERGE project aims to uncover insights that can improve our understanding of the mechanisms driving these events and their cascading impacts. This knowledge will support effective mitigation and adaptation measures to safeguard water resources and ecosystems, building resilience in the face of an uncertain climate future. 

The EMERGE project is part of WSL’s Extremes Research Program, which runs until the end of 2025 and aims to equip Swiss stakeholders with the resources needed to meet the challenges of future extreme events.  

Building on work from EMERGE, the Water4All project MegaWat (running 2024-2026) aims to advance scientific understanding of potential megadroughts in Europe’s mountains and provide advanced information and tools to respond.