EMERGE
Extreme droughts in mountain regions: consequences for blue-green water fluxes.
About the project
As the climate warms, mountain regions are increasingly likely to experience extreme droughts, with potentially far-reaching consequences for downstream ecosystems and communities. Despite the seriousness of this threat, our knowledge of when and where extreme droughts have occurred, and of how extreme droughts develop in mountain regions, remains limited.
To address this knowledge gap, EMERGE has three main aims: 1) To make a new high-resolution global database (including mountain regions) of past extreme droughts using novel climate downscaling and drought characterisation techniques, and to use this database to explore extreme drought trends and impacts on vegetation. 2) To simulate recent extreme droughts in Switzerland and the Andes of central Chile using a state-of-the-art ecohydrological model, and to use these simulations to develop a new understanding of the partitioning of blue and green water fluxes in mountain regions during these events. 3) To downscale global climate model-generated storylines of potential future extreme droughts in Switzerland; and to simulate these droughts, again using a state-of-the-art ecohydrological model, to test the resilience of Switzerland’s mountain systems to such events.
FUNDING: WSL Extremes
PERIOD: 2022-2025
What have we found?
How have multi-year droughts changed around the world in the recent past?
In our recent study, we used the drought index SPEI, calculated from CHELSA climate data, in a mathematical morphology approach to generate a new global database of multi-year droughts since the 1980s, at 5-km resolution. We found that droughts have become bigger, drier and hotter, and that they’ve had an increasingly negative impact on vegetation greenness.
Temperate grasslands have been more affected by multi-year droughts than tropical and boreal forests, and the global land area affected by multi-year droughts has increased by roughly the size of Switzerland each year. We hope our results will encourage increased preparedness for future such extreme events. https://www.science.org/doi/10.1126/science.ado4245
