Compound risks of droughts and heatwaves on water and energy systems

Ensuring reliable supplies of clean water and energy to a growing global population and under changing climate and extremes is an increasing challenge. The demands for both resources and their systemic interdependencies are particularly strong during droughts and heatwaves. Although research on the water–energy nexus has expanded in recent years, we still lack a fundamental understanding of how water–energy system processes propagate across time and space and may results in cascading impacts during extreme weather events. In addition, limited understanding exists on the trade-offs between management strategies and solutions designed to improve the supply of clean water and energy resources.

Here we will show compounds risks and impacts of climate change and extremes (i.e. droughts, heatwaves and compound events) on clean water and energy systems globally and discuss implications of management strategies to alleviate these risks on water–energy trade-offs. To quantify water and energy system processes in time and space, we developed new open access datasets and built new model frameworks integrating high spatiotemporal resolution models of hydrology, water quality, water use and energy systems.

Our results show that water use in the energy sector is substantially impacted by these hydroclimatic extreme events, with the strongest responses observed during heatwaves and compound drought–heatwave events¹. Future climate change is projected to reduce thermoelectric power plant usable capacity globally through rising surface water temperatures and increasing water scarcity². We found that declines in river flow during droughts over the last decades have to led to a 11% reduction in hydropower generation globally, using a hybrid physically-based and machine-learning model applied to our GloHydroRes global hydropower plant and reservoir dataset³.

Clean water scarcity intensifies across all sectors during these hydroclimatic extremes, due to reduced water availability, rising sectoral water demands, and deteriorating water quality⁴. While desalination and wastewater treatment and reuse are often promoted as key management strategies towards water scarcity alleviation, they come with substantial energy consumption, brine disposal challenges, and high costs. For instance, we quantified that desalination, wastewater treatment, and conventional drinking water treatment together account for up to ~5% of global electricity consumption, with strong regional variation⁵. In the Middle East, for example, desalination plants alone contribute to nearly one-fifth of total electricity use, largely powered by fossil fuels, resulting in tradeoffs with climate mitigation goals. This work is part of the B-WEX ERC project and will focus in a next step on developing joint clean water and energy transition pathways that remain robust under changing climate with increasing droughts, heatwaves, and compound events.

References

¹ Cárdenas Belleza, G.A., M.F.P. Bierkens, M.T.H. van Vliet (2023) Environ. Res. Lett. 18 104008, https://doi.org/10.1088/1748-9326/acf82e

² Jones, E.R. et al. (2025) Environmental Research: Water, 1, 2, 025002, https://10.1088/3033-4942/addffa

³ Shah, J. J. Hu, O.Y. Edelenbosch, M.T.H. van Vliet (2025) Scientific Data 12, 646, https://doi.org/10.1038/s41597-025-04975-0

⁴ van Vliet, M.T.H. (2023) Nature Water 1, 902–904, https://doi.org/10.1038/s44221-023-00158-6

⁵ Magni, M., E.R. Jones, M.F.P. Bierkens, M.T.H. van Vliet (2025) Water Research 277, 123245, https://doi.org/10.1016/j.watres.2025.123245