EGU 2025: Understanding and Adapting under Deep Uncertainty

Many sessions were of direct (e.g. hydrological sciences) or indirect (e.g. climate) interest in the context of water research. Our changing climate, growing world population, an developing economies put continuing and mostly increasing stress on the waters that we need to sustain ourselves, produce our food, etc. Analyses and projections of droughts, floods, and water quality issues, but also approaches for mitigation and adaption, were central in many presentations. Some initiatives work to bring together actionable insights and information, such as the World Drought Atlas that guides management of and adaptation to drought and support policy actions, and the Planetary Health Check that is the most comprehensive, science-based global initiative dedicated to measuring and maintaining the Earth system.

Droughts imply insufficient water (quantity, quality) to meet needs (human, agriculture, nature,…); heatwaves may contribute to droughts through decreasing availability and driving demand increase. From that perspective, the following insights are sobering:

• Overshooting the Paris Agreement 1.5 degrees temperature increase objective seems unavoidable now.
• Atmospheric methane, a strong greenhouse gas, is on the rise since (again) since the 2000s. This is not (primarily) caused by fossil extraction and consumption, but originates from biological sources: agriculture and wetlands. The former may be managed to some degree, the latter are largely out of our control.
• Europe is one of the global heatwave hotspots in our warming climate, even when we eventually manage to stabilize our climate with net-zero emissions. Advection of hot air from neighboring regions is the primary mechanism for their generation.
• However, AMOC collapse scenarios with cooling & drying of Europe are also still on the table.

Understanding these challenges and their implications for our societies and how we relate to water is crucial, but so is recognizing the inherent uncertainties in the projections of future climate extremes and water availability. Not in the least because the transition of our global society towards a greener version is subject to many uncertain and unpredictable developments. Therefore, more than ever, methods for making decisions under increasingly uncertain conditions become important. I am happy to be contributing to the session on Decision Making Under Deep Uncertainty for Planning Water Systems Adaptation to Global Change, just before my return home. I cannot wait to start introducing all new ideas and insights into our research at KWR.

Image 1: EGU General Assembly 2025