Persistent hot and dry summer extremes bring elevated societal risks, relevant to many different sectors, such as human health, ecology (wildfires, water management), agriculture (crop losses), the energy sector, infrastructure and economy. The dynamical drivers of such extremes and their evolution under future climate change scenarios remain poorly understood and are often underestimated in models. An underestimation of future risks from heat and drought in model projections could be consequential for developing adequate adaptation measures necessary to prevent most severe impacts. PERSEVERE will provide necessary insights to better understand the effects of anthropogenic climate change on mid-latitude summer circulation and predict persistent hot and dry extremes, contributing to a more comprehensive knowledge base for decision support. In climXtreme 1, we found that double jet stream states have doubled in frequency in the past 4 decades, driven by an increase in persistence (Rousi et al., 2022). This increase has important implications for western European heatwaves, such as the 2018 summer extreme heat and drought event (Rousi, Fink et al., 2023). Such spatially compound extremes that affect large parts of Europe and/or the mid-latitudes can bring increased risks and contemporaneous system failures (Kornhuber et al., 2020; Di Capua et al., 2021).

In climXtreme 2, PERSEVERE will continue the work towards understanding the role of climate change in altering large-scale drivers of summer extremes in Europe using climate model data. According to IPCC (2021) there is low confidence in how dynamic changes have affected and will affect the location and magnitude of extreme events, while there is evidence that dynamical changes and their surface imprints may be more important than what suggested by existing climate models (Luo et al., 2021, Kornhuber et al. 2023). This is why more studies on the links of atmospheric dynamics and extremes are necessary to reduce the uncertainties in their prediction and future projections. Therefore, we will continue to investigate how double jets and their impacts on surface weather are represented in models and how they are projected to change under different anthropogenic climate change scenarios. In summary, building on our previous work and incorporating expertise from our partners from the climXtreme network, to which we have actively contributed, we aspire to tackle uncertainties in the changing frequency and intensity of European extremes under different climate change scenarios that are related to dynamical changes in the atmosphere. Comparing different climate model simulations and observations we will be able to quantify the contribution of human induced changes versus natural variability in large-scale circulation and jet stream states.

Website: PERSEVERE

Institution: Potsdam Institute for Climate Impact Research (PIK)¹, Vrije Universiteit Amsterdam and Royal Netherlands
Meteorological Institute (KNMI)²

Contact: Dr. Efi Rousi¹, Dr. Kai Kornhuber¹, Prof. Dim Coumou²