Improved models, improved information? Exploring how climate change impacts pollen, influenza, and mold in Berlin and its surroundings

Urban decision makers rely on evidence-based climate information tailored to their needs to adequately adapt and prepare for future climate change impacts. Regional climate models, with grid sizes between 10–50 km, are a useful outset to understand potential future climate change impacts in urban regions. Recently developed convection-permitting climate models have grid sizes smaller than 5 km, and better resolve atmospheric processes related to the land surface like convection, and complex terrain such as cities. This study investigates how the convection-permitting model REMO simulates changes in climate conditions in the urban-rural context, compared to its conventional hydrostatic version. We analyze three impact cases: influenza spread and survival; ragweed pollen dispersion; and indoor mold growth. Simulations are analyzed for the near future (2041–2050) under emission scenario RCP8.5. Taking the Berlin region as a testbed, we show that the change signal (positive or negative impact) reverses for the 3 km compared to the 12.5 km grid resolution for the impact cases pollen, and mold, indicating added value. For influenza, the convection-permitting resolution intensifies the decrease of influenza days under climate change. The results show the potential of convection-permitting simulations to generate improved information about climate change impacts for urban regions to support decision making.