Heat Stress under Urbanization and the Mitigating Effect of Urban Greening - A Sensitivity Study for the 2019 European Heat Wave

Abstract:

Understanding the effects of urban environments on weather and climate is crucial to estimate the impact of climate change on society and economy especially under the ongoing process of urbanization. These interactions become even more important when considering the characteristics of extreme events such as heat waves.

This study aims to investigate the changes in heat stress in metropolitan areas given different urbanization and/or greening scenarios. In order to quantify the differences of these scenarios, we employ the NWP model ICON-LAM (ICOsahedral Nonhydrostatic Model in Limited Area Mode) at convection permitting horizontal resolutions of 1 km and 500 meters. Our one-month experiment comprises the 2019 ``record breaking'' heat wave in Western Europe.

We conduct a sensitivity study for (1) urbanization and (2) urban greening, for each horizontal resolution. In particular, we apply current and artificially enlarged urban land use cover to simulate progressing urbanization. An urban greening approximation is introduced into the simulations by increasing the vegetative land use fraction within the urban area.

Our analysis focuses on identifying the effects of urbanization on heat stress under extreme heat wave conditions for various metropolitan areas and the corresponding socio-economic impact (e.g., public health, productivity). Further, we quantify effects of urban greening as an efficient tool to mitigate expected climate change impacts especially under the ongoing urbanization conditions.