URBan environments and Regional Climate Change (URB-RCC) – new CORDEX FPS on Urbanization

Cities play a fundamental role on climate at local to regional scales through modification of heat and moisture fluxes, as well as affecting local atmospheric chemistry and composition, alongside air-pollution dispersion. Vice versa, regional climate change impacts urban areas and is expected to increasingly affect cities and their citizens in the upcoming decades. Simultaneously, the share of the population living in urban areas is growing, and is projected to reach about 70% of the world population up to 2050. Thus, cities are becoming one of the most vulnerable environments under climate change. This is especially critical in connection to extreme events, for instance heat waves with extremely high temperatures exacerbated by the urban heat island effect, in particular during night-time, with significant consequences for human health.

This is clearly a problem of regional to local scales and local impacts, which cannot be addressed by GCMs and till now are not included commonly in regional simulations. Already in 2013, the CORDEX community identified cities to be one of the prime scientific challenges. Therefore, we proposed this topic to become an activity at CORDEX platform, within the framework of so called flagship pilot studies, which was accepted and the FPS URB-RCC activity has been started in May this year. The proposed activity relies on specific data, for the land-use parameterization and observations, which are available from previous campaigns, to perform the expected simulations and to validate them. This FPS action is connected to the certain extent to SDGs (Sustainable Development Goals) on sustainable cities (#11), climate action (#13) and health (#3), providing information for risk management in these aspects to urban stakeholders. Moreover, urbanization is important for many groups participating in CORDEX activities and goes across CORDEX domains as big cities appear in each of them. Clearly, careful selection of targeted coordinated simulations are going to be performed.

The main goal of this FPS is to understand the effect of urban areas on the regional climate, as well as the impact of regional climate change on cities, with the help of coordinated experiments with urbanized RCMs. While the urban climate with all the complex processes has been studied for decades, there is a significant gap to incorporate this knowledge into RCMs. This FPS aims to bridge this gap, leading the way to include urban parameterization schemes as a standard component in RCM simulations, especially at  high resolutions