How thermally comfortable are cities in the EMME region simulated to be in the future?

Urbanization significantly alters a region's land surface properties, which in turn modifies the surface energy balance, having an impact on the climate at the local, regional, and global levels. In particular, urban areas experience higher temperatures compared to their rural surroundings which in combination with humidity have an effect on the quality of the citizens’ lives. Wet-bulb temperature (WBT) is an essential and widely used metric to assess the effects of humid heat. A WBT of 35◦C is considered to be the survivability limit, and prolonged exposure beyond this value could be deadly even for the fittest of humans. The region of eastern Mediterranean and the Middle East (EMME) is highly susceptible to high WBT values, especially in densely populated areas, where humid heat events with WBT≥35◦ C are projected by the end of this century. It is therefore crucial to assess the projected levels of humid heat over this particular area.

This work uses the Weather Research and Forecasting (WRF) model to simulate climate over the EMME coupled with the bulk urban parametrization and NoahMP land surface scheme. The simulations are performed at 4 km horizontal resolution for a recent past (2000-2004) and a future (2056-2060) period driven by the Representative Concentration Pathway (RCP) RCP 8.5. The aim of this study is to investigate how the simulated minimum, minimum and wet bulb temperatures are projected to change in the future during the summer period over the EMME region and, more specifically, over eleven cities located in the region of interest. The simulated summer climatologies of the two periods of time of the maximum and minimum temperatures are derived from hourly timeseries, which are then to calculate the WBT using also the relative humidity by the model output.