Urban warming and global warming: Combined effect on thermal discomfort in the desert city of Beer Sheva, Israel

•Studies examine the effect of global and urban warming focusing on temperate areas.•We examine the combined effect of global and urban warming on human heat stress.•In desert city vegetation can increase air humidity, which aggravates heat stress.•Universal indices most appropriate for evaluating thermal stress in desert cities.

The effect of climatic changes on human comfort levels was investigated through examination and statistical analysis of long-term trends in human discomfort during summer months in the desert city of Beer Sheva, Israel and in the adjacent rural area of Wadi Hatzerim. In an era of global warming, the urban warming effect is likely to be amplified and as a result increase human discomfort, especially during summer.Climate data for the city of Beer Sheva over the last 40 years shows an increase of temperature and air humidity in comparison to the surrounding rural area. Wind velocity data for Wadi Hatzerim show that changes are inconstant and not significant, while in Beer Sheva, wind velocity is significantly reduced. Two indices – the Discomfort Index (DI) and Physiological Equivalent Air temperature (PET) – were used to evaluate the effect of these climatic changes on human discomfort. Although the bio-meteorological indices showed the same tendency of increasing heat stress values and duration, in Beer Sheva they were more pronounced and more significant than in the desert environment. The study concludes that these combined climatic effects negatively impact human comfort and are more noticeable in desert cities at peak daytime hours during summer.