Riyadh (Saudi Arabia Mohamed Hussain Younis) / EyeEm/ Getty Images
Over the past 40 years, extreme heat has presented a greater challenge to urban populations than it has for rural ones.
Cities are more vulnerable to heat due to climate change as well as the urban heat island effect, a phenomenon in which urban areas are hotter than rural areas because of their higher concentrations of human activity and built infrastructure.
Cascade Tuholske, University of California Santa Barbara and his associates used global urban population data together with global fine resolution maximum air temperature.
