Adaptation should start with cities, because rising temperatures will have the biggest human health impact in urban environments. Cities are increasingly where we live, already accounting for more than half the world’s population, and by the end of the century the figure will be 80 to 90 percent. Moreover, cities are generally much hotter than surrounding countryside: they are filled with masses of nonreflective black surfaces that absorb the sun’s rays and lack green spaces and water features.
