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Last summer I packed my bags and left humid New York to spend a month reporting in the dry desert heat of Phoenix, Arizona. America’s fifth biggest city has always been hot, but day and night temperatures have been rising due to global heating and the city’s unchecked development, which has created a sprawling urban heat island that has literally become unliveable for some residents. In the past three years, 911 calls and emergency room visits for heat-related emergencies have skyrocketed and more than a thousand people have died from extreme heat. The city is scattered with cooling centres – air conditioned places where residents can go to cool down – but clearly this isn’t working for many people. I wanted to spend a good chunk of time in Phoenix to better understand why, and also who is most affected by the hotter days and nights.