Green roofs can help cool cities in the summer heat, but building them is only the first step – many don’t survive

The rooftop of the Javits Center in New York is still thriving, but others have struggled. Xinhua/Wang Lei via Getty Images

As summer temperatures soar across the United States and Europe, cities are being forced to confront the difficult reality that they’re getting dangerously hot.

Record-breaking heat waves strain power grids, send people to cooling shelters and can make the top floors of some apartment buildings unlivable.