The record heat waves that scorched the earth from Arizona to Antarctica this year will only get worse, and cities, where heat radiates off buildings and asphalt, will bear the brunt of this heat. “We’ve built our cities like ovens,” Spotts says. “We’re largely using the same materials we have been using since World War II. We need a large-scale change.” According to NOAA, highly developed urban areas can experience mid-afternoon temperatures that are 15 to 20 degrees Fahrenheit warmer than surrounding, vegetated areas. Reducing greenhouse gas emissions tackles the root cause, but in the meantime, cities are looking for ways to lower the temperature. One of the cheapest is to paint roofs and streets white.
The Greek islanders of Santorini, with their whitewashed earthen buildings, were on to something: white surfaces can keep a densely populated area cooler. To this end, New York City has added white, reflective coatings to more than 10 million square feet of rooftop over the last decade. And Los Angeles has installed more than 30 million square feet of cool roofs as part of its new building code. These days, when you visit certain parts of L.A., such as Winnetka or Echo Park, you’ll notice the black asphalt changing to a light grayish-white on more than 50 city blocks.