Urban cities are hot. They are full of heat-trapping tar, pavements and dark surfaces that absorb heat and increase ambient temperatures. This is called the Heat Island Effect and is responsible for increased urban temperatures compared to adjoining suburban areas. According to the EPA- black surfaces in the sun can become up to 70°F hotter than the most reflective white surfaces. The effects of the Urban Heat Island are obvious- higher energy use to cool this excess heat that leads to higher stress on the power grid and increased pollution. On a clear night, the temperature in a city with 1 million people or more can be up to 22°F hotter than nearby suburbs. One initiative in New York City is helping cool it down- by painting roofs white!