 The rays of the sun go right in and warm up the surface. So in a city, the best thing to do, yes, plant trees. That's good. It's good for human health. It's good for the aesthetics. It's good for the temperature on the street level. But you can paint roofs white. And there's several different products in effect right now that you can do to paint your roof white. And it'll not only help reduce some of the warming in the city, it'll help your energy bill as well.