Journalist Sam Bloch used to live in Los Angeles. And while lots of people move to LA for the sun and the hot temperatures, Bloch noticed a real dark side to this idyllic weather: in many neighborhoods of the city, there's almost no shade. Shade can literally be a matter of life and death. Los Angeles, like most cities around the world, is heating up. And in dry, arid environments like LA, shade is perhaps the most important factor influencing human comfort. Without shade, the chance of mortality, illness, and heatstroke can go way up.