Many people like these Tibetans in Qinghai, China, rely on indoor stoves for heating and cooking. That causes serious health problems. Courtesy of One Earth Designs hide caption

itoggle caption Courtesy of One Earth Designs

A man harvests fruits of the Jatropha tree in Taabo, Ivory Coast. Jatropha, which is grown in many parts of the world, has fallen from favor as a diesel fuel substitute. Kambou Sia/AFP/Getty Images hide caption

itoggle caption Kambou Sia/AFP/Getty Images