(Bloomberg Businessweek) -- In the Ferlo region of Senegal, climate change is making it harder for herders to find water for their cattle. In the Peruvian Amazon, indigenous tribes must remain alert at all times to chase off illegal loggers. In Los Angeles, city planners are struggling to figure out how best to plant 90,000 trees to help cool the hottest neighborhoods. To solve these problems, all three groups rely on a little-known ...