It's one of the most fashionable ideas to save the planet from global warming: buying up tropical rainforest to save it from destruction. Gordon Brown has even appointed the millionaire founder of one such charity, Johan Eliasch, as his special adviser on deforestation. But like all big ideas it is controversial, and this week a leading Amazonian campaigner will visit Britain to protest that this latest trend is linked to a health and social crisis among indigenous people, including sickness, depression, suicide, obesity and drug addiction. Davi Kopenawa, a shaman of the Yanomami tribe, will help launch a report that,...