GlobalPost: Officials here frequently claim that the huge hydroelectric dams that increasingly dot the Brazilian Amazon are a source of "clean energy.' The dams often flood vast areas of rain forest, leading to a major loss of biodiversity and the devastating displacement of indigenous communities from their ancestral lands. That is justified, President Dilma Rousseff claims, because they help fight climate change. "[Hydroelectric power] does not emit greenhouse gases, and that means we have a renewable energy...