BBC: The world’s tropical forests face the double challenge of climate change and deforestation, says Andrew Mitchell. In this week’s Green Room, he explains why he is not giving up on the “impossible dream” of convincing governments that these trees are worth more alive than dead. Rumour has it that Brad Pitt is going into the Amazon. He will play out the story of an enigmatic explorer in search of his personal El Dorado. The explorer in question was Colonel Percy Fawcett, a …