In the Panama Canal the grand challenges facing the world are played out in miniature. Here freshwater management, deforestation, biodiversity and global warming have converged to pose economic challenges that the rest of the world may not face for decades. From his perch in the middle of the rainforest, Biff Birmingham, director of the Smithsonian Tropical Research Institute (STRI), has made this convergence the focus of his research. He spoke at the Polly Hill Arboretum on Wednesday night.