*Watch Online/In person*Environmental change in the tropics is driving thousands of species to extinction. The tropics, the hotter, wetter zone around the equator, contain most of the world's species. This lecture explains why it is difficult to predict the number and identities of the most endangered species. It highlights what we know and can do to help stop some of the world’s most charismatic and unique species, such as the Geoffroy’s spider monkey and the hyacinth macaw, from going extinct.