US actor Leonardo DiCaprio (L) and Paris mayor Anne Hidalgo pose as they arrive for the Paris premiere of the documentary film "Before the Flood" on October 17, 2016 in Paris. US actor Leonardo DiCaprio has issued an impassioned call for immediate action on climate change in "Before the Flood", a documentary film making its premiere in Paris on October 17. DiCaprio takes viewers around the world to meet experts and politicians in order to reveal the scale of the problem, its effects and the paths towards solutions. / AFP PHOTO / CHRISTOPHE ARCHAMBAULT