How Leonardo DiCaprio became one of the world's top climate change champions

The Oscar-winning actor's environmental activism may not quite stretch back to What's Eating Gilbert Grape but he has steadily schooled himself on the oceans and climate change since the 1990s

Leonardo DiCaprio was a climate champion long before the actor wrapped himself in an animal carcass, vomited up raw bison liver, and risked hypothermia for his Oscar-winning role in Revenant.

DiCaprio used his acceptance speech for best actor to urge a global audience to reject the "politics of greed", and support leaders willing to take action against climate change.