Sir David Attenborough has issued his strongest statement yet on the threat posed to the world by climate change.
In the BBC programme Climate Change - The Facts, the veteran broadcaster outlines the scale of the crisis facing the planet.
Sir David says we face "irreversible damage to the natural world and the collapse of our societies".
But there is still hope, he says, if dramatic action to limit the effects is taken over the next decade.
Sir David's new programme lays out the science behind climate change, the impact it is having right now and the steps that can be taken to fight it.
"In the 20 years since I first started talking about the impact of climate change on our world, conditions have changed far faster than I ever imagined," Sir David states in the film.
"It may sound frightening, but the scientific evidence is that if we have not taken dramatic action within the next decade, we could face irreversible damage to the natural world and the collapse of our societies."
Speaking to a range of scientists, the programme highlights that temperatures are rising quickly, with the world now around 1C warmer than before the industrial revolution.