The legendary filmmaker Sir David Attenborough has spoken out about climate change.
The Frozen Planet star believes that if the world's temperature continues to rise, there could be dangerous consequences for the human race.
His comments come as world leaders meet in South Africa to try to hammer out a plan to cut greenhouse gas emissions.
But getting all the countries to agree is proving difficult.
The three most common greenhouse gases are carbon dioxide, methane and nitrous oxide.
Scientists think these gases trap heat in the atmosphere, acting like a blanket and causing the planet to become warmer: the 'greenhouse effect'.
As his latest documentary, Frozen Planet, comes to an end, Sir David's seen for himself the effects of climate change in the North and South poles.
He's spent much of his career travelling the world and feels it's extremely important that something's done to protect the planet before it's too late.