naturalist Sir David Attenborough

Sir David Attenborough: Climate change 'our greatest threat'

The broadcaster said it could lead to the collapse of civilisations and the extinction of "much of the natural world".

He was speaking at the opening ceremony of United Nations-sponsored climate talks in Katowice, Poland.

The meeting is the most critical on climate change since the 2015 Paris agreement.

Sir David said: "Right now, we are facing a man-made disaster of global scale. Our greatest threat in thousands of years. Climate change.