Sir David Attenborough is calling on global leaders to step up their actions to curb climate change, saying that they are in denial about the dangers it poses despite the overwhelming evidence about its risks.
The TV naturalist said those who wield power need to use it: "Wherever you look there are huge risks.
"The awful thing is that people in authority and power deny that, when the evidence is overwhelming and they deny it because it's easier to deny it - much easier to deny it's a problem and say 'we don't care'," Sir David said.
In terms of climate change, "we won't do enough and no one can do enough, because it's a very major, serious problem facing humanity; but at the same time it would be silly to minimise the size of the problem", he told Sky News.
Later this year, a crucial UN climate summit will be held, at which world leaders have pledged to agree to tough cuts in their carbon emissions, to ensure the increase in global warming does not exceed 2°C - beyond which its consequences become increasingly devastating.