Humanity is facing its greatest threat in a thousand years, Sir David Attenborough has warned the United Nations climate conference in Poland.

The naturalist and climate campaigner has taken the 'People's Seat' at the COP24 meeting, giving a voice to the millions around the world who are already affected by global warming.

He told delegates that they must act.

"The continuation of our civilisations and the natural world upon which we depend, is in your hands," he said.

Later, in an interview with Sky News, he said: "We have so much knowledge, skill and ingenuity.


"Of course we can do something about it. The question is how much.

Attenborough urges global community to aim 'high' at climate conference

"Homosapiens is a very ingenious species. It got us into this mess, true, but it knew not what it did. I believe now is the moment to use that ingenuity and that passion to get us out of it."

Three years ago, world leaders gathered in Paris to sign a ground-breaking deal to cut carbon emissions and hold back the rise in global temperatures to two degrees.

But not all countries have honoured their commitments and in a keynote address to delegates at the conference in Poland, UN Secretary General Antonio Guterres chided politicians for being so slow to act.

"Climate change is the single most important issue we face," he said.

"It affects all our plans for sustainable development and a safe, secure and prosperous world.

"So, it is hard to comprehend why we are collectively still moving too slowly - and even in the wrong direction."

Donald Trump is intent on withdrawing the United States from the Paris deal, saying that it damaged the American economy.

But the US is responsible for 13% of greenhouse gas emissions, the second largest polluter after China.

If it does ditch the deal it would mean the rest of the world would have to make even greater cuts.

Climate change: 'Poor will suffer first'

Based on current, rising, greenhouse gas emissions the world is expected to be more than three degrees warmer at the end of the century than it was before the industrial revolution.

Under the pledges made in Paris emissions would simply level off.

But they need to be cut by 25% by 2030 to limit the temperature rise to 2C

And even steeper cuts of 55% are needed to keep the rise to 1.5C, now seen as the safe limit to avoid the worst effects of climate change.

Earlier this year, scientists on the Intergovernmental Panel on Climate Change said the lower limit would mean 420 million fewer people would be affected by rising sea level, famine and water shortage.