Leonardo DiCaprio tells summit climate change 'is fact'

Leonardo DiCaprio has said climate change "is fact" as he addressed the UN Climate Summit in New York.

The newly-appointed UN Messenger of Peace said he was a "concerned citizen" and "one of the 400,000 people who marched in the streets of New York on Sunday."

"As an actor I pretend for a living - I play fictitious characters with fictitious problems. I believe that mankind has looked at climate change in that same way, as if it were a fiction," DiCaprio told the audience.

"But I think we all know better than that now ... none of this is rhetoric and none of this is hysteria, it is fact".

The Prime Minister is joining more than 120 world leaders, including US president Barack Obama, today at a summit convened by United Nations secretary general Ban Ki-Moon with the intention of restoring momentum to the international battle against climate change.

Downing Street said Mr Cameron will press for strong and early commitments from the international community ahead of next year's Paris conference, when a new global deal on action to limit climate change is planned.

More: World leaders under pressure over climate change promises

Protesters took to the streets of New York again this evening, as world leaders prepare to fly in for a summit on climate change.

Organisers say this meeting - and next year's in Paris - will be different and insist promises made will be kept. ITV News' Science Correspondent Alok Jha reports:

Global emissions of carbon dioxide are set to rise again this year to reach a new record high, scientists have warned.

Despite increasingly urgent warnings over the need to curb greenhouse gases to avoid "dangerous" climate change, emissions are estimated to be rising by 2.5% this year, to a record 40 billion tonnes.

The stark warning that time is running out to tackle greenhouse gas emissions comes ahead of a major UN conference on climate change on Tuesday.

Thousands of people marched through Central London earlier to highlight the climate change crisis to the UK government. Similar rallies also took place simultaneously across the globe.

Actress Emma Thompson says people who deny that man-made climate change is taking place are "a little bit bonkers".

Speaking to ITV News, the Harry Potter and Love Actually star also described the reliance on polluting fossil fuels as "a form of collective suicide".

Demonstrations are taking place around the world ahead of a major UN conference on climate change on Tuesday.

Over 2,000 protests have taken place around the world, including in London.

Among the speakers at the New York summit will be Hollywood star Leonardo DiCaprio, who was recently made a UN 'Messenger of Peace' to help promote international action on climate change.