PRINCE Charles has urged world leaders to act quickly to combat climate change.

He called it the “wolf at the door” in a foreword to a new Ladybird book he has co-written called Climate Change.

5 Prince Charles has co-written a new Ladybird book called Climate Change in a bid to raise awareness of the 'wolf at the door' Credit: Getty Images

He wrote: “I hope this modest attempt to alert a global public to the ‘wolf at the door’ will make some small contribution towards encouraging requisite action, action that must be urgently scaled up and scaled up now.”

His warning will be seen as a message to Theresa May and Donald Trump, who will become US President today.

5 Prince Charles made a plea to Tony Blair in 2005 and to world leaders in Paris two years ago Credit: Getty Images - WireImage

Mr Trump has said he plans to meet the Prince “in the coming weeks”, which would give the royal the chance to press home his point.

The sceptic President has previously said: “The concept of global warming was created by and for the Chinese to make US manufacturing non-competitive.”

Clarence House said a meeting had not been planned but they were likely to meet at a State visit for Mr Trump.

5 Donald Trump plans to meet Prince Charles 'in the coming weeks' after becoming US President today Credit: AP:Associated Press

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5 Prince Charles cares passionately about raising global awareness about climate change Credit: News Group Newspapers Ltd

A spokesman for the Prince said: “He regards climate change as the No1 threat to the planet and it is what he cares most passionately about.”

Mr Trump discussed his plans for the meeting when he was having his photo taken for the cover of Time magazine at the end of last year.

5 The Prince believes climate change is the number 1 threat to the planet Credit: AP:Associated Press

He noticed the photographer, Nadav Kander, had done a portrait of Prince Charles in 2013.

Michael Scherer, who wrote a profile of Mr Trump, said: “Trump was excited because he plans to meet Prince Charles in the coming weeks.”

The Prince spoke to world leaders about the dangers of climate change in Paris two years ago and wrote to then PM Tony Blair in 2005.