Image copyright PA Media Image caption Rowan Williams said some people have 'sinister' reasons for denying climate change

The environmental crisis is the "largest challenge ever" to the human race, the former Archbishop of Canterbury has said.

Interviewed by artist Grayson Perry for BBC Radio 4's Today programme, Rowan Williams said climate change is "everybody's problem".

Dr Williams said some people do not believe in the crisis because it is "just too uncomfortable to face".

But he warned that for others there is a more "sinister" reason for denial.

Perry, who was the day's guest editor on the Today programme, asked Dr Williams what the driving force was behind people disbelieving climate change.

Dr Williams, who held the senior Church of England post between 2002 and 2012, said some people were reluctant to acknowledge the climate crisis because it would require them to change their behaviour.

"For others I think there's a rather a more sinister feeling that this must be some kind of conspiracy," Dr Williams said, citing those who might think climate change has been "invented by communists, illuminati or some mysterious group".

Dr Williams added: "So that's something I worry about a bit more, the idea that there are people who genuinely believe climate change is a huge confidence trick."

Perry, a Turner Award prize winning artist, said he wanted to speak to Dr Williams as he was an "expert on the nature of belief", which is not "necessarily about facts".

Image copyright Graham Eva Image caption Grayson Perry is the first of this year's four guest editors on Today over Christmas week

Discussing this month's general election, Dr Williams said there were "myths" on both sides of the political spectrum.

"Broadly on the Conservative side, there's an assumption still that most of our ills are caused by something coming in from outside," Dr Williams said, adding it was a "compelling" and "comforting" myth.

Whereas a "left wing myth" would be the idea that it is possible to "legislate justice into being" and make tragedy and misunderstanding impossible, Dr Williams said.

Dr Williams spoke to Perry as part of the latter's guest editorship of the Today programme, the reins of which are handed to high-profile public figures during the week between Christmas Day and New Year.

This year's line-up includes environmental activist Greta Thunberg, Supreme Court President, Baroness Hale, spoken word artist George the Poet and journalist Charles Moore.