'The biggest scam since the devil': The challenge to convince America's climate change sceptics there is a problem
The world's attention is focused on the climate change talks in Paris. The outcome there is rightly seen as crucial to the survival of the world as we know it.
But in parts of America there are many people who see the negotiations as a hoax. A fraud. An attempt by the scientific community to pursue its own financial agenda.
Yes, this is a nation filled with conspiracy theorists.
We visited Oklahoma, a state in the American heartland where climate change denial is encouraged by local politicians.
Earlier this year, the state's senior politician, James Inhofe, infamously - and preposterously - held up a snowball on the floor of the US Senate as proof that global warming is not happening.
In fairness, Oklahoma is divided. There are sceptics who say that global warming is not occurring.
As one cotton farmer, Danny Davies, told me bluntly, "It's the biggest scam and phobia that's been perpetrated on the world since the Devil."
But we also met ranchers who are acting already to try and prevent the extreme weather from devastating their land.
Farmer Jimmy Emmonds is planting rugged native grasses and seeds in his fields to lessen erosion.
His grandfather survived the Dust Bowl years, so Jimmy is a man who knows about survival and resilience, and the need for preparation.
President Obama has become a leader in the climate change talks, helped by falling emissions in America.
That is partly because of investments in solar and wind power. It is also due to the explosive growth in fracking, which is - in relative terms - a lower-carbon source of fuel.
But back home, Republicans are seeking to derail any progress in Paris.
The campaign trail is being criss-crossed by candidates who see the President's engagement in the negotiations as a betrayal.
To most of the world, global warming is a harsh reality that must be addressed with urgency.
But in America, before there can be a consensus on the solution, there are millions who must first be convinced there is a problem.