SO WHO you gonna believe? The scientist with a long list of sombre facts at his fingertips or the guy in the ten-gallon hat with his jaw clamped round a cigar and oil stains on his nice white suit?

That isn’t exactly what President Barack Obama said yesterday when he announced sweeping new plans to reduce greenhouse gasses from US power plants. But the implication was surely there in a country more sharply divided than most on the extent and causes of climate change – and traditionally more wedded than most to oil and coal.

Obama’s plan aims to cut greenhouse gas emissions by 32 per cent by 2030. This will strike many people as a good and sensible initiative. It will also strike some Republicans and backwoods deniers of almost anything and everything as apostasy: the abandonment of a long-held loyalty to oil and coal.

Too many Americans, especially those on the stars-and-stripes right, more or less refuse to believe that climate change exists. Such deniers insist that any suggested curtailment of their right to burn coal and oil however they want, and in whatever quantities they choose, and with however much smoke it makes, is more or less a sin against God and America, etc.

It is thought that there will be legal and administrative challenges from many states, especially those heavily reliant on coal-fired power stations.  So none of this will be easy. And Obama will be long gone before the date he has set for his big environmental clean-up. But good on him for making a stand at last.

Oil, coal and gas from fracking represent the brutal buck, the shortest line to a profit. The free market likes such solutions. That is why Republicans in the US and, increasingly, our own Conservatives so often stand against green-minded alternatives.

The US and China are the world’s biggest polluters and users of fossil fuels. If those two mighty countries show they are prepared to do something about climate change, then others are more likely to follow suit. Also, both are massive countries with the space and potential to push ahead with green energy.

Obama is right to say: “We are the first generation to feel the impact of climate change and the last generation that can do something” about climate change; right to intone: “We have to get going.”

And good on him too to add a personal note in saying: “I don’t want my grandkids not to be able to swim in Hawaii or climb a mountain and see a glacier because we didn’t do something about it.”

I feel the same about my grandchildren when or if they arrive. Hell, I wouldn’t mind a swim in Hawaii or a sight of a glacier myself right now.