EVEN before Donald Trump hijacked the Republican Party, he was loudly declaring that the science of climate change, like Barack Obama, had not been born in the United States. It was, he insisted in 2012, a Chinese hoax "created by and for the Chinese in order to make US manufacturing non-competitive."
Trump has promised that within 100 days of taking office he will "cancel" the Paris Climate agreement of last December and "stop all payments of US tax dollars to UN global warming programmes". He will also rescind the executive actions that President Obama has taken to limit US emissions of carbon dioxide, especially in the field of electricity. (In effect, this would have closed almost all coal-fired power stations in the US.)
Now, in practice, Trump can't cancel the Paris Agreement, which has been signed by 195 countries. He can pull the US out of the treaty (as George W Bush, another climate change denier, pulled the US out of the Kyoto Protocol on Climate Change in 2001), but he can't stop other countries from carrying on with the agreed cuts in emissions -- which they may well do, because they understand how dangerous the situation is.
He can cancel all President Obama's executive orders and encourage Americans to burn all the fossil fuels they want. Indeed, he has appointed Myron Ebell, a professional climate change denier, to be the new head of the Environmental Protection Agency. Ebell's mission is to gut it, and he will. But even Trump cannot save the American coal industry, because it has simply become cheaper to burn natural gas.
The net effect of a Trump presidency will certainly be to slow the rate at which American greenhouse gas emissions decline, but simple economics dictates that they will not actually rise, and might even fall a bit. Renewable energy is getting cheaper than fossil fuels in many areas, and even Trump would find it hard to increase the large hidden subsidies to oil and coal any further.