If he were not doing such enormous harm to the world, he would be a total joke.

November 2012 (in a tweet): “The concept of global warming was created by and for the Chinese in order to make US manufacturing non-competitive.” Separately he said that climate change is a “hoax”.

October 2018, in an interview about climate change on CBS: “I don’t think it’s a hoax. I think there’s probably a difference. But I don’t know that it’s man-made. He said, “I think something’s changing. I’m not denying climate change, but it could very well go back.  it’ll change back again. You know, we’re talking about over millions of years.”  Does he not understand that we do not have millions of years?  If by the middle of this century we have not reduced carbon emissions to zero, we will have passed the Rubicon into irreversible climate change and its catastrophic consequences for the entire globe.

Over a period of millions of years, we may have another Ice Age, with much of the Earth again covered by gigantic glaciers, obliterating human civilisation.

Scientists and thinking people are much less concerned with millions of years, about which we can do nothing, than with the next few decades, during which the fate of the human race and all life on the planet is in our hands.

During this month, January 2019, following a long spell of unusually mild weather, the eastern parts of the USA were hit by bitter winds and driving snow.

Predictably, the child-like Trump asked on Twitter how climate change could be real if it was so cold outside. “Wouldn’t be bad to have a little of that good old fashioned global warming right now!”

Such infantile, simplistic, irresponsible outbursts, like those concerning US trade agreements and international treaties please his excitable, ill-informed supporters, which is precisely what they are intended to do.

Whenever it snows in Manhattan, he questions climate change, deliberately confusing climate and weather.

Any Dumbo must be able to comprehend that, although New York may suffer an ice-storm  –  that is an unpleasant  short-term weather phenomenon  –  average temperatures  – That is an aspect of long-term climate  –  are rising.

Like Great Britain, the north-eastern USA  enjoyed a relatively balmy autumn and early 1918-19 winter. It is not surprising that Trump did not resort to Twitter to claim this unusual weather proves global warming, which in itself it does not, of course.

Trump’s own government agencies, NASA and the Oceanic and Atmospheric Administration (OAA), have confirmed that the past 4 years have been the warmest on record across the USA and the rest of the world and the world has not had a cooler-than-average year since 1976, or a cooler-than-normal month since the end of 1985.

Whether he accepts these scientific findings will depend on his audience, on whether he wishes to change the subject of media interest on the day and  – for all we know  – it may depend on the state of his digestion.

Trump vacillates because his overwhelming concern is to please “the folks” who voted for him: the Appalachian miners, who want to continue digging up the dirtiest fossil fuel, the petrol-heads who want to continue driving their SUVs on dirt-cheap gasoline and the billionaire moguls of the energy industry, who will back and fund his election campaign for a second term.