While playing golf in Florida in temperatures of 72F (22C), Donald Trump conflated freezing temperatures for 17 million Americans with climate change. In a tweet – of course – the Denier-in-Chief wrote: “In the East, it could be the COLDEST New Year’s Eve on record. Perhaps we could use a little bit of that good old Global Warming that our Country, but not other countries, was going to pay TRILLIONS OF DOLLARS to protect against. Bundle up!”

The US President has form; this is only the latest Trump tweet to link the temperature in a single place at one time to the existence of global warming. “It’s freezing and snowing in New York – we need global warming,” he said in 2012. The following year, he declared: “Ice storm rolls from Texas to Tennessee – I’m in Los Angeles and it’s freezing. Global warming is a total, and very expensive, hoax!”

We shouldn’t be surprised, but we should be worried. Some of his followers, and not just on Twitter, will believe his ludicrous remarks, and they could plant a seed of doubt among others.

Of course, short-term weather conditions are very different to long-term climate trends. Scientists point out that cold snaps will be balanced out by hot spells elsewhere. Although not yet proven, there is even some evidence that the very opposite of what President Trump claims is true: that climate change is associated with more extreme cold events as well as heat and drought.

Away from Planet Trump in the real world, 2017 is on course to be one of the three hottest on record, and possibly the hottest. The evidence of our own eyes is powerful: the spate of hurricanes that engulfed the Caribbean and the south of America; unprecedented wildfires in California; and flooding in India and Bangladesh. The victims were often among the world’s poorest people. As Theresa May, not noted for her personal commitment to the environment, argued this month: “There is a clear moral imperative for developed economies like the UK to help those around the world who stand to lose most from the consequences of manmade climate change.”

Ten great things Donald Trump will give the world in 2018

Mr Trump, unfortunately, is heading in the opposite direction. He has pulled the US out of the Paris accord on climate change, signed by Barack Obama. The Trump administration, which includes several deniers and fossil-fuel champions, removed climate change from the list of threats in its national security strategy. The Environmental Protection Agency curbed its own focus on climate science.

The administration is in denial of its own evidence. Its Accountability Office reported in October that the government has spent more than $350bn (£259bn) in the past decade responding to extreme weather and fire events, warning of much bigger bills in future unless global emission rates fall. The government’s Climate Science Special Report in November found “no convincing alternative explanation” for the changing climate other than “human activities, especially emissions of greenhouse gases”. Almost 140 years of weather records speak volumes: 97 per cent of climate scientists who have published papers believe not only that the planet is warming, but that this is probably due to human activity.