One of America’s most influential and popular scientists has issued a stark warning over what he termed the Trump administration’s rejection of science - saying it is a threat to the country’s “informed democracy”.

Neil deGrasse Tyson, host of the StarTalk podcast and TV show and director of the Hayden Planetarium at the American Museum of Natural History, said when he grew up, the US had relied on science to drive its innovation. But no longer.

“People have lost the ability to judge what is true and what is not, what is reliable, what is not reliable,” he says in a video posted on Facebook. “That’s not the country I remember growing up in. I don’t remember any other time where people were standing in denial of what science was.”

Mr Tyson’s comments came as many thousands of scientists and their supporters prepare to hold marches to highlight what they say is the Trump administration’s decision to reject science on issues ranging from climate change to public safety.

They say Donald Trump’s executive order to roll ball Barack Obama’s climate protections, its removal of funding for the Environmental Protection Agency and its unwillingness to say if the US will remain part of the Paris climate accord, are deeply dangerous.

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“When you have people who don’t know much about science and stand in denial of science and rise to power, that is a recipe for the dismantling of our informed democracy,” he said.

The Huffington Post said Mr Tyson has been campaigning to “Make America Smart Again” since Mr Trump won the election last year. Just last month, he said the US would need more than an intelligence boost if Mr Trump’s proposed budget cuts to key areas including science were passed.

His video includes various news clips and reports about the danger from climate sceptics and those who campaign against vaccinations.

One of the clips is of Vice President Mike Pence when he was a congressman rejecting the existence of evolution. “Let us demand that educators around America teach evolution not as fact, but as theory,” Mr Pence is seen to say in the clip.

Andrew Rosenberg, director of the Centre for Science and Democracy at the Union of Concerned Scientists, told The Independent that the Trump administration’s stance on science was even more extreme than that of George W Bush, one of whose first acts as president was to turn his back on the Kyoto Treaty.