One of the world’s leading climatologists has warned that US presidential candidate Donald Trump is a “threat to the planet” because of his denial of global warming.

Professor Michael Mann, whose work showing how humans had caused the Earth’s temperature to rise at an unprecedented rate helped the International Panel on Climate Change win the Nobel Peace Prize, said he and other scientists had decided to speak out because of “the irreparable harm that would be done by a climate change-denying, anti-science-driven Trump presidency”.

Mr Trump has described climate change as “bullshit” and a hoax designed by China to undermine the US economy, although he later denied believing this and claimed such comments were meant to be jokes.

However, at the end of last month he gave a strong signal of his views when he appointed a prominent climate change sceptic, Myron Ebell, to run the US Environmental Protection Agency’s transition team if the Republican wins the election.

In an article on the EcoWatch website headlined, Yes, Donald Trump is a threat to the planet, Professor Mann, of Pennsylvania State University, wrote: “In just a matter of weeks, we will be confronted with a critical decision.

“It is not mere hyperbole to assert that we are facing a make-or-break election as far as climate change is concerned.

“In the current presidential contest, we could not have a more stark choice before us, between a candidate who rejects the overwhelming evidence that climate change is happening and a candidate who embraces the role of a price on carbon and incentives for renewable energy.

“If you care about the planet, the choice would seem clear. If the appropriate catch-phrase for the 1992 election was ‘It’s The Economy Stupid!’ then this time around it ought to be ‘It’s the planet stupid!’”

He said the US had to choose whether to continue Barack Obama’s “successes” on climate change or “retreat back into the energy-equivalent of the stone age, continuing to degrade our planet through the profligate burning of increasingly dangerous fossil carbon even as the rest of the world moves forward, embracing the renewable energy revolution destined to be the hallmark of the 21st century”.

Professor Mann, whose new book The Madhouse Effect: How Climate Change Denial Is Threatening Our Planet, Destroying Our Politics and Driving Us Crazy, was published last month, described Mr Trump’s attempts to deny he was a denier as a tactic used by those who sought to ignore global warming.

The Trump campaign, he said, was “attempting to pivot from one patently absurd climate change denial talking point – ‘it’s not happening!’ – to a seemingly more palatable, albeit equally indefensible one – ‘it’s natural, not human-caused!’

“To be clear, Donald Trump and his campaign still firmly rejects the scientific evidence that climate change is human-caused, opposing the only action (a reduction of fossil fuel burning) that can save us from ever-more dangerous climate change impacts," Professor Mann said.

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The academic and other scientists have set up a petition called “Scientists say: ‘Donald Trump is not who we are’” in an attempt to encourage other experts to make clear his “views on many pressing topics are at odds with scientific reality and represent a dangerous rejection of scientific thinking”.

Professor Mann said whether to accept climate science had become a “partisan political issue” in the US with Republicans who support action to address global warming subjected to “well-funded primary challenges”.

“History will judge us by what we chose to do at the crucial moment in time,” he said.

“The future of this planet could quite literally lie in the balance.”

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(Photo by Justin Sullivan/Getty Images) Getty Images Naked Donald Trump Statue Appears Across The States SAN FRANCISCO, CA - AUGUST 18: People gather around a statue depicting republican presidential nominee Donald Trump in the nude on August 18, 2016 in San Francisco, United States. Anarchist collective INDECLINE has created five statues depicting Donald Trump in the nude and placed them in five U.S. cities on Thursday morning. The statues are in San Francisco, New York, Los Angeles, Cleveland and Seattle. (Photo by Justin Sullivan/Getty Images) Getty Images Naked Donald Trump Statue Appears Across The States SAN FRANCISCO, CA - AUGUST 18: People gather around a statue depicting republican presidential nominee Donald Trump in the nude on August 18, 2016 in San Francisco, United States. Anarchist collective INDECLINE has created five statues depicting Donald Trump in the nude and placed them in five U.S. cities on Thursday morning. The statues are in San Francisco, New York, Los Angeles, Cleveland and Seattle. (Photo by Justin Sullivan/Getty Images) Getty Images Naked Donald Trump Statue Appears Across The States SAN FRANCISCO, CA - AUGUST 18: A passerby hugs a statue depicting republican presidential nominee Donald Trump in the nude on August 18, 2016 in San Francisco, United States. Anarchist collective INDECLINE has created five statues depicting Donald Trump in the nude and placed them in five U.S. cities on Thursday morning. The statues are in San Francisco, New York, Los Angeles, Cleveland and Seattle.(Photo by Justin Sullivan/Getty Images) Getty Images Naked Donald Trump Statue Appears Across The States SAN FRANCISCO, CA - AUGUST 18: A passerby has a picture taken with a statue depicting republican presidential nominee Donald Trump in the nude on August 18, 2016 in San Francisco, United States. Anarchist collective INDECLINE has created five statues depicting Donald Trump in the nude and placed them in five U.S. cities on Thursday morning. The statues are in San Francisco, New York, Los Angeles, Cleveland and Seattle. (Photo by Justin Sullivan/Getty Images) Getty Images Naked Donald Trump Statue Appears Across The States SAN FRANCISCO, CA - AUGUST 18: A passerby has a picture taken with a statue depicting republican presidential nominee Donald Trump in the nude on August 18, 2016 in San Francisco, United States. Anarchist collective INDECLINE has created five statues depicting Donald Trump in the nude and placed them in five U.S. cities on Thursday morning. The statues are in San Francisco, New York, Los Angeles, Cleveland and Seattle. 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The illegally placed statue drew hundreds of curious onlookers, who took selfie picture with the statue, which was signed "Ginger." A published report attributed the work to the anarchist collective INDECLINE, which titled the project "The Emperor Has No B--s." (Photo by Spencer Platt/Getty Images) Getty Images Naked Donald Trump Statue Appears Across The States NEW YORK, NY - AUGUST 18: Park authorities haul away a statue of a naked GOP presidential candidate Donald Trump that appeared in Union Square Park this morning on August 18, 2016 in New York City. The illegally placed statue drew hundreds of curious onlookers, who took selfie picture with the statue, which was signed "Ginger." A published report attributed the work to the anarchist collective INDECLINE, which titled the project "The Emperor Has No B--s." (Photo by Spencer Platt/Getty Images) Getty Images

While straightforward denial of climate science is still a factor in US politics, it has largely been accepted in the UK.

Even former Chancellor Nigel Lawson, head of the UK's leading sceptic think tank, the Global Warming Policy Foundation, admits greenhouse gases from fossil fuels cause global warming.