Conspiracy theorists can easily be dismissed or even laughed off as unthinking, sometimes paranoid ideologues with a tainted view on society.

Their language is often wrapped around power and freedom and speaks of global threats to undermine “our” way of life.

Some outspoken deniers of the risk the world faces from human-caused climate change will often evoke such rhetoric, claiming efforts to legislate to cut emissions of greenhouse gases are socialist or communist plots to redistribute wealth.

But most who believe this rhetoric would never think of turning to force. Anders Behring Breivik did.

The 32-year-old Norwegian Christian fundamentalist is facing trial for the massacre of 76 people in a shooting and bombing attack in Oslo.

Revealed in his online manifesto is a deep paranoia of “Marxists” and of Islam. But Breivik also accepted the conspiratorial thinking of some climate sceptics.

In the manifesto, Breivik cites “environmentalist organisations” as being “smoke screens” for “cultural Marxists”. He also includes in this bracket, groups that advocate for animal rights, human rights, feminism and anti-racism

In a section of his manifesto entitled “Green is the new Red — Stop Enviro-Communism!”, Breivik writes:

“The neo-communist agenda uses politicised science to propagate the global warming scam in order to implement their true agenda; global Marxism.

“You might know them as environmentalists, enviro-communists, eco-Marxists, neo-Communists or eco-fanatics. They all claim they want to save the world from global warming but their true agenda is to contribute to create a world government lead by the UN or in other ways increase the transfer of resources (redistribute resources) from the developed Western world to the third world.

“They are using our trust and faith in science to spread lies and hysteria that will allow Marxists to implement socialist — solutions to a problem that never actually existed.”

One section of Breivik’s manifesto points readers to a video clip of Lord Christopher Monckton, the climate change sceptic who is nearing the end of an Australian tour supported by mining magnate Gina Rinehart, The Climate Sceptics political party and part-funded by the Association for Mining and Exploration Companies.

The video is an excerpt of Lord Monckton’s October 2009 speech to Bethel University in St Thomas, Minnesota. The comparison to Breivik’s manifesto is chilling.

In the video, Lord Monckton evokes former British Prime Minister Winston Churchill and the fall of the Berlin Wall and suggests moves to kerb greenhouse gas emissions is cover for the creation of a global government.

Referring to the 2009 UN climate change conference in Copenhagen, which was just weeks away at the time of his speech, Lord Monckton said: “A world government is going to be created. The transfer of wealth from the countries of the West to Third World countries in satisfaction of what’s called coyly a climate debt because we have been burning CO2 and they haven’t and we have been screwing up the climate — we haven’t been screwing up the climate, but that’s the line.

“Now the apotheosis is at hand. They are about to impose a communist world government on the world.”

Lord Monckton told the audience: “In the next few weeks, unless you stop it (the signing of the Copenhagen accord), your president will sign your freedom, democracy and prosperity away forever. It’s here in your great nation,” he said.

“It is here that perhaps at this 11th hour at the 59th minute at the 59th second you will rise up and you will stop your president from signing that dreadful treaty.”

“In the weeks before his Australian tour at a conference in Los Angeles, Lord Monckton displayed a swastika on a large screen next to a quote from former Australian government climate change adviser Professor Ross Garnaut, accusing him of holding a “fascist” point of view.

Crikey called Lord Monckton this morning, but before we had time to ask a question, he said: “Having seen what that website (Crikey) is about I am disinclined to speak to you,” and then immediately hung-up.

But Lord Monckton’s rhetoric — as stirring and inspiring to some as it so obviously is — does not stand alone.

In November, UK Daily Telegraph columnist James Delingpole will tour Australia touting his book  Watermelons — The Environment Movements True Colours. Delingpole, an ardent climate sceptic, says his book shows how environmentalists are “green on the outside, red on the inside”.

Other high-profile Australian commentators have echoed such sentiments while promoting Lord Monckton.

Recently retired Liberal senator Nick Minchin revealed that he too believes environmentalism is a cover-story for communism. In 2009, speaking about global warming he told the ABC’s 4Corners.

“For 10 years the left internationally have been very successful in exploiting peoples’ innate fears about global warming and climate change to achieve their political ends.

“For the extreme left it provides the opportunity to do what they’ve always wanted to do, to sort of de-industrialise the Western world. You know the collapse of communism was a disaster for the left, and the, and really they embraced environmentalism as their new religion.”

On Thursday at an event in Melbourne, the Institute for Public Affairs continues its promotion of a series of speaking engagements by Czech Republic President Vaclav Klaus.

Among the titles of his talks at cities across Australia, there has been “Climate change the dangerous faith”, “Climate change a new ideology” and “The mass delusion of climate change”.

If the horrific events in Norway have told us anything, it is that such conspiratorial rhetoric can shape some minds in the most dangerous and chilling of ways.