Last week, the Global Warming Policy Foundation published a blog with a provocative headline: "Greta Thunberg: climate figurehead or PR puppet?"

GWPF is a "think-tank" that spends its time pouring scorn on what it calls "the contested science of global warming". They're just asking questions here. Bravely trying to get to the bottom of an issue.

Greta Thunberg is the 16-year-old Swedish activist who has shot to global fame after becoming the de-facto leader of the increasingly global School Strike 4 Climate Action. But is she a puppet? Or are her detractors full of shit? I'm just asking questions here.

"There are more and more doubts about the 'story' of the climate girl from Sweden," writes Stefan Winterbauer in an article cited by the GWPF, after first appearing on the German site meedia.de.

This piece was the latest in a flurry of blogs and magazine articles innocently asking questions about Thunberg. Most notably, a piece in the right-wing Swiss magazine Die Weltwoche, which investigated why Thunberg was getting so much support, when another teen activist, Izabella Nilsson Jarvandi – who campaigns against migration and "globalism" – barely gets noticed.‏

So what's the evidence against Greta Thunberg?

According to meedia.de, "Weltwoche reveals that shortly after Greta began her school strikes, her mother, a well-known opera singer, published a book. On the day of the book's release, PR man Rentzhog published a picture of Greta on [school] strike on Instagram and published an article about her on Facebook."

Here I was getting inspired by one teenager's quest to get the world to take action on climate change – but it turns out her activism is just part of a well worked PR campaign for an opera-singer’s book on raising children with autism (both Greta and her younger sister have autism).

Not only that, but when she made a speech at the UN climate conference in Katowice late last year, Swedish public television filmed her. There wasn't much of a crowd in the room where Thunberg delivered her address, but Swedish TV gave "the false impression that she had spoken to a large audience". Imagine pointing your camera at a person giving a speech, rather than the room in front of them. Truly, a cunning deception.

Winterbauer also notes that "articles dealing with the role of PR consultant Ingmar Rentzhog have been few and mostly in the right-wing media or from Sweden". So who is this Ingmar guy?

I called him up to ask.

"They think that I am the PR genius behind Greta," he told me. "That I write her speeches and arrange meetings for her with journalists. That's simply not true."

Rentzhog says that, after Thunberg began her campaign, he gave her advice through We Don't Have Time, a tech start-up that aims to amplify local climate initiatives and bring them to global audiences through social media. He says he’s got nothing to do with Ernman's book, the profits from which, Thunberg has said, will go to a range of environmental, animal rights and other charities.

Rentzhog first became aware of Thunberg after seeing her solo protest outside the Swedish parliament on his way to work and posting a short essay and a picture of her on social media that soon went viral. Thunberg herself has said she talked to a range of activists before coming to her school strike idea.

Since right-wing blogs started attacking Thunberg in December, Rentzhog says he and staff at the organisation he founded, We Don't Have Time, have received hate email.

"Many people love to spread rumours saying that I have people 'behind me' or that I'm being 'paid' or 'used' to do what I’m doing. But there is no one 'behind' me except for myself," Thunberg wrote on Facebook on Saturday. "My parents were as far from climate activists as possible before I made them aware of the situation.... When I told my parents about my plans they weren’t very fond of it."

While the GWPF are keen to debunk the conspiracy of "the teenager who cares about climate change", they're less sceptical when it comes to some other pretty out there ideas.

Take the group's annual State of the Polar Bear report, by Susan Crockford, a woman who has made a name for herself in recent years by boldly stating that polar bears are doing just fine, no matter what the scientists tell you. Or their promotion of the theory that cosmic rays, not greenhouse gases, are causing global temperature increases.

Thousands of students all over the world have joined the School Strike 4 Climate Action campaign, inspired by Thunberg. Walk-outs took place in Belgium, Germany, Switzerland and Australia at the back end of 2018. This is a group of teenagers who have been inspired to make the world a better place. For a group who spend their days trolling environmentalists on the worst parts of the internet, and staggering into the the House of Lords to bemoan BBC bias, they must seem very threatening.