An influential thinktank that has led the backlash against the government’s net zero policy has received funding from groups with oil and gas interests, according to tax documents seen by the Guardian and OpenDemocracy. Though the Global Warming Policy Foundation (GWPF) has always said it is independent of the fossil fuel industry, the revelations about its funding will raise questions over its campaigning. The thinktank has always refused to disclose its donors, but tax documents filed with US authorities reveal that one of its donors has $30m (£24m) of shares in 22 companies working in coal, oil and gas. Over four years the GWPF’s US arm, the American Friends of the GWPF, received more than $1m from US donors. The vast majority of this, $864,884, was channelled to the UK group, with some being held back for expenses. Of the £1.45m the GWPF has received in charitable donations since 2017, about 45% has come from the US. It received $210,525 in 2018 and 2020 from the Sarah Scaife Foundation – set up by the billionaire libertarian heir to an oil and banking dynasty. The US-based foundation has $30m-worth of shares in 22 energy companies including $9m in Exxon and $5.7m in Chevron, according to its financial filings. Between 2016 and 2020, the American Friends of the GWPF received $620,259 from the Donors Trust, which is funded by the Koch brothers, who inherited their father’s oil empire and have spent hundreds of millions of dollars funding the climate denial movement. “It is disturbing that the Global Warming Policy Foundation is acting as a channel through which American ideological groups are trying to interfere in British democracy,” said Bob Ward, policy and communications director at the LSE Grantham Research Institute on Climate Change and the Environment. The GWPF was set up by Lord Lawson, a former Conservative chancellor, in 2009, to challenge the “costs and implications” of measures to tackle climate change. Since then, it has gained prominence in UK politics, counting Conservative MPs and peers as supporters and trustees. Craig Mackinlay, who runs the Net Zero Scrutiny Group (NZSG), a committee of about 20 parliamentarians, has supported the GWPF in its campaigning and two advisers to the GWPF were recently hired by Mackinlay’s parliamentary office as researchers. The NZSG says it does not question climate science, but exists to question the costs of reaching net zero. Steve Baker, the Wycombe MP who has led much of the criticism towards the government’s net zero policies, is a trustee of the GWPF and vocally supports the group, recently sharing a report by the thinktank that denied the climate emergency exists. He is a prominent member of the NZSG, and has recently campaigned for fracking, inviting the shale gas industry to speak to MPs and members of the rightwing press in parliament. After campaigning from the NZSG, the government recently declared that fracking companies would be allowed to continue their research in the UK. Shale gas wells that were supposed to be filled in with concrete this summer have been given a new lease of life, after campaigning from Baker, Mackinlay and others associated with the NZSG. There are fears that the UK’s net zero ambitions could be watered down with further campaigning from MPs on the right of the party. The Guardian has asked Baker and Mackinlay whether they would reconsider their connections to the GWPF in light of the news about the thinktank’s funding. Mackinlay said: “Do look at my staff declarations of interests as properly recorded in the parliamentary register; all totally transparent and for the world to see. Make of it whatever you wish.” Baker said the allegations “appear to be ridiculous”, adding: “It is an extraordinary fact that the same newspapers and commentators who would usually be the first to protest any kind of poverty are wasting the public’s time with these attempts to distract from the real issues at hand. It would be better if the political world focused their attention on how our current energy strategy has driven up energy prices and contributed to the terrible cost-of-living crisis that so many are experiencing.” The funding has caused fears that the culture wars over climate denial in the US could be being imported to UK politics, and funded by billionaires with links to “big oil”. Ed Miliband, the shadow climate secretary, said: “US rightwing groups with links to big oil are desperate to stop action against the climate crisis. Now they are trying to extend their reach into UK political debate. “Opposing action on the climate emergency will drive up bills for consumers because green power is now cheaper, cleaner, and quicker than fossil fuels.” Already the rumblings of a culture war have begun, with the former Ukip leader Nigel Farage calling for a referendum on net zero, and Baker, a vital figure in the Brexit campaign, declaring he wanted to “do for net zero what [he] did for Brexit”. A spokesperson for the GWPF said: “We do not accept donations from anyone with an interest in an energy company. We turn down many offers of funding from people with vested interests. I am not sure this is true of any group on the other side of the debate. “Donor’s Trust is a middleman, matching donors to those seeking funding. Disbursements are not made from a homogenous pool of money – recipients of funds know the identity of the original donors. We are therefore able to vet them in line with our funding policy. “I suggest you also consider what constitutes an ‘interest’. Money that is inherited does not create an ‘interest’, let alone a vested one. The wealth that ultimately created the Scaife Foundation was created at the end of the 19th century and the start of the 20th. It would be ludicrous to suggest that three generations on, it represents an oil company interest.” Adam Bychawski is a reporter for OpenDemocracy