When Eric Schmidt was asked on a radio show in 2014 why Google was supporting an ultra-conservative climate-denying pressure group in Washington, the then chairman of the internet giant offered an unequivocal response: it was wrong and Google was not going to do it again.

“The consensus within the company was that that was some sort of mistake and so we’re trying to not do that in the future,” Schmidt told NPR. People who opposed or questioned climate science were making the world “a much worse place”, he added, and Google “should not be aligned with such people”.

But five years later, Google still funds more than a dozen organisations that deny the climate crisis and oppose political action to try to solve it. Among them is the Competitive Enterprise Institute (CEI), the group that launched the notorious Cooler Heads Coalition two decades ago, a group of conservative and libertarian pressure groups dedicated to dispelling the “myths” of global heating.

Q&A What is the polluters project? Show Hide The Guardian has collaborated with leading scientists and NGOs to expose, with exclusive data, investigations and analysis, the fossil fuel companies that are perpetuating the climate crisis – some of which have accelerated their extraction of coal, oil and gas even as the devastating impact on the planet and humanity was becoming clear.

The investigation has involved more than 20 Guardian journalists working across the world for the past six months. The project focuses on what the companies have extracted from the ground, and the subsequent emissions they are responsible for, since 1965. The analysis, undertaken by Richard Heede at the Climate Accountability Institute, calculates how much carbon is emitted throughout the supply chain, from extraction to use by consumers. Heede said: "The fact that consumers combust the fuels to carbon dioxide, water, heat and pollutants does not absolve the fossil fuel companies from responsibility for knowingly perpetuating the carbon era and accelerating the climate crisis toward the existential threat it has now become." One aim of the project is to move the focus of debate from individual responsibilities to power structures – so our reporters also examined the financial and lobbying structures that let fossil fuel firms keep growing, and discovered which elected politicians were voting for change. Another aim of the project is to press governments and corporations to close the gap between ambitious long-term promises and lacklustre short-term action. The UN says the coming decade is crucial if the world is to avoid the most catastrophic consequences of global heating. Reining in our dependence on fossil fuels and dramatically accelerating the transition to renewable energy has never been more urgent.

For Google, providing financial backing to groups such as CEI and the Cato Institute – staunch free marketeers – has nothing to do with climate science, and everything to do with its effort to curry favour with conservatives on its most pressing issue in Washington: protecting an obscure section of the US law that is worth billions of dollars to the company.

The law – known as section 230 of the Communications Decency Act – was established in the 1990s, at a time when the internet was in its infancy, and helped to give rise to internet giants, from Google to Facebook, by offering legal immunity to the companies for third party comments, in effect treating them as distributors of content and not publishers.

Section 230, in effect, allowed Google and Facebook to be shielded from the kinds of libel laws that can ensnare other companies, such as newspapers.

The law has important advocates across the political spectrum, from Democrats who hail it as a triumph of free speech, to Republicans who say it has promoted free enterprise and innovation.

But now some lawmakers, including Republicans, think it might be time to revise section 230. The senator Ted Cruz, a Texas Republican, has said Google’s alleged bias in favour of Democrats means it is not a neutral platform and should not be protected from liability.

Google’s decision to give to groups such as CEI reflects an attempt to win friends in Republican and conservative circles, and support those lawmakers on the right who are champions of section 230.

“I think the future of conservatism is up for grabs in the Trump era,” said one person who is familiar with the company’s thinking on political giving. “We are in a moment where Google has been injected in a lot of culture wars … and there is a lot of hostility in conservative circles.”

There is little doubt that Google has a loyal friend in CEI. In a recent letter to members of Congress, CEI and other conservative groups called for the protection of section 230, saying it had created “new venues for conservative speech”, and that lawmakers who wanted to upend it were “well-meaning but mistaken”.

CEI has also defended Google in other realms. In a recent op-ed published in the Atlantic, a CEI senior fellow named Mario Loyola argued that the launch of a recent antitrust investigation into Google by 48 state attorneys general, led by the Texas attorney general Ken Paxton – a strong supporter of Ted Cruz – would not do anything to help the public.

A CEI spokesperson, who declined to comment on questions about Google, told the Guardian: “CEI is a nonprofit organisation that advocates free-market solutions to public policy issues. CEI’s research programmes and positions are developed independently by policy experts and reflect a longstanding, steadfast dedication to principles of economic liberty and limited government.”

When Google was asked about its support for CEI and groups like it, a company spokesperson said: “We sponsor organisations from across the political spectrum that advocate for strong technology policies. We’ve been extremely clear that Google’s sponsorship doesn’t mean that we endorse that organisation’s entire agenda – we may disagree strongly on some issues.”

Google employees have privately spoken out about the company’s support for some conservative groups. In a discussion with employees in March 2018 – a recording of which was heard by the Guardian – Adam Kovacevich, who at the time served as head of public policy at Google (he has since left the company), defended the company’s alignment with some conservatives.

He said he had been directed to forge the relationships after the 2016 election of Donald Trump. It reflected a view that the company was seen as too close to Hillary Clinton’s campaign and other Democrats.

The discussion took place after a controversy over Google’s sponsorship of the Conservative Political Action Conference (CPAC), the annual meeting of conservatives, where Google hosted a party.

To the consternation of many employees, its logo appeared on banners next to the NRA’s. In his opening remarks on the call, Kovacevich said it was important to build relationships not only with people in power “but also the people who influence them”.

“It can be hard sometimes to reconcile our business interests with our stated values, and finding that balance is something our team has to navigate really on a daily basis, and it has gotten more and more complicated,” Kovacevich can be heard saying in the recording.

While Google staff seemed to accept Google needed to forge ties across the political spectrum, the majority of the employees on the call expressed concern that the company was too far out of step with its values. The Wall Street Journal and Wired have previously reported on the meeting.

This year, Google did not sponsor CPAC. But big technology companies were frequently named – and lambasted – by conservative participants in their speeches. In one case, the rightwing provocateur James O’Keefe encouraged tech employees to secretly record colleagues in their offices in order to expose their alleged biases.

“We will equip you with a camera,” O’Keefe said. “If they’re lying, cheating, scamming, we’re going to find them, make them famous internet celebrities, expose them for all the world to see.”