A Yale researcher set out to discover how much impact mega-wealthy corporations and individuals have had on the American public’s confusion about climate change.

The answer: Just as much as, if not more than, many have claimed—but, until now, could not measure objectively.

Justin Farrell combined several kinds of statistical, semantic, and network analysis—big data, in other words—to show that over the past two decades, climate contrarians funded by ExxonMobil and the Koch brothers’ family foundations have been the most successful at spreading talking points on uncertainty about climate-change science into the U.S. news media and political discussions.

That messaging has helped fuel the American public’s disbelief about climate change, despite the worldwide scientific consensus that global warming is a pressing and major threat to both humanity and the environment. The study was published Monday in the journal Nature Climate Change.

In a related study, published last week in the journal Proceedings of the National Academy of Sciences, Farrell found that Exxon and Koch funding of climate-contrarian entities played a major role in polarizing public discussion of climate change over the past 20 years.

The resulting public policy “climate wars” have helped hinder policies aimed at reining in greenhouse gas emissions.

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In early November, the attorney general of New York state subpoenaed Exxon for four decades of documents related to its climate research and messaging. The move was part of an ongoing investigation, reported InsideClimate News, into whether the oil giant lied to shareholders, federal financial regulators, and the public on the facts about global warming, as well as the risks it might pose to the corporation’s operations and value. Exxon has denied these allegations.

Research into public opinions about climate change “has tended to focus on the individual level, rather than the larger institutions and social networks that produce and disseminate contrarian information,” Farrell wrote in the summary of his findings in Nature Climate Change.

But this approach did little to account for the environment in which people formed their views. So Farrell set out to analyze that environment scientifically.

Among his evaluations, Farrell took texts from the “comprehensive social network made up of 4,556 individuals with ties to 164 organizations”—including think tanks, trade associations, and other groups—involved in “promulgating contrarian views.” He then used linguistic analysis techniques to compare them with the information in all verbal and written texts about climate change from three major news outlets (14,943 documents), all U.S. presidents (1,930 documents), and every occurrence on the floor of the U.S. Congress (7,786).

All the materials were created between 1993 and 2013.

Farrell found that the climate information most often echoed in these sources matched information spread by groups underwritten by ExxonMobil or the Koch family foundations, which are heavily invested in fossil fuel industries.

Their successes in swaying public policy on climate change, despite the lack of a factual basis for their claims, Farrell concluded, “have much broader implications for the privatization of science, the influence of corporate lobbying around scientific issues, and by extension, the increasing concentration of corporate wealth in the United States.”

Farrell’s findings highlight “how important it is for us, as a society, to be mindful of how science gets politicized,” said Harvard University political scientist Dustin Tingley. “It’s important to recognize that science is debated, and it is the responsibility of an informed public and an informed government to weigh various arguments against each other and eventually let objective and empirical evidence prevail.”

“There was a lot of careful work done” in the two studies, said Tingley, who has studied the role of public opinion in the climate change debate. “I don’t know this scholar, but I did not get a sense that his work was ideologically driven.”

Overheated rhetoric from any direction can undercut public understanding of complicated issues, he said. While Farrell’s research points to manipulation of news media and politicians by wealthy corporate elites, “we as a society need to be wary of manipulation in the other direction” as well, Tingley added.

This includes “recognizing the uncertainties that scientists do acknowledge” about the climate, such as just how much temperatures will rise and other conditions on Earth will change as a result over the coming decades.

“None of those scenarios paint a rosy picture,” Tingley said. “They’re all bad. But a doomsday scenario doesn’t paint the right picture either.”