Exxon Mobil Corp. spent the last 40 years undermining public concern over climate change, even as its own scientists determined man-made global warming was real and a serious threat, according to Harvard University researchers writing in a peer-reviewed journal.

“Exxon Mobil contributed to advancing climate science — by way of its scientists’ academic publications — but promoted doubt about it in advertorials,” the Harvard researchers wrote in the journal Environmental Research Letters. “Given this discrepancy, we conclude that Exxon Mobil misled the public.”

The findings could add fuel to lawsuits brought against the world’s largest oil explorer by market value. New York’s attorney general is probing whether Exxon lied to investors and the public for almost four decades about the impact of climate change on profits. Exxon is one of the world’s largest sources of fuels responsible for climate change, producing 10 million gallons of gasoline and other fuels every hour of every day.

The researchers said Exxon has disagreed with their conclusion and said its statements on public policy and climate science “have always reflected the global understanding of the issue,” according to an opinion piece written by two of the authors and published Wednesday in the New York Times.

Exxon said it acknowledges climate change is a risk that requires action, and it dismissed the conclusions of the study, saying the researchers are looking for money.

“The study was paid for, written and published by activists leading a five-year campaign against the company,” Exxon said in an emailed statement. “It is inaccurate and preposterous. Rather than pursuing solutions to address the risk of climate change, these activists, along with trial lawyers, have acknowledged a goal of extracting money from our shareholders and attacking the company’s reputation.”

THE STUDY’S authors, Geoffrey Supran and Naomi Oreskes, both scholars of scientific history at Harvard in Cambridge, Massachusetts, reviewed 187 climate change communications issued by Exxon between 1977 and 2014. Their article, “Assessing Exxon Mobil’s climate change communications,” was published Wednesday.

While 83 percent of Exxon’s peer-reviewed scientific papers and 80 percent of its internal documents acknowledge climate change is real and human-caused, 81 percent of its advertorials expressed doubt over the issue, according to the research. Internal documents accepted the risk of stranded assets caused by climate change, while the advertorials did not.

The researchers point to the example of Exxon scientist Brian Flannery, who in 1985 helped the U.S. Department of Energy write a report acknowledging a scientific consensus on future warming trends caused by carbon dioxide emitted from fossil fuels. Despite that conclusion, company advertorials in 1997 and 2000 downplayed the human effect on climate change and instead promoted “natural variability” in the atmosphere, according to the research.

“Exxon Mobil’s scientists and executives were, for the most part, aware and accepting of the evolving climate science from the 1970s onwards, but they painted a different picture in advertorials,” wrote Supran and Oreskes.