The New York attorney general is investigating whether Exxon Mobil lied to the public — and investors — about the risks to the environment and its business posed by climate change, according to a report Thursday from The New York Times.

The Times reports that the attorney general issued a subpoena on Wednesday. An Exxon Mobil spokesman on Thursday told the paper that "the company had received the subpoena and was still deciding how to respond."

The subpoena comes on the heels of a pair of investigations — from InsideClimate News and the Los Angeles Times — revealed that by the early 1980s, Exxon’s scientists and top management already understood the significance of climate change and were even making plans to adapt to it.

“As far back as 1977, everybody from rank-and-file scientists at Exxon all the way up to the executive suites knew about climate change and the emerging science, which was then called the greenhouse effect,” says Neela Banjaree of InsideClimate News. “They understood very clearly that it was a significant risk to civilization. They said that rising temperatures could destroy agriculture in many places and could shift precipitation patterns.”

“Even more interestingly, from what we can tell, Exxon was probably the only major company that launched its own, in-house, very rigorous climate science research effort,” Banjaree says.

Exxon knew that if the science was correct, at some point governments would take action to reign in emissions of carbon dioxide, according to the new report. “They felt that the best way to shape policy was to do really good science, to be taken seriously in order to have a seat at the table,” Banjaree says.

At the time, the science community was still struggling to understand the role the oceans played in absorbing the carbon dioxide that was being emitted by the use of fossil fuels. So Exxon outfitted a new supertanker, the Esso Atlantic — one of the biggest in the world — with specially made equipment to gather samples of air and ocean water along its route from the Gulf of Mexico to the Persian Gulf to see how the oceans were absorbing CO2.

“They felt that if they did this over a period of time they could get a regular, continuous reading and it would help scientists understand the role that the oceans played,” Banjaree says.

Exxon scientists were proud of their contribution. Former Exxon scientist Edward Garvey said this about their research in a short video produced by InsideClimate News and Frontline:

"We were generating what we thought was state-of-the-art information. We were doing science that we didn't think in any way, shape, or form would be questioned. There was no questioning that the atmospheric carbon dioxide was increasing, that atmospheric carbon dioxide was going to change the climate in some fashion. The question was how fast, how much, and what kind of impacts would it have overall to the planet."

All of this information was presented to Exxon's top executives — the chairman, the CEO, and the senior vice presidents. Exxon's scientists and managers from Exxon Research and Engineering regularly sent detailed updates to senior vice presidents who were members of the management committee about the research, Banjaree says.

“Something like the tanker project, which required coordination across many different divisions of Exxon, could only occur if you had someone from the senior VP level sign off on it, former Exxon officials told us,” she says.

But by 1989, something had changed within the company. Exxon co-founded an organization called the Global Climate Coalition (GCC), which, while it may sound ‘green,’ was, in fact, a group of fossil fuel companies and major manufacturers that were working to stall action on climate change under consideration by the UN, Banjaree says.

And by 1996, Exxon CEO Lee Raymond, who was trained as a chemical engineer, was making public statements that contradicted his own’s company scientific information: “Proponents of the global warming theory say that higher levels of greenhouse gases are causing world temperatures to rise, and that burning fossil fuels is the reason. But scientific evidence remains inconclusive as to whether human activities affect the global climate,” Raymond declared.

Nearly 20 years after Exxon scientists started warning of the possibility of greenhouse gas emissions causing world temperatures to rise and disrupt the climate, why did the CEO say this?

“That's the question that everybody has to unearth,” Banarjee says. “Why did the shift occur? ... We haven't got a satisfactory answer from Exxon about this: Why did Exxon shift its position from doing rigorous, peer-reviewed science in order to have a constructive voice in policymaking, to founding the GCC and having its chief executive cast doubt on climate science?”

The Los Angeles Times and the Energy and Environmental Reporting Project at Columbia University’s Graduate School of Journalism have been publishing their own series that looks into the discrepancy between Exxon's external and internal dialogue on climate disruption. Their reporting focuses specifically on the company’s contradictory public and private stands about melting ice in the Arctic.

Banjaree says this investigation fills in some missing information from her own, but addresses the same puzzling change in the company’s position on global warming.

“[Here] you have Lee Raymond casting doubt publicly on the fact that climate change might be happening, but internally Exxon scientists are looking at climate change and greater melting in the Arctic and how that might open up access to resources, oil and gas resources in the Arctic,” Banjaree says.

Not surprisingly, Exxon — now Exxon Mobil — takes issue with the recent investigations.

“We very much disagree with both of those reports,” says Ken Cohen, vice president of public and government affairs for Exxon. “In fact, nothing could be further from the truth than what is being claimed in those two stories.”

Cohen acknowledges that in the late 1970s, Exxon scientists began studying the impact of CO2 emissions on climate. He disputes, however, reporting that “would seem to indicate that research stopped at some point."

“In fact, our scientists have participated in every UN climate assessment beginning in 1988,” Cohen says. "Our scientists have contributed over 50 papers that were reviewed by the collective body of scientists studying this very complex subject. In addition, we've been part of creating some of the most sophisticated modeling programs at research institutions in the country. Our scientists have been a consistent part of the scientific inquiry.”

Cohen also disputes the reports’ claims that Exxon sought to cast doubt publicly on climate change while using its own internal science to shape future company decisions.

“Our participation in the discussions on public policy response pretty much mirrors the IPCC findings during the relevant period,” Cohen maintains. “That is, our positions evolved over the period 1988 to the present time as the science evolved.”

Lee Raymond’s 1996 speech is consistent with the overall scientific consensus at the time, Cohen insists.

“Remember, the scientific view and understanding of this issue has evolved as one would expect it to do, the understanding would evolve over time,” he says.

Meanwhile, some members of Congress, including Vermont senator and Democratic presidential candidate Bernie Sanders, are asking whether the published stories show that Exxon Mobil broke the law when it spoke out against the science it had itself helped to pioneer.

Senator Sanders has called on the Justice Department to launch a criminal investigation. He wrote, “These reports, if true, raise serious allegations of a misinformation campaign that may have caused public harm similar to the tobacco industry’s actions — conduct that led to racketeering convictions.”

Sanders added, “It appears that Exxon knew its product was causing harm to the public and spent millions of dollars to obfuscate the facts in the public discourse.”

Two Democrats in the House of Representatives, Rep. Mark DeSaulnier and Rep. Ted Lieu, have also called on the Justice Department to investigate Exxon’s actions.

DeSaulnier says the revelations in the articles really took him by surprise. “I’ve been in politics a long time. I’ve got four refineries in the county that I represent. So I’ve dealt with the petroleum industry. I was on the California Air Resources Board for 10 years. So I’m not unfamiliar with them — but I was shocked,” DeSaulnier says.

This story is based on an interview that aired on PRI's Living on Earth with Steve Curwood.