Telling their story before a Congressional committee for the first time, two former ExxonMobil scientists on Wednesday detailed how the oil giant turned its back on the research they did for the company 40 years ago on the looming threat of climate change.

They gave their testimony in Washington, D.C., just as Exxon went on trial in New York on allegations that it misled investors about climate change risks, underscoring how political and legal risks have dovetailed for a corporate giant that for years tried to sow doubt about the risks of carbon emissions.

Geochemist Ed Garvey described how Exxon shut down the carbon dioxide research program he worked on for the company from 1978 to 1983.

After the collapse of world oil prices in 1982, Garvey said, "they began to sell off things like lithium battery research and other divisions of Exxon research as they retrenched and focused solely on oil." One of the programs that was jettisoned was his project to monitor carbon dioxide concentrations in the air and ocean surface from a dedicated station aboard one of the company's supertankers.

"There was really a sea change ... where they had gone from this very broad-based, very future-looking energy company to becoming an oil company," Garvey told the hearing, held by the Civil Rights and Civil Liberties Subcommittee of the House Committee on Oversight and Reform.

After deepening the company's understanding of an environmental problem it suspected could harm its business, Exxon put its muscle behind efforts to manufacture doubt about the reality of global warming.

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"I cannot see into Exxon management's heart," said physicist Martin Hoffert, describing his distress at the company's newspaper ads in the 1990s contradicting the science on fossil fuel emissions' link to global warming. That work was his focus when he was a consultant to the company from 1981 to 1987.

"Whatever its intent—willful ignorance, stymying an effective response to preserve quarterly profits, or simply an incomprehensible refusal to incorporate their own world-class research and results into their business plans," Hoffert said, "what they did was wrong. They deliberately created doubt when their internal research confirmed how serious a threat it was."

The scientists' work for Exxon was featured in an award-winning 2015 investigation by InsideClimate News that explored the company's shift from climate research to climate denial and was mentioned in a video played as the hearing opened.

"In order to understand and confront the crisis we are facing, we must recognize the disastrous deception that brought us to the brink," committee chairman Rep. Jamie Raskin (D-Md.) said.

Rep. Alexandria Ocasio-Cortez (D-N.Y.), who has made climate change one of her signature issues as co-sponsor of Green New Deal legislation, showed a slide of a scientific chart produced by Exxon scientists.

A 1982 Exxon report titled "CO2 Greenhouse Effect: A Technical Review" included this chart, which shows projections for global temperature rise as the concentration of carbon dioxide in the atmosphere increases. Its projections for 2019 are very close to today's conditions.

"In 1982—seven years before I was even born—Exxon accurately predicted that by this year, 2019, the Earth would hit a carbon dioxide concentration of 415 parts per million and a temperature increase of 1 degree Celsius," said Ocasio-Cortez. "Dr. Hoffert, is that correct?"

"We were excellent scientists," Hoffert responded.

Climate Policies Gain Traction on Capitol Hill

What Exxon knew, and when the company knew it, will be crucial in the New York trial, where the state attorney general is arguing that the oil company defrauded investors by misleading them about the risks it faces from future climate regulations.

It also may prove to be important in shaping policy in Washington. Although the hearing did not focus on any legislative proposals to address climate change, the fact that they are being discussed on Capitol Hill was made clear by Republicans on the committee, who used their turns to bash proposals for a Green New Deal and carbon taxes.

On the other side of Capitol Hill, Sen. Chris Coons (D-Del.) and Sen. Mike Braun (R-Ind.) announced that they were launching a Senate Climate Solutions Caucus committed to building bipartisan support for climate solutions. There has been a similar effort for several years in the House, although only a few of the Republican members have signed on to any climate legislation. One of those, Rep. Francis Rooney (R-Fla.), just announced his retirement.

Coons is co-sponsoring a bill that would tax carbon emissions and rebate 70 percent of the revenue to households and devote the rest to energy infrastructure, job retraining for fossil fuel workers, and research and development. Braun has co-sponsored bills to boost nuclear energy and reduce greenhouse gas emissions from manufacturing.

Fossil Fuel Funding for Climate Opposition

The GOP invited as its witness to the hearing Mandy Gunasekera, a former Trump administration Environmental Protection Agency official who now runs a nonprofit advocacy group, Energy 45 Fund, which aims to tout Trump's environmental record. She is also an adviser to the CO2 coalition, a group fighting against action on climate change. "Our energy industry and the men and women in it are to be celebrated," Gunasekera said. "They've changed millions of lives for the better. Our successful energy industry is why we lead the world in environmental progress."

Ocasio-Cortez asked Gunasekera if she knew the CO2 Coalition was funded by fossil fuel interests like Koch Industries and the billionaire hedge fund manager Robert Mercer.

"I don't know the financing behind the CO2 coalition, but I'll say my engagement with them is not unwitting," Gunasekera said. "It is active and inspired and educated, because a lot of these folks are scientists who have long been diminished and ignored."

"Thank you for testimony that you are not unwittingly working for the Koch brothers," Ocasio-Cortez said, provoking laughter in the hearing room.

The exchange was especially relevant since one of the key charges leveled at Exxon during the hearing was that it funded some 40 think tanks and advocacy groups that worked for years to block meaningful U.S. action on climate change.

"They didn't just pollute the air," said Naomi Oreskes, a Harvard University science historian. "They also polluted the information landscape."

Read ICN's Pulitzer Prize-finalist series Exxon: The Road Not Taken