In testimony before Congress Thursday, top executives from some of the world’s largest oil and gas companies insisted that their firms had never misled the public about the science or severity of climate change.

It was the first time the executives have been confronted while under oath with the industry’s past efforts to cast doubt on climate science and funding of groups that peddled climate denial. But the hearing yielded little new from the executives, each of whom acknowledged that fossil fuels are driving climate change and promoted their efforts to reduce corporate emissions.

“Any suggestion that Chevron is engaged in an effort to spread disinformation and mislead the public on these complex issues is simply wrong,” said Mike Wirth, Chevron’s chief executive, in his opening statement.

House Democrats who summoned the executives characterized the hearing as a watershed moment for the public. Companies that testified included ExxonMobil, Chevron and the American subsidiaries of Royal Dutch Shell and BP. The chiefs of the American Petroleum Institute and the Chamber of Commerce also testified. All of the witnesses testified remotely.

Rep. Carolyn Maloney (D-N.Y.), the chairwoman of the Committee on Oversight and Reform, opened the hearing by saying that Exxon’s top executives were told in the 1970s and 1980s by their own scientists that fossil fuel emissions were warming the climate, a revelation first reported in 2015 by Inside Climate News and the Los Angeles Times.

“Exxon and other big oil companies had the opportunity to tell the truth and lead the way to find alternative energy sources,” she said, “but instead doubled down on fossil fuels,” and worked through a network of think tanks to play up scientific uncertainties and undermine national and global efforts to limit emissions.

The hearing was the beginning of an investigation that the committee has launched on the topic. Last month, the committee sent letters to each of the companies requesting documents about their “role in supporting disinformation and misleading the public to prevent action on the climate crisis.”

At the close of the hearing, Maloney said none of the companies had adequately complied with the request and that she would issue subpoenas for documents, including internal communications and board materials showing corporate strategies on climate change.

Maloney and other Democrats had framed the hearing as similar to the hearing in the 1990s in which tobacco executives testified and initially denied that cigarettes were addictive or that there was conclusive evidence that they caused cancer. Like the tobacco companies, the oil companies now face a wave of lawsuits brought by cities and states over their alleged misstatements.  

Some climate advocates and Democrats have maintained that the oil industry has continued to obfuscate, if in more subtle ways. All the companies support the Paris Agreement, and each affirms the basics of climate science. Each of the major oil companies has also committed to reducing their own direct emissions, and they have run extensive advertising about their investments in low-carbon technologies like carbon capture and storage and biofuels.

But many advocates say those advertisements are misleading—the low-carbon investments remain a fraction of overall spending by the major oil companies, particularly Exxon and Chevron. And the companies have all continued to support at least some groups, like the American Petroleum Institute, that are currently fighting against key components of the climate legislation moving through Congress.

The committee’s investigation was launched after an Exxon lobbyist, who has since left the company, was captured on video in a sting by Greenpeace UK talking about the company’s lobbying. The lobbyist, Keith McCoy, thought he was speaking to a headhunter, and acknowledged the company’s past use of “shadow groups” to fight climate action. He also characterized Exxon’s support of a carbon tax as a “talking point,” saying the company could endorse it knowing it had little support in Congress or likelihood of being enacted. Exxon has said the characterization was inaccurate and that McCoy’s comments don’t represent the company’s positions.

The committee’s Republican members said the hearing was an attempt to distract from rising energy prices, inflation and other issues. Several argued that the nation should be promoting oil and gas production to help feed global demand, rather than ceding that production to Russia and other countries. They also criticized the committee for basing an investigation on material obtained deceptively by Greenpeace UK.

Early in the hearing, Maloney pressed Exxon Chief Executive Darren Woods on the company’s record. She read from internal reports in which Exxon scientists reported agreement that carbon dioxide emissions from fossil fuel combustion were warming the climate, and contrasted them with public statements by the company’s then-chief executive, Lee Raymond, casting doubt on that very science.

“Do you agree there is an inconsistency,” she asked Woods.

But Woods refused to acknowledge any discrepancy, arguing it was consistent with the full report. Later, Rep. Peter Welch (D-Vt.) asked whether Exxon had disclosed any of these internal findings to shareholders, but Woods refused to answer directly, saying instead that the science was all publicly available.

Again and again, executives were pressed on their organizations’ roles in campaigns to spread doubt and to oppose climate action, and each time, the executives evaded firm answers, saying the episodes in question had occurred decades ago and that they had no specific knowledge of the details.

Rep. Ro Khanna (D-Calif.) focused his questions on the present. Both Shell and BP have said they support electrical vehicle incentives and a proposed fee on methane emissions, but both are still members of the American Petroleum Institute, which has strenuously opposed both efforts. Khanna asked David Lawler, chief executive of BP America, and Gretchen Watkins, president of Shell Oil, if they would tell the institute to stop, but neither took the opportunity to do so.

The committee also released a report it had conducted on industry lobbying, showing that the companies and trade groups had devoted hardly any of their vast lobbying resources towards promoting the Paris climate agreement or a carbon tax, despite their stated support of both.

Some lawmakers noted that while Shell and BP, both of which are based in Europe, have committed to reducing their oil and gas output over time, the U.S. companies Exxon and Chevron remain committed to maintaining or even expanding their production.

When the hearings came to a close, Maloney said that while she was grateful to hear the executives acknowledge the severity of climate change and the role their products play in driving it, “I was disappointed that we heard much of the same denial and deflection we have heard before.” She added that “Today’s witnesses refused to take responsibility for Big Oil’s decades-long disinformation campaign,” and pledged that the committee would continue its investigation as a result.