WASHINGTON – Decades of climate denialism by the oil industry forestalled meaningful government measures to reduce the severity of climate change, several environmental activists said Wednesday at a House subcommittee hearing.

As the oil industry takes great advantage of speeding up its production of fossil fuels, oil giants like Exxon have continued to fund climate denial organizations.

Rep. Jamie Raskin, chair of the House Oversight and Government Reform’s civil rights subcommittee, said ExxonMobil knew that its fossil fuel production damaged the climate but funded climate denial groups to slow down efforts to reduce greenhouse gas emissions.

Former ExxonMobil scientist Ed Garvey testified that the oil company conducted climate research with several academic institutions to “earn its place at the table,” but in the early 1980s, it canceled this program as oil prices dropped.

“In the 1970s, Exxon knew that carbon dioxide emissions caused a potential problem,” he said.

Naomi Oreskes, an earth and planetary sciences professor at Harvard University, testified that ExxonMobil alone funded 39 “think tanks” and has spent upwards of $2 billion on lobbying” to deliberately mislead the public on the reality of climate change.

“This is a classic example of the denialist tactics,” she said.

Mustafa Ali, vice president of the National Wildlife Federation, said minority groups are disproportionately hurt by oil companies.

“Fossil fuel plants are disproportionately located in communities of color,” he said. “They are suffering from the health impacts of the oil industry, such as asthma, cancer, and premature death.”

Rep. Jimmy Gomez, D-Calif., called climate change as a civil rights issue and said the fossil fuel industry’s efforts to thwart efforts to slow climate change are a “distortion of democracy.”

Also Wednesday, Democratic presidential candidate Sen. Bernie Sanders expressed his concern on Twitter. “When I am president, we will launch a criminal investigation of the fossil fuel corporations and their executives who knowingly created the climate crisis,” he tweeted.