(Reuters) - The U.S. electric industry knew as far back as 1968 that burning fossil fuels might cause global warming, but cast doubt on the science of climate change and ramped up coal use for decades afterward, an environmental watchdog group said on Tuesday.

A gas flare burns at a fracking site in rural Bradford County, Pennsylvania January 9, 2012. REUTERS/Les Stone

The California-based Energy and Policy Institute, which opposes fossil fuels, cited documents it obtained. It said its research mirrors reporting conducted by InsideClimate News about Exxon Mobil’s early understanding of climate change, which triggered an investigation by New York’s Attorney General.

The documents released by the EPI showed the Edison Electric Institute industry group was warned at its annual convention in 1968 by a member of then-President Lyndon Johnson’s administration that carbon emissions from fossil fuels could change the climate and trigger “catastrophic effects.”

The electric industry’s research organization, the Electric Power Research Institute, then began studying the issue in the 1970s and produced its own research that included warnings of rising CO2 levels, temperatures, and sea levels, according to the EPI, which provided links to documents supporting its findings.

By 1988, the EPRI produced a report that concluded “there is a growing consensus in the community that the greenhouse gas effect is real,” the EPI said.

However, “rather than warn the public”, the electric industry made long-term investments in coal-fired generation and joined energy industry efforts to block climate regulations - including by lobbying, funding advertisements, and funding scientists skeptical about climate change, the EPI said.

There is now overwhelming consensus among scientists that fossil fuel emissions cause global warming. Nearly 200 nations agreed in Paris in 2015 to work together to cut emissions to keep warming in check - although President Donald Trump has since decided to exit the accord because, he says, it would cost the U.S. economy trillions of dollars without benefit.

The Edison Electric Institute, which represents electric companies in all 50 states, declined to comment directly on the EPI’s findings, but said the industry had already reduced emissions of the gases blamed for causing climate change.

“The electric power industry has reduced carbon emissions by 25 percent below 2005 levels as of the end of 2016,” said Jeff Ostermayer, an EEI spokesman.

An official at the EPRI did not respond to a request for comment.

U.S. coal use peaked more than a decade ago. Many utilities have in recent years turned away from coal toward cheaper natural gas - as well as solar and wind - contributing to a steep decline in carbon emissions.

Dozens of utilities surveyed by Reuters earlier this year said they would continue to move away from coal despite efforts by the Trump administration to revive the coal industry.

The EPI said some in the industry were still misleading the public and investors on climate change. It named Georgia-based Southern Co, whose CEO Thomas Fanning told CNBC in March that he did not believe scientists had proven that CO2 is the main driver of climate change.

A Southern spokesman said “climate change is a challenging issue,” the company had cut carbon output 27 percent from 2005 levels, and was “meeting or exceeding all environmental regulations across our system.”