For the past 50 years, Americans have been told that natural gas was the clean fossil fuel, a climate-friendly choice for heating homes and cooking meals. But according to a new investigation, major oil and gas companies promoted that message while knowing all along that gas was a major source of air pollution and a contributor to climate change.

A report released today by the Center for Climate Integrity shines a light on a decades-long public relations campaign by oil and gas companies to re-brand natural gas as “clean energy,” despite internal knowledge dating back to the 1960s that methane emissions from natural gas posed climate risks.

Drawing on newly discovered industry documents, the report shows that gas companies deceived Americans by borrowing tactics from the tobacco industry to shape public opinion. It then funded favorable research, warded off regulation, and supported the expansion of gas use in American homes — a campaign whose effects persist today.

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Around 1970, oil and gas companies faced a growing problem. Internal polling showed Americans viewed natural gas as a polluting fuel, just as environmentalism was gaining political traction and scientific evidence about gas emissions was mounting.