"Climate change was a huge thing at the time," says geophysicist Edward Garvey, who worked for Exxon from 1978-1983. "Exxon researched in all directions, CO2 emissions, storm development, permafrost melting. And then, overnight, all research programs were discontinued. That's so frustrating."

Then, the company did exactly the opposite. They commissioned counter-studies, which were widely disseminated via lobby groups. They deliberately financed studies to discredit their own results and tried to explain climate change through sunspots or denied it altogether. They stressed statistical errors and uncertainties in research. The same tactics climate change deniers employ today.

"For me, this is the biggest scandal in human history," explains Carroll Muffett, the Chairman of the Center for International Environmental Law in Washington, an NGO dealing with environmental law.

Meanwhile, two public prosecutors and several counties in the United States have started investigations against Exxon and other oil companies for deliberately misleading the public on the subject of climate change. But are similar false arguments also being used by climate change deniers in Germany?