They knew. They lied.
“As it turns out, “The Climate Deception Dossiers” shows that leading oil giants such as ExxonMobil, BP, and Shell—just like tobacco companies who buried and denied the threat of cancer for smokers—knew about the dangers of global warming and the role of carbon and other greenhouse gas emissions long before the public received warning from the broader scientific community. And what’s worse, of course, is not only that they knew—but how they have spent the last nearly thirty years actively denying the damage they were causing to the planet and its inhabitants.”
And, oh, what damage they have done. Climate change will be terrifying and deadly for a lot of the planet over the next 100 years.