During an interview with The Nation, Jane Mayer, author of Dark Money: The Hidden History of the Billionaires Behind the Rise of the Radical Right, explained:
It’s a curious story, because the Kochs are not religious. They don’t care about social conservatism. They call themselves libertarians. They certainly are not aligned with Pence on these moral issues, on his hatred of abortion. What do they have in common? It turns out that in 2009
Mike Pence started doing favors for the Kochs. They were tremendously powerful, but they were really worried that some legislation was going to pass that would tax carbon emissions. The Kochs have a huge fossil-fuel company and it would have hurt their bottom line tremendously.
Mike Pence took up their cause. He campaigned, he pushed and wheedled, and he took a pledge that the Koch organization had created and he got many of his colleagues in the House to sign onto it, saying they would pass no legislation to stop global warming that would require spending a cent of government money. He succeeded in killing the legislation, and from there on out, in aligning the Republican party against doing anything about climate change, unlike almost any other political organization in the world. To be fair, Pence opposed doing anything on global warming also for his own ideological reasons—he had doubted the reality of climate change before the Koch pledge. But Koch Industries has rewarded him ever since. That’s when they began to push him to run for president.