http://discovermagazine.com/2014/julyaug/13-journeys-to-the-center-of-the-earth

Oooh, all the science fiction I've read.... A little bit off-topic: when the Kola project ended, a few fundamentalist Christian classmates claimed that the "real" reason was because the Russians had broken into a chamber, heard thousands of human voices screaming in agony, and decided to seal the tunnel because they realized they had broken into Hell. I have my doubts about that.

So they're the ones responsible for global warming.