FACT: oil is not a carbon byproduct of ancient fossils, it's a carbon byproduct of ancient deposits of Roger's body hair. He's immortal, but every once in a while, he loses a bet. Roger is solely responsible for global warming, but not in the way you're thinking; it has nothing whatsoever to do with Vindaloo, and everything to do with last time he lost a bet and had to shave his back. Uncertain of how to handle the massive biohazard threat posed by the trimmings, the DOT lit them on fire in a fiasco reminiscent of Oregon's exploding whale but on a monumental scale, effectively tripling global carbon emissions and sending the planet spiraling into ecological disaster.
The only reason he hasn't done it again is because he enjoys the alternate explanations the White House comes up with. The only reason the White House comes up with alternate explanations is because he's kept every administration since Herbert Hoover in cringing obsequiousness to his every whim with the judicial application of mind-lazors.