Carbon offsetting is different from indulgences, because the offset is actually calculated and verifiable. You pay some money to cover some materials and labor, that labor will result in x amount of carbon-dioxide being sequestered over a certain amount of time. You can actually go and research this stuff if you're so skeptical. There are actual explanations for how everything works, so it is in absolutely no way like a catholic indulgence, where you never actually know if the money you're spending is doing anything. You can actually go on the web and find answers to all your questions. Yes, I mean you, specifically.