If Al has incorporated himself, as AlGore LLC, they might be deductible as an "operating expense." But there's still the greater expense of buying them to begin with vs. the ~35% deduction to taxable income. Carbon offset credits are otherwise not deductible as a charitable contribution, to my knowledge. And if they were, there's still the greater cost to buy them vs. the charitable benefit to taxable income. And once sold, they are not-transferable unless re-sold to another party, in which case AlGore would lose the benefit of having purchased them to begin with.
Regardless, AlGore should LBE (lead by example) instead of "buying" a smaller carbon footprint for himself.
Another "man of the people" clueless of how the people actually live.
I will pay attention to the first Global Warming conference where the attendees arrive on bicycles. the Swiss confab, to say nothing of IPCC, involve well heeled honchos jetting in from all over the globe and leaving a "carbon footprint" exceeding that of most third world countries. Or hey, here's an idea, now that Algore has invented the internet, they could video-conference!