I validated a mere 2 transactions on OpenSea (just to put up an account and items for sale, not creating any value as such) and that generated several tons of CO2 according to https://carbon.fyi/.

There is a lot of hype around this, and for every Beeple seeling ridiculous amounts of money from their art, how many smaller artists & tinkerers end up releasing quantities of CO2 for no value created in exchange (i.e. NFTs sitting on a virtual shelf which likely no one is ever going to buy - like mine! - but have had a real environmental impact).

NFTs feel like a gold rush, but there's more to it.