Not blockchain, Proof of Work. Emerging Proof of Stake blockchains have the potential to resolve this issue very soon.

And you know what, you can say the same about computers, that they have harmed the environment by using mass amounts of energy. Let's just switch them all off. And go back to riding horses, while we're at it, and dismantle all hospital equipment. You have to compare the amount of harm to the amount of help first, not to 0.