The energy required to generate a vanity address is in the same order of magnitude as using air conditioner or electric heater for a few hours.
No crypto activity, not even Bitcoin mining, is a significant contributor to global warming. Bitcoin network might consume a lot of electricity, but it's still a small fraction of global electricity, and electricity itself is a small fraction of global greenhouse emissions.
Many operations contribute to global warming and they are not targets to be stopped by environmentalists or governments. Because they think such operations are contributing something necessary for societies.
So if those people change their minds and recognize that Bitcoin network is contributing good things for human and societies like freedom from central banks, governments, they will stop attacking Bitcoin in environmental and global warming aspects.
Bitcoin is clean.