Cryptocurrencies replacing a large portion of the legacy banking system would be a massive better for the environment, despite flawed the very successful propaganda campaign stating the opposite.
We've seen really smart people at MIT and other prestigious universities, put out really great analysis's of Bitcoin's mining energy usage. These showed a measurable, but paltry, energy usage, for Bitcoin's market cap near one of US's largest banks.
These smart people always went on to make the same really dumb assumption and error, seemingly on purpose. They assumed that this mining energy usage would grow with increased Bitcoin usage. Even worse, they frequently make the wild assumption this would grow lineally with usage. This is the type of overt assumptions data analyst are trained to identify and avoid. This makes you suspicious of what motivated this same coordinated disinformation to be included in so many research papers. It has been a super successful propaganda false talking point which crypto industry attacks have narrowly focused on.
Of course, proof of work mining doesn't work this way and all of Bitcoin's mining at fully capacity, could conceptually be done with one single computer, it just wouldn't have the decentralized consensus security. There is no relationship between transaction volume or size and the required effort. Conceptually, today's mining energy usage is the highest it will ever be. The auto-adjusting mining difficulty ensures that mining energy, again conceptually, never grows, but only reduces as increases in mining effort, naturally push less energy efficient mining hardware out of being profitable. Of course, market value, mining hardware supply, situational energy/infrastructure costs, and the ability to mine at a immediate profit loss for various reasons, impact the real-world reality of this in-built concept.
I suggest this mining environmental impact is massively dwarfed by the 7,037 commercial US banks, (just that are FDIC insured/supervised) each with 1 to thousands of physical buildings, as well as their 2 million employees (at the very least) sputtering to work daily. Not to mention their vast infrastructure needs, supporting services, and an extensive entire industry of regulatory oversight.
there doesn't seem to be anything here