While that -might- be true, the question is whether the dollar, the RMB, the CAD, and every other currency have anything like the -direct- pollution cost of bitcoin, which my understanding is that they do not
I think the dollar undoubtedly has several orders of magnitude lower direct pollution costs, but also have several orders of magnitude higher indirect costs.
It's a pretty tangly web, so hard to know what to lump in as a comparison but in the superlative case consider: the federal reserve, many bank/FI departments tasked with securing and transferring money safely, auditing (public ledger has many benefits for transparency and reporting), money transfer industry, international relations, lobbyism, US military dominance, etc.
Bitcoin has zero employees, probably only thousands of people working on Bitcoin-interfaced systems. The network uses a large amount of electricity, but that's kind of it - there are few other costs to account for. All of those industries above collectively employ millions of people - should we account for only organizational energy consumption or do we also account for salaries and thus private energy consumption of all of the individuals necessary to support dollar hegemony?
I think it would be really interesting to find a number for "for each dollar in existence, how much is spent per year preserving the dollar's position as the global reserve currency?" How does this number compare to inflation? If it is greater than inflation, does that mean that dollar hegemony is unstable and its fall is inevitable?
Of the estimates I've read, it seems like BTC uses about 60% green energy. Which is about double the 'green-ness' of the broader energy economy, but it's still a significant amount of 'direct pollution' from carbon sources.