Proof of Stake cryptocurrencies are the least energy-intensive: Ethereum (since 2022), Solana, Cardano and Polygon have a carbon intensity close to zero, of the order of 0.003 tonnes of CO2 per million euros, a factor of 10,000 below Bitcoin. Stablecoins such as USDC or USDT, issued on these chains, also have a negligible footprint. A low footprint does not, however, make a crypto asset a useful investment for the climate.
Read the source article: Bitcoin carbon footprint: 33 tCO2e/year per million euros held