Cryptocurrencies like Bitcoin have left their mark on the world, but not in the way most people predicted. In a typical Bitcoin mining operation, powerful banks of computers are dedicated to crunching out “blockchain” numbers and processing transactions. Nearly three-quarters of cryptocurrencies are mined in China, generating anywhere up to 10 million tons of carbon dioxide. Now that China is trying to cut back on the air pollution that often seems to swallow cities, the country’s chief planning regulator has unveiled a paper with a proposal to ban Bitcoin mining, saying it has “seriously wasted resources.” China has been considering a Bitcoin mining ban since last year when it asked local governments to encourage firms to quit the business by jacking up power prices and issuing stronger environmental rules. Now it seems they will take it a step further and outlaw bitcoin mining altogether. Whether it will wind up benefitting the planet, we’ll have to see. There’s always the possibility that miners will move their operations elsewhere.