China’s crackdown on cryptocurrencies upended the world of Bitcoin last year, triggering a mass exodus of “miners” — who use power-hungry computers to mine, or create, new Bitcoins — to new locations around the world. Now, research has found that the exodus likely made cryptomining, which already uses more electricity than many countries , even worse for the climate. According to the peer-reviewed study, which appears in the journal Joule, the Bitcoin network’s use of renewable energy sources like wind, solar or hydropower dropped from an average of 42 percent in 2020 to 25 percent in August 2021. One likely...