Blockchain has the power to change our world for the better in so many ways. It can provide unbanked people with digital wallets, prevent fraud, and replace outdated systems with more efficient ones. But we still need this new and improved world to be one that we want to live in. The largest cryptocurrencies — Bitcoin, Bitcoin Cash, and Ethereum — require vast amounts of energy consumption to function. Last year, blockchain used more power than 159 individual nations including Uruguay, Nigeria, and Ireland. Unsurprisingly, this is creating a huge environmental problem that poses a threat to the Paris climate-change accord.