Researchers from the Technical University of Munich and the Massachusetts Institute of Technology took a look at how much energy was consumed by computers used to generate bitcoins and process transactions. Their conclusion:
in late 2018, the entire bitcoin network was responsible for 22-22.9 million tons of CO2 per year — similar to a large Western city or an entire developing country like Sri Lanka. Total global emissions of the greenhouse gas from the burning of fossil fuels were about 37 billion tons last year. The researchers said about 68% of the computing power used to generate, or mine, bitcoins is in Asia, 17% is in Europe and 15% is in North America. [Fortune/AP]
The whole study is worth reading. (link)