Use of the cryptocurrency Bitcoin causes approximately 22 megatons in CO2emissions each year, an amount comparable to the total emissions of entire countries such as Jordan and Sri Lanka, Gregory Barber reported for Wired in June 2019. The Wired article reported the findings of a 2019 study conducted by researchers at the Technical University of Munich on the energy consumption of bitcoin mining. “Coal is fueling Bitcoin,” Christian Stoll, the leader of the research team, told Wired. “The question is how to prevent it.”
Barber’s Wired report also noted that a previous study estimated that, if Bitcoin followed the pattern of other widely adopted technologies, it would produce “enough CO2 emissions to push warming above 2°C within less than three decades.” Barber noted some have said such estimates are inflated, because Bitcoin mining increasingly uses cheap renewable energy, like hydropower.
The energy costs of Bitcoin mining are difficult to estimate, because it involves “a global network of  machines racing to solve complex math,” Barber wrote. It’s difficult to assess the types of machines in use, where they’re located, and how they are powered.
Stoll’s research team at the Technical University of Munich was able to take a “more granular” approach to determining the energy costs of Bitcoin mining: When three Chinese mining hardware manufacturers filed for initial public offerings, “they disclosed a trove of technical details and data about market share that’s usually kept under wraps,” Barber wrote. By examining this data, the researchers were able to determined what kind of equipment was being used and where, making their estimates of energy consumption more precise.
Stoll told Wired that the full carbon footprint of cryptocurrencies extends beyond Bitcoin’s estimated 22 megatons of annual CO2 emissions. Ethereum, Monero, zCash, and other cryptocurrencies depend on similarly energy-intensive systems, meaning that the total emissions figure for all cryptocurrencies “could roughly double,” Barber reported. As Alex Hern wrote in a January 2018 report for the Guardian, “the fundamentally wasteful nature of bitcoin mining means there’s no easy technological solution coming.”
Because the carbon footprint of Bitcoin mining is so big, Stoll believes it may be “worth discussing the possibility of regulating cryptocurrency mining in regions where power generation is especially carbon-intensive. To improve the ecological balance, one possibility might be to link more mining farms to additional renewable generating capacity.”
As of June 2019, CNN and CBS News are the only corporate media that appear to have reported on the issue of cryptocurrencies and carbon dioxide emissions.
Source: Gregory Barber, “Bitcoin’s Climate Impact Is Global. The Cures Are Local,” Wired, June 19, 2019, https://www.wired.com/story/bitcoins-climate-impact-global-cures-local/
Student Researcher: Elsa Denis (University of California, Davis)
Faculty Evaluator: Mickey Huff (Diablo Valley College)