Every country has a different environmental footprint associated with Bitcoin. It’s largely dependent on its energy sources, with the U.S. and China having the largest Bitcoin mining footprints.
As bitcoin and other cryptocurrencies have grown in market share, they’ve been criticized for their heavy carbon footprint. Cryptocurrency mining is energy-intensive. Mining also has massive water and land footprints, according to a new study that is the first to detail country-by-country environmental impacts of bitcoin mining. It is the foundation for a new United Nations (U.N.) report on bitcoin mining, published today.
The study reveals how each country’s mix of energy sources defines the environmental footprint of its bitcoin mining and highlights the top 10 countries for energy, carbon, water and land use. The work was published in Earth’s Future, which publishes interdisciplinary research on the past, present and future of our planet and its inhabitants.
“A lot of our exciting new technologies have hidden costs we don’t realize at the onset,” said Kaveh Madani, a Director at United Nations University who led the new study. “We introduce something, it gets adopted, and only then do we realize that there are consequences.”
Madani and his co-authors used energy, carbon, water and land use data from 2020 to 2021 to calculate country-specific environmental impacts for 76 countries known to mine Bitcoin. They focused on Bitcoin because it’s older, more popular and well-established compared to other cryptocurrencies.
Madani said the results were “very interesting and very concerning,” partly because demand is rising quickly. But even with more energy-efficient mining approaches, he said that if demand continues to grow, so will mining’s environmental footprints.
Electricity and Carbon
If bitcoin mining were a country, it would be ranked 27th in energy use globally. Overall, the study found that bitcoin mining consumed about 173 terawatt hours of electricity in the two years from January 2020 to December 2021, about 60 per cent more than the energy used for bitcoin mining in 2018-2019. Bitcoin mining emitted about 86 megatons of carbon, mainly because of the dominance of fossil fuel-based energy in bitcoin-mining countries.
The environmental impact of bitcoin mining fluctuates along with energy supply and demand in a country. When energy is inexpensive, the profitability of mining Bitcoin goes up. But when energy is expensive, the value of Bitcoin must be high enough to make the cost of mining worth it to the miner, whether it’s an individual, a company or a government.
China, the U.S. and Kazakhstan had the largest energy and carbon footprints in 2020-2021.
Globally, bitcoin mining used 1.65 million litres of water in 2020-2021, enough to fill more than 660,000 Olympic-sized swimming pools. China, the U.S. and Canada had the largest water footprints. Kazakhstan, Iran, the U.S. and China have suffered from water shortages, which were also in the top-10 list for water footprint.
“These are very, very worrying numbers,” Madani said. “Even hydropower, which some countries consider a clean renewable energy source, has a huge footprint.”
The study analyzed land use by considering the area of land affected to produce energy for mining. The land footprint of server farms is negligible, Kaveh said. The global land use footprint of bitcoin mining is 1,870 square kilometres, with China’s footprint alone taking up 913 square kilometres. The U.S. land footprint is 303 square kilometres, likely growing while China’s is shrinking.
Most impacted countries
China and the United States, which have two of the largest economies and populations in the world, take the top two spots across all environmental factors. A mix of other countries make up the other 8 spots in the top 10. Kazakhstan, Malaysia, Iran and Thailand — countries to which servers are outsourced and, in some cases, where the government subsidizes cryptocurrency mining — appear as well. Canada, Germany and Russia have some of the largest footprints across all categories. Kaveh noted that each country engaged in large-scale bitcoin mining affects countries worldwide by their carbon emissions.
However, the benefits of Bitcoin mining may not accrue to the country or the individuals doing the work. Cryptocurrency mining is an extractive and, by design, difficult-to-trace process, so the geographic distribution of environmental impacts cannot be assumed to be a map of the biggest digital asset owners.
“It’s hard to know exactly who benefits from this,” Madani said. “The issue now is who is suffering from this.”
Already, some countries have potentially seen their resources impacted by cryptocurrency mining. In 2021, Iran faced blackouts. The government blamed bitcoin mining for excessively draining hydropower during a drought and periodically banned the practice.
China in June 2021 banned bitcoin mining and transactions; other countries, such as the U.S. and Kazakhstan, have taken up the slack and had their shares in bitcoin increase by 34 per cent and 10 per cent, respectively.
Madani said the study is not meant to indict Bitcoin or other cryptocurrency mining. “We’re getting used to these technologies, and they have hidden costs we don’t realize,” he said. “We want to inform people and industries about these costs before it’s too late.”
About the paper
This study is published in Earth’s Future, an open-access journal. View and download a PDF of the study here. The authors’ policy-related comments do not necessarily reflect the views of the American Geophysical Union.
This study provides the peer-reviewed data serving as a foundation for the U.N. report, “The Hidden Environmental Cost of Cryptocurrency: How Bitcoin Mining Impacts Climate, Water and Land,” published on the same day as this study. The report includes additional data not peer-reviewed by Earth’s Future. View the U.N. press release here.
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