recently, I read some articles about the energy use of Bitcoins, which is devastating.
Did you know, that running the system of Bitcoins needs almost the equivalent of energy of the Netherlands?  Netherland ranks on the 32nd place in the list of the wold’s electricity consumption.  Just imagine we would give up on Bitcoins, we would be able to supply CO2 neutral electricity for the entire state of Netherlands. Alone the word’s energy production out of biofuel and waste could power the bitcoin network 6 times. 
Unfortunately, most bitcoin operations are not run by some kind of renewable energy. The majority of the operation center are located in county where energy is cheap. 60% – 70% of Bitcoins are currently mined in China, where energy supply comes predominantly from coal-fired power station, generating huge CO2 emissions. Although there is a portion of mining centres run by renewable energy resources, the International Agency of Energy (IAC) estimates that bitcoins generate 0.03-0.06% of global energy-related CO2 emissions per year. 
During her TEDx Talk, Tara Shirvani explains how the huge energy demand is generated and introduces an option how CO2 emissions through blockchain can be mitigated.
As Tara explains, Bitcoins are only part of the entire blockchain operations, which are the basis of the massive energy consumption. There are a lot more applications running on blockchain, which will increase the energy use in the future.
I think everyone investing in bitcoin is automatically increasing his/her CO2 footprint every they make a transaction. Sadly, most of the people dealing with bitcoin do not even know their impact.
1. Country Ranking. 2021 [cited 2021 03.01.2021]; Available from: https://cbeci.org/cbeci/comparisons.
2. Country Comparison: Electricity – Consumption. [cited 2021 03.01.2021]; Available from: https://www.cia.gov/library/publications/resources/the-world-factbook/fields/253rank.html.
3. Cambridge Bitcoin Electricity Consumption Index. 2021 [cited 2021 03.01.2021]; Available from: https://cbeci.org/mining_map.
4. Kamiya, G. Bitcoin energy use – mined the gap. 2019 [cited 2021 03.01.2021]; Available from: https://www.iea.org/commentaries/bitcoin-energy-use-mined-the-gap.