Bitcoin’s Impacts

In April of 2011, the price of one bitcoin was $1; this April it reached an all-time high of almost $65,000, and as of this writing each one is worth approximately $48,000. Because some bitcoin investors have become millionaires overnight, more and more people are intrigued by the possibility of striking it rich through investing in cryptocurrencies like Bitcoin. But Bitcoin’s rising popularity may make it impossible for the world to stave off the worst impacts of climate change, because the energy consumption of this cryptocurrency is enormous and its environmental implications are far-reaching. To understand Bitcoin’s environmental impacts, we first need to know what it is and how it works. What is Bitcoin? A cryptocurrency is a virtual medium of exchange that exists only electronically; it has no physical counterpart such as a coin or dollar bill, and no money has been staked to start it. R.A. Farrokhnia, Columbia Business School professor and executive director of the Columbia Fintech Initiative, said, “It’s a marketplace and as long as people are willing to assign value to it, then that’s it.” Bitcoin, the largest cryptocurrency in the world, accounting for more than half of all cryptocurrency, can be used to buy cars, furnishings, vacations and much more. This month, the world’s bitcoins were worth $903 billion. Cryptocurrencies are decentralized, meaning that there is no central authority like a bank or government to regulate them. The advantage of this is that there are no transaction fees, anyone can use it, and it makes transactions like sending money across national borders simpler. While transactions are tracked, the people making them remain anonymous. This anonymity and lack of centralized regulation, however, means that tax evaders, criminals, and terrorists can also potentially use cryptocurrencies for nefarious purposes. Without physical money or a central authority, cryptocurrencies had to find a way to ensure that transactions were secure and that their tokens could not be spent more than once. Bitcoin was born in 2008 when a mysterious person (or persons) named Satoshi Nakamoto (whose true identity remains unknown), found a solution to these issues. Nakamoto’s answer was a digital ledger system with trust in the system achieved through mathematics and cryptography, and with transactions recorded in blockchain. Blockchain is a transparent database that is shared across a network with all transactions recorded in blocks linked together. Nodes—powerful computers connected to the other computers in the network—run the Bitcoin software and validate transactions and blocks. Each node has a copy of the entire blockchain with a history of every transaction that has been executed on it. Nakamoto capped the number of bitcoins that could be created at 21 million. While there is speculation about the math theories that led to the choice of that number, no one really knows the reason behind it. As of this month, an estimated 18.8 million bitcoins were in circulation; it’s expected that all remaining bitcoins will be released by 2140. How do bitcoins enter circulation? New bitcoins are released through mining, which is actually the process of validating and recording new transactions in the blockchain. The miner who achieves this first is rewarded with new bitcoin. Bitcoin mining farm. Photo: Marko Ahtisaari Miners must verify the validity of a number of bitcoin transactions which are bundled into a block. This involves checking 20-30 different variables, such as address, name, timestamp, making sure senders have enough value in their accounts and that they have not already spent it, etc. Miners then compete to be the first to have their validation accepted by solving a puzzle of sorts. The puzzle involves coming up with a number—called the nonce, for ‘number used once’—that when combined with the data in the block and run through a specific algorithm generates a random 64-digit string of numbers and letters. This random number must be less than or equal to the 64-digit target set by the system, known as the target hash. Once the nonce is found that generates the target hash, the winning miner’s new block is linked to the previous block so that all blocks are chained together. This makes the network tamper-proof because changing one block would change all subsequent blocks. The result is broadcast to the rest of the blockchain network and all nodes then update their copies of the blockchain. This validation process, or consensus mechanism, is known as proof of work.The winning miner receives newly minted bitcoin as well as transaction fees paid by the sender. The higher the price of bitcoin, the more miners are competing, and the harder the puzzles get. The Bitcoin protocol aims to have blocks of transactions mined every ten minutes, so if there are more miners on the network with more computing power, the probability of finding the nonce in less than ten minutes increases. The system then makes the target hash more difficult to find by adding more zeroes to the front of it; the more zeros at the front of the target hash, the lower that number is, and the harder it is to generate a random number below it. If there is less computing power operating, the system makes the puzzle easier by removing zeroes. The Bitcoin network adjusts the difficulty of mining about every two weeks to keep block production to ten minutes. Every 210,000 blocks, the bitcoin reward for miners is halved. According to Investopedia, when bitcoin was first mined in 2009, mining one block would earn 50 bitcoins. By November of 2020, the reward was 6.25 bitcoins, but the price was about $17,900 per bitcoin, so a miner would earn $111,875 (6.25 x 17,900) for completing a block. It’s estimated that there are one million bitcoin miners operating and competing, though it’s impossible to be sure because miners with less computing power of their own can join mining pools, which need not report how many active miners they have. “I have a suspicion that Nakamoto had the notion that everyone could be a miner—that you could mine with nothing more than your laptop,” said Farrokhnia. “But as Bitcoin became more popular and more people got on the system and the rewards were actually worth money, you began to see the advent of these mining pools which significantly increased the difficulty level. This turned into a vicious cycle—an arms race—to have the most powerful computers, but then the more powerful hardware miners have, the more difficult it is to find the nonce.” This intense competition is where the environmental impacts of Bitcoin come in. Bitcoin’s environmental impacts Energy consumption and greenhouse gas emissions The process of trying to come up with the right nonce that will generate the target hash is basically trial and error—in the manner of a thief trying random passwords to hack yours—and can take trillions of tries. With hundreds of thousands or more computers churning out guesses, Bitcoin is thought to consume 707 kwH per transaction. In addition, the computers consume additional energy because they generate heat and need to be kept cool. And while it’s impossible to know exactly how much electricity Bitcoin uses because different computers and cooling systems have varying levels of energy efficiency, a University of Cambridge analysis estimated that bitcoin mining consumes 121.36 terawatt hours a year. This is more than all of Argentina consumes, or more than the consumption of Google, Apple, Facebook and Microsoft combined.