Sell Bitcoin. Save Lives.

Explicitly selling your Bitcoin literally saves lives. Check out these simulators.

Carbon emissions are calculated to lead to one premature death for every 300 to 3,000 tonnes of CO2 emitted [*], and are projected to make an area containing 3 billion people uninhabitable [*].

Bitcoin is currently estimated to be responsible for 65.4 megatonnes of CO2 every year [*] with some estimates as high as 114 megatonnes [*].

So, just doing the math here, Bitcoin is adding between 21,800 and 380,000 premature deaths annually, and contributing significantly to climate change that will displace billions.

We can stop this! But to do so you need to explicitly sell Bitcoin.

What? I thought it was Bitcoin transactions that were the problem.

Nope, you need to sell Bitcoin. Sitting on it is not enough.

When people talk about the carbon cost of a Bitcoin "transaction", that's an amortized cost. They're adding up the carbon intensity of Bitcoin overall and then dividing by the number of transactions. But the carbon cost of Bitcoin has nothing to do with the amount of transactions. Instead, it is dependent on the amount of power spent on mining blocks, which are mined roughly once every 10 minutes, independent of how full the blocks are. As we'll show on this page, carbon intensity and thus deaths are linearly related to Bitcoin price. The only move here is to put as much downward pressure on Bitcoin price as possible.

This situation is true of all Proof of Work cryptocurrencies, like Bitcoin. Other cryptocurrencies that use consensus algorithms like Proof of Stake do not have this problem. If you like cryptocurrency, that's great! You can still use cryptocurrency without killing people! Green cryptocurrency is here, today, with more coming soon [*]! But first, sell your Bitcoin. Don't buy more.

Don't believe me? Here's the first simulator. Hit the start button. Try sliding the simulation step time to be large, then watch as the annual deaths asymptote directly matches your price changes.

We're going to walk through how this simulator is made together. Before we do though, maybe you don't know what Bitcoin is or something. Let's level set.

Let's level set - a birds' eye view of how Bitcoin mining works.

Skip this section if you've heard this before.

Bitcoin is a globally shared digital ledger that can keep track of amounts in an unforgeable way. If Alice wants to transfer 5 bitcoin to Bob, she will enter a transfer of "5 bitcoin" to Bob into the global ledger. Her balance will decrease by 5 and his will increase by 5. There is no such thing as a "bitcoin" on its own apart from transfers on this ledger. Naturally, two questions arise - where do initial bitcoin amounts come from, and how is this ledger protected from invalid transactions?

In Proof of Work cryptocurrencies (of which Bitcoin is the first), both questions are resolved by a lottery system called mining. Anyone running a computer can enter the lottery. A valid lottery ticket is one that has a set of some valid transactions, refers to the previous valid lottery ticket, and solves a cryptographic puzzle successfully. If a computer finds (or mines) the next block of transactions successfully according to the above rules, the rules then specify that its operator is awarded some brand new, just minted bitcoin. This is the agreed upon behavior by all Bitcoin software, and if one of these lottery tickets doesn't play by the rules all of the other Bitcoin software plays by, the lottery ticket will be ignored. As you might imagine, the best strategy for maximizing Bitcoin mining rewards is to obtain the most valid lottery tickets.

The costliest step in creating a lottery ticket is the cryptographic puzzle, (this is called the Proof of Work) and the rate at which these can be attempted is called the hash rate. Dedicated Bitcoin mining computers are rated in terms of terahashes per second, or how many trillion cryptographic puzzles can be attempted every second.

Because the system would fall apart if lottery tickets were being distributed trillions of times a second, the participants of the Bitcoin network all agree on a system that adjusts the expected number of attempts to find a valid lottery ticket (the difficulty) such that the network on average only has one successful lottery ticket every 10 minutes. No matter how many lottery participants there are, there will only be one winner every 10 minutes.

This is standard lottery probability - the value of a lottery ticket is equal to the probability of the lottery ticket winning times the reward if it wins minus the cost of obtaining it. The monetary value provided by one exahash (one billion billion lottery attempts) is equal to the percent of the total network one exahash represents times the block reward minus the cost of performing one exahash worth of attempts. As an aside, the Bitcoin network is currently performing around 200 exahashes per second, so 1 exahash per second gives you 0.5% chance of winning the lottery.

As a result, chances of winning the lottery, in expectation, are exactly equal to the percent of the total network hash rate you control. Miners are incentivized to maximize the percent of the network hashrate they control, as long as it is economically feasible to do so.

A note about asset classes in case you don't know: there are other cryptocurrencies besides Bitcoin! Bitcoin is not the only cryptocurrency! It's only Proof of Work cryptocurrencies that the above applies to. Many other cryptocurrencies use alternate consensus mechanisms, such as Algorand, Avalanche, Cardano, Cosmos, Polkadot, Polygon, Solana, Tezos, etc., and soon Ethereum, and these are not nearly as bad as Proof of Work. If you're interested in investing in cryptocurrency, you'll be delighted to know that the whole market moves together with high correlation (so far), and so you should feel just dandy about selling all of your Proof of Work cryptocurrency and trading it for something else.

Okay, let's simulate a single Bitcoin miner

Below, we're going to calculate what you can expect to earn by running mining computers (your profit) given your energy costs.

How does this work? Well first off, if you're on mobile, it might not, lol. The simulator probably looks better on desktop. I haven't been a web developer in 15 years. Can you imagine how much has changed in 15 years of web development? I'm still shocked KHTML beat Trident and Gecko. I tried to make this responsive, but maybe go get your computer.

Okay, but so how does this work? This simulator simulates on regular intervals (the Sim step size). With default settings, each data point is one week of simulated time. For each simulator step:

  1. The simulator calculates the energy cost to you of your configured hashrate, given your miner efficiency and the cost of energy. It then graphs cumulative cost. Note that for large hashrates, this is the same as running multiple mining computers. Your mining operation may have lots and lots of hardware!
  2. It calculates your expected revenue; this is your "expected earnings" (before costs) in a mathematical sense. Your actual earnings are random and based on who wins the lottery, but in expectation over long periods of time, your actual earnings will match the expected earnings, so this is fine. It multiplies the simulator step's block rewards by your chances of winning the Bitcoin mining lottery. This is also graphed cumulatively.
  3. It subtracts your costs from your earnings, and that's your profit. If your profit is going up, great! If your profit is going down, you're losing money!

For this first simulator, we're going to assume you already have all the mining computers you could possibly want lying around and freely obtainable. No capital expenditure yet! Otherwise, the numbers are pulled from real life right now (as I'm writing): the Bitcoin network is around 200 EH/s when I looked, I looked up electricity prices, and so on.

Go ahead and play around with it - it's worth getting a feel for how quickly mining can turn from a good thing to a bad thing. In particular, check out how poorly GPUs and CPUs do (the nVidia and Intel presets).

The next obvious thing. What happens when miners make decisions based on profits?

So, as a miner, let's say you're making profits (or losses!) and want to make decisions based on that. In particular, if you have a healthy margin of profit, perhaps you'd like to reinvest some percent beyond a minimum profit into acquiring more mining hardware, so you can make more profit! Alternatively, if you lose money, perhaps you'd like to shut down and sell some mining hardware so you lose less money.

This is kind of like that Paperclips game [*], except that has a better game interface than this simulator. Sorry. Here are some fun puzzles to solve:

  • What is the highest cumulative profit you can get to in 10 years of simulator time by only adjusting the minimum profit and reinvestment percent from default values? Hint: you may need to have a different reinvestment strategy at different points of time.
  • What happens to the hashrate if the price of Bitcoin falls?
  • What happens to profits in the long term if your minimum profit percent is zero?
  • At what hashrate does increasing your hashrate stop being a good strategy?

Hopefully you can see the (perhaps intuitive) outcome demonstrated that reinvestment provides the opportunity to get to much higher profits.

The last puzzle is especially pertinent. Once you find the answer you'll notice that, for this simulator, it's much more than the default "Other miners" value, which means your miner would own the majority of the network.

Of course, this simulator is missing a huge component; other people! The Bitcoin price will change and the other miners will also respond to incentives.

Multiple participants

Okay, let's simulate some Bitcoin price changes (the annual price change % field) and replace that Other miners value with actual simulated miners.

Some more puzzles for you to figure out:

  • What happens to the overall hashrate as the Bitcoin price changes now?
  • If one miner is more efficient than other miners, do the other miners drop out of the network? Does the same thing happen when the annual price change % of Bitcoin is greater than zero?
  • What happens when one miner is willing to have a lower minimum profit than others?

Puzzle spoilers!

  • Just like the very first simulator at the beginning, if you increase the simulator step size to be large, the miner pool hash rates hit an asymptote and stop growing. Once that happens, Bitcoin price linearly translates to changes in hashpower. If Bitcoin goes up, miners can justify spending more on mining. If Bitcoin goes down, miners turn off mining rigs.
  • If one miner is more efficient than others and the Bitcoin price is steady or going down, the more efficient miner takes over the network and the other miners drop out of the network. But, if Bitcoin price is steadily increasing over time (a positive annual price change %), all of the hashrates continue to go up. So as long as Bitcoin price is going up, coal miners will remain viable, regardless of how much cheaper solar is.
  • Note that miners that are willing to take a lower minimum profit are also able to take over the network, unless other miners also do. This is clearly a race to the bottom in terms of profit margins.

It's worth drilling in on the middle point for a second. A common refrain from Proof of Work fans is that "Bitcoin mining incentivizes green energy!" No, it doesn't. What it incentivizes is cheap energy as long as the price is not going up. If the price is going up (or even if the equilibrium point hasn't been hit yet), as you can see in the simulator, even more expensive or less efficient energy is still profitably sunk into Bitcoin mining.

Okay, I'm sure you know where this is going. Let's do this exact same simulator now but graph carbon output.

The exact same simulator now but graph carbon output

Okay, this is the same simulator as the last simulator, and it is also the same simulator as the one at the beginning! The only difference between the three is what controls and graphs are shown. Surprise!

Try toggling on and off the "advanced" checkbox.

By adjusting just the controls in the "unadvanced" view, you should be able to see that Bitcoin price is directly translated into carbon emitted by miners, and thus lives lost.

It doesn't matter how many transactions are in a Bitcoin block. As long as unrenewable energy exists, the price of Bitcoin itself drives carbon output.

If you care about the people on the planet, you need to do anything you can to put downward pressure on Bitcoin price. Explicitly sell your bitcoin, get your friends to sell theirs, etc.

Even just holding Bitcoin is bystanding an opportunity to prevent human death.