The carbon footprint of Bitcoin — and why Ethereum is now different
Bitcoin’s network consumes roughly 120–150 terawatt-hours of electricity a year — comparable to a mid-size country like Argentina or Norway, according to the Cambridge Bitcoin Electricity Consumption Index. Its carbon footprint depends on where the mining happens, but it’s genuinely large. The headline, though, hides two things worth getting right.
”Per transaction” is the wrong number
You’ll see scary figures like “one Bitcoin transaction = X hundred kg of CO₂.” Treat them with caution. Bitcoin’s energy use is driven by mining (securing the network), not by the number of transactions — miners burn roughly the same power whether the network processes one transaction or thousands. Dividing total energy by transaction count produces a number that swings wildly and doesn’t reflect how the system actually works. The honest framing is network-level: a large, country-scale electricity draw.
Not all crypto is the same any more
This is the big update most coverage misses. In September 2022, Ethereum switched from proof-of-work to proof-of-stake (“The Merge”) and cut its energy use by about 99.9% overnight. Proof-of-stake chains — now most major ones except Bitcoin — have a tiny energy footprint. So “crypto is an environmental disaster” is increasingly a statement about Bitcoin specifically, not the whole field.
| Network | Relative energy use |
|---|---|
| Bitcoin (proof-of-work) | Country-scale (~120–150 TWh/yr) |
| Ethereum (post-2022, proof-of-stake) | ~99.9% lower than before |
| Most other proof-of-stake chains | Negligible |
The honest framing
Bitcoin’s footprint is real and large, and where it’s mined (coal vs. hydro vs. flared gas) changes the carbon a lot. But the careful version avoids two traps: misleading per-transaction math, and lumping all crypto together when the second-biggest network already fixed its energy problem. As with the rest of your digital footprint, the systemic question — what powers the computation — matters more than any single click or transaction.
Sources: Cambridge Centre for Alternative Finance, Bitcoin Electricity Consumption Index; Ethereum Foundation on the energy impact of The Merge (2022); analyses cautioning against per-transaction energy figures.