The Merge (Ethereum)

The Merge was the upgrade that switched Ethereum from proof of work to proof of stake. It took place on 15 September 2022, when Ethereum's original execution chain was joined with the Beacon Chain, a proof-of-stake chain that had been running in parallel since December 2020.

After the Merge, miners and their GPUs were no longer needed. Blocks are now proposed and attested by validators who stake 32 ETH each, and new blocks come in fixed 12-second slots. The Ethereum Foundation estimated the change cut Ethereum's energy consumption by about 99.95%. Daily ETH issuance also fell sharply, by roughly 90%, because validators need far less reward than miners did.

Contrary to a common belief, the Merge did not lower gas fees or make Ethereum much faster; scaling was left to layer-2 rollups. Staked ETH could not be withdrawn until the later Shapella upgrade in April 2023.