Ethereum celebrated 2020 the only way a blockchain knows how — with a network upgrade.
The Muir Glacier network upgrade (hard fork) was activated at block number 9,200,000 on Jan 2, 2020, with one Ethereum Improvement Proposal (EIP). EIP 2384 effectively delays the difficulty bomb for another 4,000,000 blocks (~611 days).
While other network upgrades and subsequent changes to the difficulty bomb have been accompanied by a change of ether issuance, there was no reduction in the Muir Glacier upgrade so the issuance will remain at 2 ETH per block.
What is the Ethereum difficulty bomb/ice age?
The difficulty bomb, sometimes lightheartedly referred to as the “ice age” is an algorithm designed to increase the difficulty to mine Ethereum blocks over time.
The history of the difficulty bomb and why it exists
A couple of ideas underlie the difficulty bomb/ice age concept which originates from the initial design of Ethereum. For better or worse, Ethereum has often operated under the ethos of “continuous innovation” requiring frequent upgrades to the Ethereum blockchain. Network upgrades are costly for the network as they require every node on the network to upgrade to the latest version of the protocol. If these nodes do not upgrade, they will be forked off the network. The coordination costs associated with upgrades have historically meant that blockchain projects avoided them.
So the difficulty bomb was, in part, encoded in to force regular hard forks as a way to normalize the idea of upgrading the network. This naturally has also provided opportunities to make other protocol upgrades. Typically, the difficulty bomb has been reset in conjunction with making other protocol changes, so it has arguably worked quite well up to now.