A new report from the Cambridge Centre for Alternative Finance (CCAF) has confirmed that Ethereum's transition to proof-of-stake (PoS) slashed its annual carbon emissions by approximately 99.98%. The study, conducted in collaboration with the Crypto Carbon Ratings Institute (CCRI), provides the first comprehensive post-Merge measurement of the network's environmental footprint.
Emissions and power demand collapse
According to the report, Ethereum's annual CO₂-equivalent emissions dropped from about 10.3 megatonnes before the Merge on September 15, 2022, to roughly 2.37 kilotonnes afterward. Total network power demand fell from approximately 2.4 gigawatts (GW) to just 0.90 megawatts (MW), with annual electricity consumption declining to around 7.87 gigawatt-hours (GWh).
Real-world measurements across 20 client types
To estimate energy use, researchers used wall-plug measurements for 20 different node software combinations spanning execution and consensus layers. A typical home mini-PC consumed a median of 18 watts, while a data-center-grade workstation used about 153 watts. After factoring in node distribution, the average power draw per node was calculated at 105 watts. Based on node counts from MigaLabs, the report estimated approximately 8,522 active nodes as of May 2026.
Geographic concentration and carbon intensity
Node locations are heavily concentrated: the United States hosts 31% of nodes, Germany 16%, Finland 8%, and France 6%, with the top four countries accounting for 62% of all nodes. Cloud providers Hetzner, AWS, and OVH together run about 40% of nodes, raising concerns about single points of failure. The report also analyzed the carbon intensity of electricity grids in node-hosting countries, finding that roughly 56.4% of power came from sustainable sources (renewables plus nuclear) and 43.6% from fossil fuels. It warned that if all nodes ran on hydropower versus coal, annual emissions would differ by a factor of 47, meaning future reductions depend more on grid decarbonization than hardware efficiency.
Validators vs. physical nodes
The report cautioned against conflating validators with physical nodes. After the Pectra upgrade in May 2025, active validators rose to about 894,000, but the number of power-consuming physical nodes remained around 8,522. The report emphasized that energy consumption scales with nodes, not validators.
Future outlook and ongoing monitoring
Looking ahead, the report discussed stateless verification, which could reduce node hardware requirements to smartphone-level performance. However, it noted that the "provers" generating cryptographic proofs might be high-powered machines, making the net energy impact uncertain. With major upgrades like Dencun and Pectra continuously reshaping the network, the CCAF stressed the need for ongoing reassessment. Updated estimates are available via the Cambridge Blockchain Network Sustainability Index (CBNSI) dashboard.