The Asian Development Bank estimates that expanding Baku Metro passenger capacity could reduce carbon emissions by 70,000 tons per year. Each additional metro rider prevents roughly 700 grams of CO2, based on monitoring from the Delhi Metro and Azerbaijan's grid emission factor. The ADB says an extra 100 million passengers would hit that 70,000 ton figure. The report notes the Baku Metro could qualify as a carbon market project under UNFCCC methodology for mass public transport. But the ADB warns that preparing and monitoring such projects is complex, and annual reductions need to be at least 50,000 tons of CO2 to be economically viable. The current network carried 222 million passengers in 2017 across 37 kilometers of track.
