But each CO₂ produced by burning a hydrocarbon also means 2 H₂O (or 4 H₂O for methane), so that accounts for another 65 ppm (or more). Only ~40% of the CO₂ pro

But each CO₂ produced by burning a hydrocarbon also means 2 H₂O (or 4 H₂O for methane), so that accounts for another 65 ppm (or more). Only ~40% of the CO₂ produced since 1850 has stayed in the atmosphere. 130 ppm / 0.4 = 325 ppm. That's half the missing oxygen right there.