The hydrogen is cracked off and the CO2 is vented. Plus every kg of extracted methane is accompanied a few hundred grams of fugitive methane which is equivalent

The hydrogen is cracked off and the CO2 is vented. Plus every kg of extracted methane is accompanied a few hundred grams of fugitive methane which is equivalent to another 1-2 kg of CO2. Luckily electrolysis will soon be cheaper in parts of the world (or everywhere if we priced in externalities).