Temporary carbon dioxide removals to offset methane emissions

Abstract: Unlike CO2, methane emissions have a particularly large short-term effect on temperature. This paper argues that the largely temporary temperature effects of methane emissions are well suited to being offset by temporary CO2 removal. Temporally matching the offsetting temperature reductions to methane’s temperature impulse eliminates the sizeable intertemporal welfare transfers that occur when methane is offset by equivalent permanent CO2 removals. Assessing equivalence on the basis of avoided economic damages suggests that about 87 tonnes of temporary CO2 removal over a period of 30 years are needed to offset one tonne of methane. Agreement on the appropriate quantity of temporary offsets is insensitive to controversial parameters such as the social discount rate, climate damages and future emission scenarios. Short-term monitoring periods of 20–30 years are also likely to be more credibly enforceable for various nature-based CO2 removal projects than long-term monitoring requirements.