Conference Agenda

Methane (CH$_4$) is between 30 and 100 times more powerful a Green-house Gas than Carbon Dioxide (CO$_2$). The time profile of higher temperatures caused by CH$_4$ is concentrated in the first 20 years after the initial impulse compared to the lower, more permanent effects of CO$_2$ emissions. We argue that these largely temporary temperature effects of CH$_4$ emissions are apt to be offset by temporary CO$_2$ removals, administered by temporary contracts. Short term, say 20-year, contracts are more credibly monitored and enforced than the eternal contracts for permanent removals. Further, the temporal matching of offsetting temperature reductions to the temperature impulse of CH$_4$ removes the major intertemporal transfers that arise when CH$_4$ is offset by equivalent permanent solutions. Agreement on the appropriate quantity of temporary carbon offsets is therefore insensitive to controversial parameters such as the social discount rate, climate damages and emissions scenarios. Assigning temporary carbon removal projects to offset methane emissions therefore leverages projects viewed as low quality to nullify short-lived climate damages. Separate markets could be organized around offsetting CH$_4$ emissions in the agricultural sector, where difficult-to-remove ‘residual’ emissions abound. Credits in this market for CH$_4$ offsets could be based on metrics of equivalence between CH$_4$ and CO$_2$ over an agreed horizon. Using the equivalence based on avoided economic damages suggests that, for 20 year contracts, 136 temporary CO$_2$ removals are needed to offset 1-tonne of CH$_4$. This level of equivalence therefore provides strong incentives for reducing emissions for all but the most expensive cases, rather then offsetting them using temporary projects.