New methods have been proposed for calculating CO2 equivalents for short-lived climate gases such as methane. These take into account the fact that the warming effect of such gases depends on previous changes in emissions, rather than on their total atmospheric concentration, as it is the case for carbon dioxide. For methane from rumination, it should also be taken into account that there is a constant recycling of carbon emitted in the form of methane through agricultural forage production. In contrast to methane from fossil sources, an equilibrium between emission and degradation of methane can thus be established, without a further warming effect. As a conclusion, the prioritization of measures to reduce fossil methane emissions should be even stronger than already indicated for cost reasons. Furthermore, it becomes clear that in an equilibrium situation a CO2 pricing of methane from rumen digestion does not make sense from a climate policy point of view.
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