Greenhouse gas (GHG) emissions associated with different products or activities are typically reported as a total ‘carbon footprint’, combining separate gases into a ‘carbon dioxide equivalent’ (CO2e) quantity. As GHGs differ significantly in both their atmospheric lifespans and warming impacts, however, attempting to describe emissions using a single combined currency can lose important information. This concern is especially notable for methane, as its short atmospheric lifespan results in a large range in CO2 equivalent valuations depending on the timescale of interest and climate metric used. Activities emitting a large amount of methane, such as beef production, are consequently also highly sensitive to these dynamics.
This paper reviewed the recent scientific literature to determine the availability of separate GHG emissions from studies of beef production systems. It was only possible to obtain disaggregated emissions data from 29% of otherwise complete beef carbon footprints. The paper demonstrates that without knowing the emissions of separate gases, it is impossible to test alternative time-frames or alternative metrics, to standardise footprints over time as atmospheric science progresses, or to test agricultural emissions in climate modelling approaches. This may have significant implications for how agricultural emissions are communicated in relation to other GHG-emitting activities, or the emissions efficiency of different types of production (for example, whether cattle fed predominantly grass-based diets are more or less efficient than those with high-energy feeds). The paper calls on researchers to publish separate emissions data to enable more detailed assessment of the climate impacts of agricultural production.