Agriculture's Contribution to Climate Change and Role in Mitigation Is Distinct From Predominantly Fossil CO2-Emitting Sectors

Agriculture, and particularly livestock production, contributes to climate change primarily through emissions of the potent greenhouse gases methane and nitrous oxide. But while a portion of all fossil carbon dioxide emissions (the primary contributor to global warming) will stay in the atmosphere for millennia, methane and nitrous oxide have much shorter atmospheric lifespans: from decades to centuries, respectively. This results in different behaviours for the different gases, and means that while ‘net-zero’ emissions of CO2 are essential to stop continued warming, some ongoing methane and even nitrous oxide emissions may be compatible with stable temperatures. In this paper we illustrate these points and discuss some of the consequences. In light of these differences we recommend more precise language for reporting greenhouse gas emissions to move beyond ‘carbon[-equivalents]’ and specify the gases being discussed; this is particularly important for researchers publishing emission data. While the food system must change to meet our climate targets, these dynamics mean there is still scope to negotiate the ‘sustainable’ space for some level of agricultural emissions, and we argue that a wider appreciation of the differences between gases can contribute to wider discussions about how to successfully mitigate climate change.