When emissions causing global warming are measured, they are done as carbon dioxide equivalent or CO2 equivalent, abbreviated as CO2-eq. A Carbon dioxide equivalent (CO2-eq) is the number of metric tons of CO2 emissions with the same GWP as one metric ton of another GHG.
Based on the Carbon dioxide equivalent rationale, decarbonization is thus broadly defined to cover the reduction of methane (CH4) and nitrous oxide (N2O) emissions, which represent 22% of global GHGs and 82% of total agriculture GHG emissions.
Livestock farming, which produces methane, and the use of nitrogen fertilizer, which produces nitrous oxide, represent the majority of agricultural GHG emissions.
CO2, by definition, has a GWP of 1 because it is the gas used as the reference. Methane (CH4) has a GWP of 28, because methane absorbs much more heat than CO2. Nitrous Oxide (N2O) has a GWP of 265 times that of CO2.
This means that CH4 and N2O are more potent than CO2 even though they represent only a quarter of all gas emissions worldwide (CO2 represents the remaining percentage at 76%).
While much of the public focus has been on CO2 mitigation, addressing agriculture-driven CH4 and N2O emissions is critical to mitigating climate change.
Therefore, decarbonizing the food system extends beyond carbon reduction in crop farming and soil management or farm machinery, to include reduction of carbon emission from livestock farming, and reduction of nitrous oxide and methane emissions from livestock production and manure management.