Carbon neutrality assumption hides significant contribution of growers to carbon sequestration

Current greenhouse gas accounting systems explicitly exclude carbon changes in annual crop biomass. However, neglecting the sequestration and emission of biogenic carbon from annual crops can hide a part of the carbon responsibilities of growers and food consumers, hindering the attainment of social equity. Here, we defined a new system boundary that encompassed crop carbon sequestration, straw consumption, and human metabolism and analyzed the magnitude, structure, and spatiotemporal variation of carbon emissions and carbon sinks in the crop production-consumption system of Chinese growers from 1995 to 2018. We found that the net carbon sink for growers in 2018 was -463 Mt CO2e when accounting for crop production emissions and soil carbon sequestration using the old boundary, while under the new boundary it was 1042 Mt CO2e. Therefore, it is desirable to strengthen research on the distribution of carbon responsibilities among different groups and regions in the future.