Pre- and post-production processes increasingly dominate greenhouse gas emissions from agri-food systems

[摘要] We present results from the FAOSTAT emissions shares database, covering emissionsfrom agri-food systems and their shares to total anthropogenic emissions for196 countries and 40 territories for the period 1990–2019. We find that in2019, global agri-food system emissions were 16.5 (95 %; CI range: 11–22)billion metric tonnes (Gt CO 2  eq. yr −1 ), corresponding to 31 %(range: 19 %–43 %) of total anthropogenic emissions. Of the agri-foodsystem total, global emissions within the farm gate – from crop andlivestock production processes including on-farm energy use – were 7.2 Gt CO 2  eq. yr −1 ; emissions from land use change, due to deforestationand peatland degradation, were 3.5 Gt CO 2  eq. yr −1 ; and emissionsfrom pre- and post-production processes – manufacturing of fertilizers,food processing, packaging, transport, retail, household consumption andfood waste disposal – were 5.8 Gt CO 2  eq. yr −1 . Over the studyperiod 1990–2019, agri-food system emissions increased in total by 17 %,largely driven by a doubling of emissions from pre- and post-productionprocesses. Conversely, the FAOSTAT data show that since 1990 land useemissions decreased by 25 %, while emissions within the farm gateincreased 9 %. In 2019, in terms of individual greenhouse gases (GHGs),pre- and post-production processes emitted the most CO 2 (3.9 Gt CO 2  yr −1 ), preceding land use change (3.3 Gt CO 2  yr −1 )and farm gate (1.2 Gt CO 2  yr −1 ) emissions. Conversely, farm gateactivities were by far the major emitter of methane (140 Mt CH 4  yr −1 ) and of nitrous oxide (7.8 Mt N 2 O yr −1 ). Pre- andpost-production processes were also significant emitters of methane (49 Mt CH 4  yr −1 ), mostly generated from the decay of solid food waste inlandfills and open dumps. One key trend over the 30-year period since 1990highlighted by our analysis is the increasingly important role offood-related emissions generated outside of agricultural land, in pre- andpost-production processes along the agri-food system, at global, regionaland national scales. In fact, our data show that by 2019, pre- andpost-production processes had overtaken farm gate processes to become thelargest GHG component of agri-food system emissions in Annex I parties (2.2 Gt CO 2  eq. yr −1 ). They also more than doubled in non-Annex I parties(to 3.5 Gt CO 2  eq. yr −1 ), becoming larger than emissions fromland use change. By 2019 food supply chains had become the largest agri-foodsystem component in China (1100 Mt CO 2  eq. yr −1 ), the USA (700 Mt CO 2  eq. yr −1 ) and the EU-27 (600 Mt CO 2  eq. yr −1 ). This has important repercussions for food-relevant national mitigation strategies,considering that until recently these have focused mainly on reductions ofnon-CO 2 gases within the farm gate and on CO 2 mitigation from landuse change. The information used in this work is available as open data withDOI https://doi.org/10.5281/zenodo.5615082 (Tubiello et al., 2021d). It is also available tousers via the FAOSTAT database ( https://www.fao.org/faostat/en/#data/EM ; FAO, 2021a), with annual updates.

[学科分类] 眼科学