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

Abstract

We present results from the FAOSTAT emissions shares database, covering emissions from agri-food systems and their shares to total anthropogenic emissions for 196 countries and 40 territories for the period 1990-2019. We find that in 2019, global agri-food system emissions were 16.5 (95g%; CI range: 11-22) billion metric tonnes (GtgCO2geq.gyr-1), corresponding to 31g% (range: 19g%-43g%) of total anthropogenic emissions. Of the agri-food system total, global emissions within the farm gate - from crop and livestock production processes including on-farm energy use - were 7.2gGtgCO2geq.gyr-1; emissions from land use change, due to deforestation and peatland degradation, were 3.5gGtgCO2geq.gyr-1; and emissions from pre- and post-production processes - manufacturing of fertilizers, food processing, packaging, transport, retail, household consumption and food waste disposal - were 5.8gGtgCO2geq.gyr-1. Over the study period 1990-2019, agri-food system emissions increased in total by 17g%, largely driven by a doubling of emissions from pre- and post-production processes. Conversely, the FAOSTAT data show that since 1990 land use emissions decreased by 25g%, while emissions within the farm gate increased 9g%. In 2019, in terms of individual greenhouse gases (GHGs), pre- and post-production processes emitted the most CO2 (3.9gGtgCO2gyr-1), preceding land use change (3.3gGtgCO2gyr-1) and farm gate (1.2gGtgCO2gyr-1) emissions. Conversely, farm gate activities were by far the major emitter of methane (140gMtgCH4gyr-1) and of nitrous oxide (7.8gMtgN2Ogyr-1). Pre- and post-production processes were also significant emitters of methane (49gMtgCH4gyr-1), mostly generated from the decay of solid food waste in landfills and open dumps. One key trend over the 30-year period since 1990 highlighted by our analysis is the increasingly important role of food-related emissions generated outside of agricultural land, in pre- and post-production processes along the agri-food system, at global, regional and national scales. In fact, our data show that by 2019, pre- and post-production processes had overtaken farm gate processes to become the largest GHG component of agri-food system emissions in Annex I parties (2.2gGtgCO2geq.gyr-1). They also more than doubled in non-Annex I parties (to 3.5gGtgCO2geq.gyr-1), becoming larger than emissions from land use change. By 2019 food supply chains had become the largest agri-food system component in China (1100gMtgCO2geq.gyr-1), the USA (700gMtgCO2geq.gyr-1) and the EU-27 (600gMtgCO2geq.gyr-1). This has important repercussions for food-relevant national mitigation strategies, considering that until recently these have focused mainly on reductions of non-CO2 gases within the farm gate and on CO2 mitigation from land use change. The information used in this work is available as open data with DOI 10.5281/zenodo.5615082 (Tubiello et al., 2021d). It is also available to users via the FAOSTAT database (https://www.fao.org/faostat/en/#data/EM; FAO, 2021a), with annual updates.