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

Abstract

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 (95 %; CI range: 11–22) billion metric tonnes (Gt CO2 eq. yr−1), corresponding to 31 % (range: 19 %–43 %) 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 7.2 Gt CO2 eq. yr−1; emissions from land use change, due to deforestation and peatland degradation, were 3.5 Gt CO2 eq. yr−1; and emissions from pre- and post-production processes – manufacturing of fertilizers, food processing, packaging, transport, retail, household consumption and food waste disposal – were 5.8 Gt CO2 eq. yr−1. Over the study period 1990–2019, agri-food system emissions increased in total by 17 %, 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 25 %, while emissions within the farm gate increased 9 %. In 2019, in terms of individual greenhouse gases (GHGs), pre- and post-production processes emitted the most CO2 (3.9 Gt CO2 yr−1), preceding land use change (3.3 Gt CO2 yr−1) and farm gate (1.2 Gt CO2 yr−1) emissions. Conversely, farm gate activities were by far the major emitter of methane (140 Mt CH4 yr−1) and of nitrous oxide (7.8 Mt N2O yr−1). Pre- and post-production processes were also significant emitters of methane (49 Mt CH4 yr−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 (2.2 Gt CO2 eq. yr−1). They also more than doubled in non-Annex I parties (to 3.5 Gt CO2 eq. yr−1), becoming larger than emissions from land use change. By 2019 food supply chains had become the largest agri-food system component in China (1100 Mt CO2 eq. yr−1), the USA (700 Mt CO2 eq. yr−1) and the EU-27 (600 Mt CO2 eq. yr−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 https://doi.org/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.

Roadmap for achieving net-zero emissions in global food systems by 2050

“…1 ). This estimate is consistent with the emissions range of recent estimates covering the same period (9–22 GtCO 2 e/y) 3 , 6 , 16 , 18 , 20 – 22 . Four value-chains–beef, milk, rice and maize–are responsible for nearly 65% (13.9 GtCO 2 e) of total FS emissions, and seven value-chains (+ wheat, pig and poultry) are responsible for almost 80% of emissions (17.2 GtCO 2 e).…”

“…1 ). Close to 70% of FS emissions come from land-use change and farming activities 6 , 16 .

Figure 1 Global food systems emissions in 2020 ( A ) and estimated global food systems emissions 2010–2050 ( B ).

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“…Although the impressive commitment to the net-zero agenda of countries and the world’s biggest food companies, guidance offering multiple options for achieving net-zero emissions in global FSs and informing the effectiveness of pledges and catalyze meaningful climate action is still needed. To date, most studies have focused on estimating global food systems emissions 6 , 18 and evaluating potential mitigation through a few and aggregated pathways using complex models 3 , 10 and none has proposed a roadmap towards net-zero food systems, which has lately been highly demanded by several food systems actors 19 .…”

Greenhouse gas emissions from municipal wastewater treatment facilities in China from 2006 to 2019

“…Therefore, GHG emission factors of a biological technology obtained from references are not representative for real emission factors of all WWTPs with the same technology. (3) GHG emissions from industrial WWTPs are not available and thus not included in our study although being important GHG emission sources of wastewater treatment systems [52][53][54] . For instance, Xing et al reported that CH 4 emissions from on-site industrial wastewater treatment were always higher than that of domestic wastewater treatment between 2003 and 2008 in China.…”

Climate change and the urgency to transform food systems

“…That said, post farm emissions (e.g. from energy use in food processing, food transport, food storage, cooking) have been rising substantially in recent years, requiring a rethink of mitigation strategies for the food sector (11). A look across the whole food system therefore becomes important for finding the biggest levers of change.…”