Pre- and post-production processes increasingly dominate greenhouse gas emissions from agri-food systems
Authors: Tubiello Francesco N. , Karl Kevin , Flammini Alessandro , Gütschow Johannes , Obli-Laryea​​​​​​​ Griffiths , Conchedda Giulia , Pan Xueyao , Qi Sally Yue , Halldórudóttir Heiðarsdóttir Hörn , Wanner Nathan , Quadrelli Roberta , Rocha Souza Leonardo , Benoit Philippe , Hayek Matthew , Sandalow David , Mencos Contreras​​​​​​​ Erik , Rosenzweig Cynthia , Rosero Moncayo Jose , Conforti Piero , Torero Maximo 
Published: April 2022

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.