Greenhouse gas emissions from food systems: building the evidence base

Abstract

New estimates of greenhouse gas (GHG) emissions from the food system were developed at the country level, for the period 1990–2018, integrating data from crop and livestock production, on-farm energy use, land use and land use change, domestic food transport and food waste disposal. With these new country-level components in place, and by adding global and regional estimates of energy use in food supply chains, we estimate that total GHG emissions from the food system were about 16 CO2eq yr−1 in 2018, or one-third of the global anthropogenic total. Three quarters of these emissions, 13 Gt CO2eq yr−1, were generated either within the farm gate or in pre- and post-production activities, such as manufacturing, transport, processing, and waste disposal. The remainder was generated through land use change at the conversion boundaries of natural ecosystems to agricultural land. Results further indicate that pre- and post-production emissions were proportionally more important in developed than in developing countries, and that during 1990–2018, land use change emissions decreased while pre- and post-production emissions increased. We also report results on a per capita basis, showing world total food systems per capita emissions decreasing during 1990–2018 from 2.9 to 2.2 t CO2eq cap−1, with per capita emissions in developed countries about twice those in developing countries in 2018. Our findings also highlight that conventional IPCC categories, used by countries to report emissions in the National GHG inventory, systematically underestimate the contribution of the food system to total anthropogenic emissions. We provide a comparative mapping of food system categories and activities in order to better quantify food-related emissions in national reporting and identify mitigation opportunities across the entire food system.

Emissions of greenhouse gases from energy use in agriculture, forestry and fisheries: 1970–2019

“…Emissions from energy use in agriculture are only about onefifth of the total in CO 2 eq generated from crop and livestock production (Tubiello et al, 2021); however, they represent an important contribution in terms of CO 2 gas, with the other process emitting CO 2 on the farm being the drainage of organic soils. They are therefore of great importance to GHG mitigation in agriculture.…”

“…Other uses beyond the farm may include power for forestry ma-chinery and fishing vessels (Dubois et al, 2017). On-farm energy use is a significant component of agricultural production and growth (Sims and Flammini, 2014;Utz, 2011); however, it often attracts less attention in food-related emissions analysis relevant to national determined contributions (Tubiello et al, 2021) as the on-farm energy use emissions are reported instead under the "energy" sector of the national greenhouse gas (GHG) inventories. In fact, countries regularly submit to the UN Framework Convention on Climate Change (UNFCCC), containing only non-CO 2 emissions from crop and livestock biophysical processes, for instance, enteric fermentation in ruminants or nitrous oxide from fertilizers on cropland (IPCC, 2006;Tubiello, 2019).…”

“…Within the UNFCCC context, emissions from agriculture are currently about 5 Gt CO 2 eq yr −1 , having increased by roughly 50 % since 1961 (Tubiello, 2019). They are dominated by livestock processes and are fairly equally split between CH 4 and N 2 O components, in single gas units corresponding to annual emissions in 2019 of 140 Mt CH 4 and 7.7 Mt N 2 O, respectively (FAO, 2021b;Tubiello et al, 2021).…”

Climate Solutions Double as Health Interventions

“…Similarly, the EAT-Lancet Commission found that shifting to a universal healthy reference diet-rich in fruits, vegetables, whole grain, legumes and low in red meat-could help prevent about 11 million deaths per year by 2050 [68]. These dietary shifts would also reduce emissions from ruminant animals such as beef and dairy cattle, which are the primary sources of on-farm greenhouse gas emissions from food production [69]. The health benefits of reduced red meat consumption may be more pronounced in high-income countries where excess meat consumption is common and should not overshadow the fact that livestock provide an essential nutrient source for people in many low-and middle-income countries [70].…”

N2O Emissions from Two Austrian Agricultural Catchments Simulated with an N2O Submodule Developed for the SWAT Model

“…Nitrous oxide (N2O) is a potent greenhouse gas (GHG) that contributes to global warming and mainly stems from agricultural soils [1]. Agricultural activities are responsible for an estimated two-thirds of the total anthropogenic N2O emissions in the world [2].…”