Supply chain joins deforestation and farming practices as main source of emissions in agri-food sector

The food supply chain is on course to overtake farming and land use as the largest contributor to greenhouse gases (GHGs) from the agri-food system in many countries, due to rapid growth driven by food processing, packaging, transport, retail, household consumption, waste disposal and the manufacturing of fertilizers, according to a new study led by the Food and Agriculture Organization of the United Nations (FAO).

Factors unrelated to on-farm activities and land-use changes already account for more than half of the carbon dioxide emissions from agri-food systems in advanced regions and their share has more than doubled over the past three decades in developing countries.

The new study, available as a pre-print today in Earth Systems Science Data Discussions  and authored by FAO senior statistician Francesco Tubiello, builds on a wave of recent efforts to quantify GHG trends in order to facilitate mitigation measures and alert policy makers to emerging trends. Importantly, the data base, relative to 236 countries and territories over the period 1990-2019 and to be updated annually, can now be easily accessed and used through the FAOSTAT portal, offering details across all agri-food systems components. This makes it easier for farmers and ministerial planners to understand and for countries to better understand the connections between their planned climate actions under the Paris Agreement.

Ultimately, it can be used to help consumers to understand the full carbon footprint of particular commodities across global supply chains.

“FAO is glad to offer this global public good, a data set that directly and in detail addresses the greatest challenge of our time and which is now available for all,” said FAO Chief Economist Maximo Torero. “This kind of knowledge can spur meaningful awareness and action.”

The new data find that 31 percent of total anthropogenic GHG emissions, or 16.5 billion tonnes, originate from the world’s agri-food systems, a 17 percent increase from 1990, when the global population was smaller. The global shares are in line with previous work, indicating a range between 21-37%.

The new report, using a broader data set and more granular approach outlined in an analytical brief, found in addition that agri-food system emissions from land use changes – such as turning forests into cropland – while still one of the most important determinant of agri-food systems emissions, decreased by 25 percent over that time, while emissions within the farm gate increased by only 9 percent. That highlights how supply-chain factors are driving the increase in overall agri-food system GHG emissions.

“The most important 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 food supply chains, at all scales form global, regional and nation,” says Tubiello. “This has important repercussions for food-relevant national mitigation strategies, considering that until recently these have focused mainly on reductions of non-CO2 within the farm gate and on CO2 from land use change.”

The release of this new data set, presented Monday at COP26, is instrumental for the discussions countries are having at the climate summit in Glasgow, as well as enabling targeted implementation of some of the pledges countries make to pursue carbon neutrality.

The UN Statistics Division (UNSD), the International Energy Agency (IEA), and researchers from Columbia University and the Potsdam Institute for Climate Impact Studies collaborated with FAO in the recent analysis.

Tracking facts, finding trends

Of the 16.5 billion tonnes of GHG emissions due to global total agri-food systems emissions in 2019, 7.2 billion tonnes came from within the farm gate, 3.5 from land use change, and 5.8 billion tonnes from supply-chain processes.

The latter category already emits the most carbon dioxide, the key metric as it accumulates, while on-farm activities were by the far the major emitters of methane (CH4) and nitrous oxide (N2O), although food waste decay generates significant amounts of methane.

In terms of singular components, in 2019 deforestation was the largest source of GHG emissions, at 3,058 Mt CO2, followed by enteric fermentation (2,823 Mt CO2eq), livestock manure (1,315 Mt CO2eq), household consumption (1,309 Mt CO2eq), food waste disposal (1,309 Mt CO2eq), on-farm use of fossil fuels (1,021 Mt CO2eq), and the food retail sector (932 Mt CO2eq).

While the first component is declining and the second one growing only modestly, emissions from retail – including fluorinated “F gases” associated with refrigeration and with far more powerful climate impacts than CH4 or N02 - have increased by more than sevenfold since 1990 while those from household consumption have more than doubled.

Agri-food system GHG emissions from Asia, the world’s most populous region, are far and away the greatest, followed by Africa, South America, Europe, North America and Oceania.

However, the study found that GHG missions from pre- and post-production phases of the food supply chain accounted for more than half of the agri-food system total in both Europe and North America, while the figure was below 14 percent for Africa and South America.

Variation is marked at a country level. For example, the food-system GHGs due to land use change were negligible in China, India, Pakistan, the Russian Federation and the United States of America, but were the dominant component in Brazil, Indonesia and the Democratic Republic of Congo. Within the supply chain, household consumption processes were the leading source of GHG emissions in China, food waste disposal the dominant pathway in Brazil, Democratic Republic of Congo, Indonesia, Mexico and Pakistan, while the retail sector dominated in the U.S, Russia and Canada. On-farm energy use was the largest source for India.

Such variation points to different potential mitigation strategies and also to likely trends in the future. For example, while food-system emissions as a share of the total has declined globally from 40 percent in 1990 to 31 percent in 2019, the story in regions dominated by modern agri-food systems was the opposite: They rose from 24 percent to 31 percent in Europe and from 17 percent to 21 percent in North America. Notably, this emission growth was driven by carbon dioxide, confirming the growing weight of pre- and post-production processes which typically involve fossil-fuel energy use.