Greenhouse gas (GHG) emissions due to land-use changes such as converting forests to agricultural land have been decreasing over the past 20 years, a decline that has been counterbalanced by increased emissions — notably high in industrialised countries — from off-farm activities before and after food production according to a new study led by the Food and Agriculture Organization of the United Nations (FAO) and published today in Environmental Resource Letters.
The report, “Greenhouse Gas Emissions from the Food System: Building the Evidence Base“, estimates that food-system emissions amounted to 16 billion tonnes of carbon dioxide or equivalents (CO2eq) in 2018, an 8 per cent increase since 1990. They now represent 33 per cent of all human-caused GHG emissions.
That, lead author Francesco Tubiello, a senior statistician and climate change specialist at FAO, highlights how the global food system represents a “larger GHG mitigation opportunity than previously estimated and one that cannot be ignored in efforts to achieve the Paris Agreement goals”.
Governments around the world are pledging to reduce their GHG emissions and pursue carbon neutrality, and many have included mitigation targets for their agriculture sectors in their national plans. However, action in food and agriculture goes well beyond impacts on farms and ecosystems. Analysing emissions trends through the broader lens of food systems offers additional insights and opens a range of possible solutions across the entire food production and consumption chain.
The new study provides rich data sets that are being refined ahead of the UN’s Food Systems Summit 2021, with important components already available for consultation here. It considers GHG emissions linked to farm gate production, land-use change at the boundary between farms and natural ecosystems, and supply chains including consumption and waste disposal, to offer a crisper and more granular assessment of trends at the global, regional and country levels.
Over recent decades food systems emissions, both in absolute and per-capita levels, are increasingly dominated by farm gate and supply chains processes, with the impacts from land-use change decreasing as economies develop. Furthermore, the study highlights important differences among countries, with developed economies per capita food systems emissions nearly twice those in developing countries.
Finally, the study offers an operational map to better identify food-relevant components in the national emissions plans communicated to the United Nations Framework Convention on Climate Change using Intergovernmental Panel on Climate Change (IPCC) categories. Currently, countries report data in their Nationally Determined Contributions but lack a proper quantification of food systems emissions within National Greenhouse Gas Inventories (NGHGIs).
The research team that compiled the study also consists of experts from Columbia University and NASA, several UN agencies and numerous policy-focused research centres.
The open-access report, which builds on another recent data-rich FAO study, offers the full spectrum of technical findings, and represents an important step for building a full database within FAOSTAT.
One emergent theme is that optimal GHG mitigation strategies require a focus on activities before and after farm production, ranging from the industrial production of fertilisers to refrigeration at the retail level, as this is the area where emissions are growing fastest - due in part to a slowdown in deforestation.
Key findings
In 2018, GHG emissions from food systems were more than 16 billion tonnes CO2eq, largely emitted in developing countries in terms of absolute amounts.
Global per capita emissions, which decreased from 1990 to 2010 from 2.9 to 2.2 tonnes CO2eq, were characterised by important differences between developed and developing economies. Per capita emissions in developed countries, at 3.6 tonnes CO2eq in 2018, were nearly twice those in developing countries.
Farm-gate and pre and post-production emissions (those largely along supply chains, consumption and waste) represented two-thirds of the food systems total in 2018, with the role of emissions from land-use change having decreased over time.
On agricultural land — crop and livestock processes within the farm gate but also including relevant land-use changes — amounted to 10.4 Gt of CO2eq, 80 per cent of which occurred in developing countries. That represents a 3 per cent decline from 1990, as increased on-farm emissions of nitrous oxide and methane were more than offset by a decrease in emissions from land-use change such as deforestation or peatland degradation.
Net forest conversion — from natural ecosystems to agricultural croplands or pastures, a proxy for deforestation — remained the largest GHG emission source over this period, at nearly 3 billion tonnes CO2 per year, but declined significantly over time, by over 30 per cent from 1990 to 2018.
The new analysis adds detailed country data estimates on domestic food transportation, which emitted globally a mere 0.5 Gt CO2eq in 2018, but have increased by nearly 80 per cent since 1990, and nearly tripled in developing countries.
GHGs generated by energy use - largely carbon dioxide from fossil fuels - along the supply chain amounted to over 4 Gt CO2eq in 2018, an increase of 50 per cent since 1990.
The FAO-led study also characterises country-level emissions from food waste disposal, half of which consist of methane, reaching globally nearly 1 Gt CO2eq in 2018.
What to do?
The declining trend of GHGs linked to land-use change is welcome, but points to the importance of maintaining and even accelerating the good progress achieved in recent years, while focusing on designing climate-friendly practices along the whole food supply chain including — the authors note — the critical role that dietary choices and consumption patterns can play by impacting supply-side production activities.
Assessing the data and trends from a food-systems perspective points to some immediately actionable pathways - such as improving nitrogen use efficiencies in crop and livestock production, mitigating solid food waste disposal and optimising on-farm energy use - as well as accelerated efforts to improve management of agricultural land while protecting natural ecosystems.
They also underscore that energy use beyond the farm gate will become an increasingly prominent component of total food-system GHG emissions in the coming decades, so that food-related mitigation can benefit from a whole-system view and broader planning at the national level.
“The goal is to complement current emissions on agricultural land with significant carbon removals, based on improved landscape management and more efficient production, thus advancing a carbon-neutral food system,” says Tubiello.
This story was published with permission from UNFAO.
