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Greenhouse gas (GHG) emissions due to land use changes decreasing over the past 20 years
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Experts call for complementing emissions on agri land with more efficient production
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 study by Food and Agriculture Organization (FAO) of the United Nations said.
But this welcome decline has been counterbalanced by increased emissions from off-farm activities before and after food production, especially in industrialized countries, said the study published in Environmental Resource Letters.
The study, “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 percent increase since 1990. They now represent 33 percent 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”.
The study said global per capita emissions, which decreased from 1990 to 2010 from 2.9 to 2.2 tonnes CO2eq, were characterized 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 percent of which occurred in developing countries. That represents a 3 percent 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 percent 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 percent 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 percent since 1990.
The FAO-led study also characterizes 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.
“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.