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PARIS: Scientists have warned that greenhouse gas emissions from the global food system are likely to cause an increase in Earth’s surface temperatures of nearly one degree Celsius by 2100, exceeding the Paris Agreement’s climate goals.
They reported in Nature Climate Change that a major overhaul of the sector – from production to distribution to consumption – could cut emissions by more than half even as the global population grows.
Since the late 1800s, the Earth’s surface has warmed by 1.2 degrees Celsius, leaving only a narrow margin for staying within the 2015 treaty’s core goal of keeping warming “well under” 2 degrees Celsius.
Even further out of reach is the aspirational limit of 1.5 degrees Celsius, which science later demonstrated to be a much safer threshold for avoiding devastating and potentially irreversible climate impacts such as coastal flooding, heatwaves, and drought.
“Mitigating emissions from the food sector is critical to working towards a secure climate future,” study lead author Catherine Ivanovich, a doctoral student at New York’s Columbia University, told AFP.
The global food system is responsible for approximately 15% of current warming levels, but only one-third of national emissions reduction plans under the Paris pact include any measure to reduce carbon pollution from agriculture or livestock.
Ivanovich and her colleagues looked separately at the three main greenhouse gases, which vary in potency and staying power in the atmosphere, to improve on previous estimates of how much feeding the world contributes to global warming.
Carbon dioxide, once emitted, remains in the atmosphere for centuries. Methane only lasts about a decade but is nearly 100 times more efficient at retaining the Sun’s heat on that timescale.
Dietary modifications
Methane from belching livestock, rice paddies, and rotting food accounts for roughly 60% of food-related emissions, they discovered, with CO2 from machinery and transportation, as well as nitrous oxide from excessive use of chemical fertilizers, accounting for 20% each.
The researchers also gathered information on the carbon footprints of nearly 100 different food items.
The study concluded that unless production and diet drastically change, global food consumption will raise Earth’s average surface temperature by 0.7 to 0.9 degrees Celsius by the end of the century.
“On its own, this additional warming is sufficient to exceed the 1.5C global warming target and approach the 2C threshold,” the authors wrote.
According to the study, methane is clearly the key to reducing food-related carbon pollution.
“The majority of future warming from the food sector is due to methane emissions,” said Ivanovich.
“Because it is a short-lived pollutant, immediate reductions in its emissions can result in near-term climate benefits.”
Improving meat, dairy, and rice production methods alone could cut the additional warming forecast from the food sector by a quarter, she said.
Adopting a diet that is optimal for human health around the world, using renewable energy instead of fossil fuels, and reducing food waste would save another 25%, according to the study.
However, other research has shown that trend lines for many of these measures are stagnant or, in the case of meat consumption, moving in the wrong direction.
