The study of 171 crops and 16 animal products in 200 countries found that food production accounts for more than a third (35 per cent) of global greenhouse gas emissions – higher than previous estimates had suggested.
Meat and dairy products account for 57 per cent of total food emissions, whereas plant-based foods cause 29 per cent, the analysis found. The remaining emissions are driven by other products such as cotton and rubber.
Beef was found to be the most polluting meat product – accounting for a quarter of all animal-based food emissions.
“Our study results show that food production is already generating more than one-third of total greenhouse gas emissions,” Prof Atul Jain, a climate and land use scientist from the University of Illinois at Urbana-Champaign, told The Independent.
“Our results show food production’s current contribution to total greenhouse gas emissions is 17 billion metric tonnes of CO2 equivalent per year, or 35 per cent of global total man-made greenhouse gas emissions.
“Beef is the largest contributing animal-based food, followed by cow’s milk and pork.”
The study, published in the journal Nature Food, adds to a wide body of evidence showing that the production of animal-based foods, particularly red meat, is a leading driver of the climate crisis.
Using data from 2010, the research considers all stages of food production – from when land is cleared to make space for livestock or crops to when food products are processed and transported.
It considers how food production drives emissions of the three main greenhouse gases: CO2, methane and nitrous oxide.
The production of meat and dairy is a particularly large driver of all three of these greenhouse gases to be released.
For example, the clearance of forested land to graze cattle or grow animal feed causes large amounts of CO2 to be released.
In addition, cows, sheep and goats are “ruminants” – meaning they belch out large amounts of methane when digesting food.
As well, nitrous oxide emissions are caused by livestock manure and the use of nitrogen fertilisers during the production of animal feed.
Some plant-based foods are also particularly polluting.
The study found that the production of rice is a particularly large driver of methane. This is because rice is mostly grown in flooded fields called rice paddies, which create the ideal conditions for methane-emitting bacteria.
The research also examines how emissions from food production differ around the world.
The findings show that south and southeast Asia causes more pollution than any other world region, accounting for nearly a quarter (23 per cent) of all food production emissions.
However, food emissions in this region are much lower when considered per person, the study added.
The second largest emitter is South America, which also has the greatest emissions per person out of any world region, the study said.
Overall, the findings show that more action is needed to address the climate impact of the world’s food system, said Prof Jain.
“Policymakers should develop strategies to control greenhouse gas emissions from fossil fuel burning and other sources and the production – and consumption of total and individual plant and animal-based foods,” he said.
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