Greenhouse gas emissions that are produced from the way humans produce and consume food could add nearly 1 degree of warming to the Earth’s climate by 2100, according to a new study published in the journal Nature Climate Change.
Continuing the dietary patterns of today will push the planet past the 1.5 degrees Celsius (2.7 degrees Fahrenheit) limit of warming sought under the Paris climate agreement to avoid the worst effects of climate change, according to this new study, and will approach the agreement’s limit of 2 degrees Celsius (3.6 degrees Fahrenheit).
The modeling study found that the majority of greenhouse gas emissions come from three major sources: meat from animals, especially ruminant animals (e.g., cows, sheep); rice; and dairy. Those three sources account for at least 19% each of food’s contribution to a warming planet, according to the study, with meat contributing the most, at 42% (ruminant meat = 33%; non-ruminant meat = 9%). See the Figure below.
Methane is a potent greenhouse gas with more than 80 times the warming power of carbon dioxide. The researchers calculated that methane will account for 75% of food’s share of warming by 2030, with carbon dioxide and nitrous oxide accounting for most of the rest.
“I think the biggest takeaway that I would want (policymakers) to have is the fact that methane emissions are really dominating the future warming associated with the food sector,” said Catherine C. Ivanovich, a climate scientist at Columbia University and the study’s lead author.
Ivanovich and colleagues from the University of Florida and Environmental Defense Fund calculated the three major gases produced by each type of food over its lifetime based on current consumption patterns. Then they scaled the annual emissions over time by gas based on five different population projections.
And then they used a climate model frequently used by the United Nations’ panel on climate change to model the effects of those emissions on surface air temperature change.
“The study highlights that food is absolutely critical to hitting our Paris Agreement climate targets — failure to consider food is failure to meet our climate targets globally,” said Meredith Niles, a food systems scientist at the University of Vermont who was not involved in the study.
Multiple recent studies and reports have recommended eating less meat in order to reduce greenhouse gas creation by animals raised for consumption. Reducing methane may be the most important goal of all. Although methane is far more potent than carbon, it also is much shorter-lived — meaning cuts in methane emissions can have a quick benefit, Ivanovich, the lead study author, said.
Food-related temperature rise could be curbed, the researchers said. If people consumed red meat only once a week (a single serving), such as what is outlined in the EAT-Lancet planetary health diet, the rise could be cut by 0.2C. Such a diet would mean a big cut in meat eating in wealthy countries but could mean an increase in meat consumption in some poorer countries. For more information on implementing sustainable diets, see this 10-minute interactive guide to a Healthy Plate and a Healthy Planet, which is available at: https://www.gaplesinstitute.org/sustainable-diets/
Cutting methane emissions from cattle using feed additives and better management of manure could avoid another 0.2C, the researchers said, while switching to green energy in the food system would cut 0.15C. Ivanovich said the emissions reductions options included in the study were those possible today but that future technological advances might be able to reduce emissions further.
“We already know that livestock production has a disproportionate contribution to climate change – even using traditional metrics, in 2021 we showed that 57% of emissions from the food system arise from animal agriculture,” said Prof Pete Smith, at the University of Aberdeen, UK. “This very neat study uses a simple climate model to show the disproportionate impact of methane emissions from agriculture on temperature increases, and throws light on the importance of reducing methane emissions from the food system.”
“Only a third of the world’s countries have included policies to cut emissions from agriculture in the climate plans they have submitted under the UN Paris Climate agreement. The researchers said their work was aimed at increasing the understanding of the impact of global food consumption on future global heating. Ivanovich also said policies to cut emissions had to protect access to food and livelihoods for vulnerable populations.”
References
Ivanovich, C.C., Sun, T., Gordon, D.R. et al. Future warming from global food consumption. Nature Climate Change. 13, 297–302 (2023). https://doi.org/10.1038/s41558-023-01605-8.
Costly D. The way we eat could add nearly 1 degree of warming by 2100. Associated Press. March 6, 2023. Available at: https://apnews.com/article/climate-agriculture-food-methane-emissions-3980deda0d27c16258c1e79bbf4e1481
Carrington D. Meat, dairy and rice production will bust 1.5C climate target, shows study. March 6, 2023. The Guardian. Available at: https://www.theguardian.com/environment/2023/mar/06/meat-dairy-rice-high-methane-food-production-bust-climate-target-study
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