Food system emissions on track to drive world past 1.5C global warming limit, warns research

08 Mar 2023 --- Food consumption is a significant source of greenhouse gas (GHG) emissions, and evaluating its future warming impact is crucial for guiding climate mitigation action. New research has revealed that emissions from the food system alone are expected to drive the world past 1.5C of global heating, underscoring the need to further tackle the consumption and production of high-methane foods such as dairy and meat.

According to a peer-reviewed study from Columbia University, US, global food consumption could add almost 1°C to warming by 2100.

Key findings show 75% of this warming is driven by foods that are high sources of methane, such as meat, dairy, and rice.

However, the researchers express that over 55% of anticipated warming can be avoided from simultaneous improvements to production practices, the universal adoption of a healthy diet, and consumer- and retail-level food waste reductions.

A high percentage of this warming is driven by foods that are high sources of methane, such as meat, dairy and rice.Similarly, as inflation and the cost of living crisis continue to take their toll on consumers, a recent report by anti-waste NGO WRAP published earlier this week suggested that excessive portion sizes in meals ordered out of home fuel consumer concerns about food waste, sustainability and cost.

Food supply chains
Food is both an essential aspect of life and a significant source of GHG emissions. The agriculture sector is responsible for nearly half of the methane (CH4) emissions, two-thirds of nitrous oxide (N2O) emissions and 3% of carbon dioxide (CO2) emissions from human activities worldwide.

Carbon dioxide is emitted throughout the food supply chain from energy use from cultivation machinery and product transportation.

Previous studies have shown the significant impact of food production on the environment, particularly meat and dairy. Still, the new research published in Nature provides estimates of the temperature rises their emissions could cause.

However, this could be a significant underestimate as the study assumed animal product consumption would remain level in the future but was projected to rise by 70% by 2050.

Animal products and rice under fire
Methane is emitted primarily from animal products and rice production through enteric fermentation, manure management and rice paddy methanogenesis. Nitrous oxide can trap more than 250 times more heat than CO2 by mass, lasts around a century and is emitted through synthetic fertilizer use, the cultivation of nitrogen-fixing crops and ruminant excretion on rangelands.

“Methane has this really dominant role in driving the warming associated with the food systems,” says Catherine Ivanovich, who led the research at Columbia University. “Sustaining the pattern we have today is inconsistent with keeping the 1.5C temperature threshold. That places a lot of urgency on reducing the emissions, especially from the high-methane food groups.”

“We have to make the goal of sustaining our global population consistent with a climate-safe future.”

Tackling dietary consumption patterns
In the analysis, researchers estimate the future warming impacts of sustaining current global dietary consumption patterns throughout the 21st century using a reduced-complexity climate model. Based on an extensive literature review, they develop a detailed inventory of individual GHG emissions from current food consumption.

The researchers then scale annual emissions over time by gas based on five population projections and model the impacts of these emissions on surface air temperature change using the reduced-complexity Model for the Assessment of Greenhouse Gas Induced Climate Change (MAGICC).

The researchers aggregated the emissions from each food item into 12 food groups: grains, rice, fruit, vegetables, ruminant meat, non-ruminant meat, seafood, dairy, eggs, oils, beverages and other.

They found that the consumption of dairy and meat will be responsible for more than half of the warming by 2030 and over the next 77 years.Methane is emitted primarily from the production of animal products and rice.

Of the other food groups, rice contributes to a large fraction of end-of-century warming (19%). In contrast, vegetables, grains, seafood, oils, beverages, eggs, fruit and all other uncategorized food items each contribute 5% or less.

However, they note that the dominance of meat, rice and dairy products toward the total climate impact of food consumption measured by these metrics is consistent.

What would happen if healthier diets were adopted?
The researchers also considered changes to dietary behaviors by analyzing the potential avoided warming associated with the universal adoption of healthier diets.

Previous studies have found that there may be synergies between actions associated with improving health and those associated with reducing GHG emissions intensity, and a health-driven mission may be more likely to be adopted on a global scale than changes in dietary behavior in response to environmental concerns.

Dietary recommendations provided by the Harvard Medical School, which focus on reduced meat intake, specifically prescribe the sparing consumption of red meat and the limited consumption of fish, poultry and eggs.

The researchers found that if these dietary changes were implemented globally, warming due to food consumption could be decreased by 0.19 °C by the end of the century, consistent with previous literature highlighting the potential for dietary recommendations to provide environmental as well as health benefits.

Meanwhile, sustainability factors are increasingly influencing the purchasing behavior of European consumers, according to a recent study published by crop nutrition company Yara International via IPSOS. Consumers are willing to pay more for greener products and want producers to provide better climate-related on-label packaging.

Last month, World Pulses Day recognized the potential of pulses to help achieve the 2030 Agenda for Sustainable Development. The annual day was marked amid a greater focus on food sources, better nutrition and the planet’s health.

By Elizabeth Green

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