Abstract
Food consumption is a major source of greenhouse gas (GHG) emissions, and evaluating its future warming impact is crucial for guiding climate mitigation action. However, the lack of granularity in reporting food item emissions and the widespread use of oversimplified metrics such as CO₂ equivalents have complicated interpretation. We resolve these challenges by developing a global food consumption GHG emissions inventory separated by individual gas species and employing a reduced-complexity climate model, evaluating the associated future warming contribution and potential benefits from certain mitigation measures. We find that global food consumption alone could add nearly 1 °C to warming by 2100. Seventy five percent of this warming is driven by foods that are high sources of methane (ruminant meat, dairy and rice). However, 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.
Generated Summary
This research investigates the future warming impact of global food consumption, emphasizing the need for climate mitigation strategies within the food sector. The study employs a reduced-complexity climate model to evaluate the contributions of individual greenhouse gases (GHGs) and food groups to warming, considering various population projections. The methodology involves developing a detailed inventory of GHG emissions from current food consumption, scaling these emissions over time based on population projections, and modeling their impact on surface air temperature. The research also explores potential benefits from demand- and supply-side interventions, such as modifications to production practices, dietary changes, and reductions in food waste. This comprehensive approach aims to provide insights into the relative importance of different food sources and GHGs in driving climate change, guiding effective policy design and mitigation efforts. The use of a reduced-complexity climate model (MAGICC) enables the assessment of temperature responses over time and the identification of impactful mitigation strategies, offering a more nuanced understanding than traditional metrics like Global Warming Potential (GWP).
Key Findings & Statistics
- Global Food Consumption Emissions in 2010:
- CO2: 4,860 million tonnes (Mt)
- CH4: 151 Mt
- N2O: 9 Mt
- Projected Warming by 2100:
- Business-as-usual food consumption could add nearly 1°C to warming by 2100.
- Range: 0.7 ± 0.2°C to 0.9 ± 0.2°C above present-day warming levels, depending on population growth.
- Contributions to Warming:
- Methane (CH4) is responsible for nearly 60% of the warming by the end of the century.
- CO2 and N2O each account for about 20% of the end-of-century warming.
- Food Group Contributions to Warming:
- Ruminant meat, dairy, and rice are major contributors.
- Dairy and meat consumption responsible for over half the warming by 2030 and through 2100.
- Rice contributes a large fraction of end-of-century warming (19%).
- Mitigation Potential from Production Practices:
- Improvements in production practices could avoid -0.2°C warming.
- Maximum potential decreases of roughly 35%, 30%, and 10% in total CO2e100 emissions associated with ruminant meat, dairy, and non-ruminant meat, respectively.
- Rice exhibits the potential for a 50% decrease in methane emissions.
- Mitigation Potential from Decarbonization of Energy Sector:
- Decarbonization of the energy sector would decrease end-of-century warming by ~17% (additional 0.15°C).
- Mitigation Potential from Dietary Changes:
- Adoption of healthier diets could decrease warming by 0.19°C by the end of the century.
- This amounts to -21% of the anticipated warming due to sustained dietary consumption rates.
- Mitigation Potential from Food Waste Reduction:
- Cutting retail and consumer food waste in half could decrease end-of-century warming by 0.04°C (~5%).
- Combined Mitigation Potential:
- Simultaneous implementation of production improvements, decarbonization, healthy diets, and reduced food waste could avoid 0.5°C of additional future warming by 2100.
- This is more than 55% of the anticipated warming from sustaining global food consumption.
- Emissions Inventory and Breakdown:
- Emissions data disaggregated for 94 food items.
- 206 estimations of individual gas breakdowns for each food item or group.
- Impact of Methane Emissions:
- Methane emissions account for 73% of the additional temperature increase from food by midcentury.
- 60% of the additional temperature increase from food by the end of the century.
Other Important Findings
- The study highlights the significant contribution of the food sector, particularly meat, rice, and dairy, to future warming.
- The research emphasizes the limitations of using simple metrics like CO2 equivalents and the need for detailed analysis of individual GHGs.
- The analysis underscores that current dietary patterns and agricultural practices are unsustainable in terms of climate change.
- The study identifies specific mitigation strategies, including improvements in production practices, dietary changes, and waste reduction, which could substantially reduce future warming.
- The study notes that a multi-scale approach, involving both supply- and demand-side interventions, is essential for effective climate mitigation.
- The research provides a detailed database of food consumption emissions, disaggregated by individual gases and food items, which can be used for further analysis.
- The findings suggest that targeting high-methane food groups can rapidly benefit the climate, given the relatively short lifespan of methane.
- The study points out that current mitigation efforts in agriculture, particularly regarding livestock and rice, are insufficient and need to be scaled up.
- The analysis found that the warming from the consumption of dairy and meat is responsible for more than half of the warming by the year 2030 and through to the year 2100.
Limitations Noted in the Document
- The study acknowledges uncertainties in the underlying data, including standard uncertainties in modeling climate responses and limitations in available GHG emissions data.
- The analysis is based on the assumption of sustained dietary patterns, which may not reflect future changes in consumption habits.
- The study relies on a reduced-complexity climate model (MAGICC), which, while reliable, still has limitations in representing complex climate processes.
- The study’s reliance on average GHG emissions from the FAO food balance sheets and the use of average food waste rates introduces uncertainty.
- The analysis focuses primarily on retail and consumer-level food waste, not considering food loss throughout the entire production chain.
- The potential for land use limitations on future food production is not considered.
- The study uses estimates from Poore and Nemecek, which may overestimate or underestimate the emissions of individual GHGs, which may impact the results.
Conclusion
The research presented offers a detailed and comprehensive assessment of the climate impacts of global food consumption, emphasizing the urgent need for sustainable practices. The study’s findings clearly indicate that current dietary patterns, characterized by a significant reliance on meat, rice, and dairy, are unsustainable and will lead to substantial warming in the coming decades. The study reinforces the urgency of implementing effective mitigation strategies to curb these emissions. “We found that sustaining current dietary patterns worldwide throughout the rest of the century could amount to nearly 1 °C of additional warming.” The research highlights a multi-faceted approach, integrating technological advancements in production, decarbonization of the energy sector, dietary shifts towards healthier and more sustainable choices, and a significant reduction in food waste. These combined efforts could lead to a considerable decrease in future warming, offering a realistic path towards a more sustainable food system. The key benefit of our approach in disaggregating GHG emissions from food consumption by gas is that it allows the use of a climate model to evaluate temperature responses to food consumption and has a significant impact on climate change mitigation. The study’s detailed methodology and comprehensive database of emissions provide a robust foundation for future research and policy decisions. “The key benefit of our approach in disaggregating GHG emissions from food consumption by gas is that it allows the use of a climate model to evaluate temperature responses to food consumption… This bias is particularly critical since methane is responsible for the majority of future warming from the food sector.” This research demonstrates the importance of taking action, including prioritizing actions to reduce agricultural GHG emissions.