Abstract
Animal husbandry, aquaculture and fishery have major impacts on the environment. In order to identify the range of impacts and the most important factors thereof, as well as to identify what are the main causes of the differences between products, we analysed 52 life cycle assessment studies (LCAs) of animal and vegetal sources of protein. Our analysis was focused only on land requirement and carbon footprints. In a general conclusion it can be said that the carbon footprint of the most climate-friendly protein sources is up to 100 times smaller than those of the most climate-unfriendly. The differences between footprints of the various products were found mainly to be due to differences in production systems. The outcomes for pork and poultry show much more homogeneity than for beef and seafood. This is largely because both beef and seafood production show a wide variety of production systems. Land use (occupation), comprising both arable land and grasslands, also varies strongly, ranging from negligible for seafood to up to 2100 m² y kg-¹ of protein from extensive cattle farming. From farm to fork the feed production and animal husbandry are by far the most important contributors to the environmental impacts. © 2012 Elsevier Ltd. All rights reserved.
Generated Summary
This review article analyzes 52 life cycle assessment (LCA) studies to evaluate the land use and carbon footprints associated with animal food products and their substitutes. The study identifies the range of environmental impacts, key influencing factors, and the main causes of differences between various protein sources. The research focused on land use (occupation) and greenhouse gas emissions, given their significance to ecosystem damage and biodiversity loss. The methodology involved reviewing published LCA studies on meat, milk, seafood, and other protein sources, with the aim of comparing land requirements and carbon footprints, identifying important inputs and processes in the life cycles, and determining the main causes of observed differences. The studies were published between 1998 and 2011, with most data from the late 1990s to 2005. The results were converted to kilograms of boneless retail meat for comparability.
Key Findings & Statistics
- The carbon footprint of climate-friendly protein sources can be up to 100 times smaller than that of the most climate-unfriendly sources.
- Land use (occupation) ranged from negligible for seafood to up to 2100 m² y kg-¹ of protein from extensive cattle farming.
- The most climate-friendly protein sources have carbon footprints that are many times smaller than those of the ‘worst case’ sources.
- The range in land use is even larger, from less than 10 m² y kg-¹ protein for vegetal products and meat substitute with egg protein to over 2000 m² y kg-¹ for meat from extensively farmed ruminants.
- Beef (15 studies, n = 26): Carbon footprint (kg CO2-eq kg-1): 9-129, Land use (m² y kg-1): 7-420, Of which grassland (m² y kg-¹): 2-420.
- Pork (eight studies, n = 11): Carbon footprint (kg CO2-eq kg-1): 4-11, Land use (m² y kg-1): 8-15
- Poultry (four studies, n = 5): Carbon footprint (kg CO2-eq kg-1): 2-6, Land use (m² y kg-1): 5-8
- Milk (12 studies, n = 14): Carbon footprint (kg CO2-eq kg-1): 1-2, Land use (m² y kg-1): 1-2, Of which grassland (m² y kg-¹): ca 1.
- Meat substitutes, 100% vegetal (one study, n = 4): Carbon footprint (kg CO2-eq kg-1): 1-2, Land use (m² y kg-1): 2-3
- Carbon footprint of the beef from culled dairy cows is low compared to that from beef cattle.
- The carbon footprint of organic pork is 20% higher than that of conventional pork.
- In a study by the FAO (2010), an average of 1.3 kg CO2-eq kg-¹ is calculated for western Europe.
- Pork shows a medium carbon footprint.
- Pork (20% protein) has a carbon footprint of 20-55 kg CO2-eq kg-1 retail meat, and land use of 40-75 m2 y kg-1 protein.
- Poultry (20% protein) has a carbon footprint of 10-30 kg CO2-eq kg-1 protein, and land use of 23-40 m2 y kg-1 protein.
- Meat substitutes, 100% vegetal (8-20% protein) has a carbon footprint of 6-17 kg CO2-eq kg-1 protein, and land use of 4-25 m2 y kg-1 protein.
Other Important Findings
- Differences in carbon footprints between products are largely due to variations in production systems.
- The outcomes for pork and poultry are more homogeneous than for beef and seafood, largely because beef and seafood production have a wider variety of production systems.
- Feed production and animal husbandry are the most important contributors to environmental impacts from farm to fork.
- The process of fermentation in the rumen of ruminants produces the greenhouse gas methane, a main reason for the high carbon footprint of beef and lamb.
- The environmental impact of beef from culled dairy cows is lower compared to beef cattle due to the relative efficiency of meat and milk co-production in intensive systems.
- For pork, nitrous oxide emissions from feed production and for beef, the methane emission from enteric fermentation are by far the most important emissions.
- In the life cycle of vegetal meat substitutes, crop production and energy use in food processing are the most important contributors.
- Shifts in consumption from red meats and high-impact seafood to vegetal protein, white meats, and sustainable seafood products, as well as improved management within production chains, can offer significant mitigation potential.
Limitations Noted in the Document
- Methodological differences between LCA studies may limit comparability.
- The study primarily focuses on land use and carbon footprints and does not fully address other environmental impacts like animal welfare.
- The study relies on average data and does not account for regional variations or dynamic changes in agricultural and fishing yields.
- The study does not include LCA of promising new products such as laboratory meat or insect protein, as there are no or little LCA studies available.
- The study uses default factors for important emissions of N2O from fertilized soils rather than actual emission based on measurements.
- The inclusion of changes in soil organic carbon (SOC) and the consequent blocking of the natural build-up of soil organic carbon by permanent land use may have significant effects on the outcomes.
Conclusion
The analysis of 52 LCA studies reveals that animal-based food products, particularly ruminant meats, have significantly higher environmental impacts than plant-based alternatives. The research highlights the substantial variability in carbon footprints and land use across different protein sources, with production systems playing a critical role in these differences. The study underscores the importance of considering both greenhouse gas emissions and land use when evaluating the environmental impacts of food products. The findings suggest that shifts in dietary choices, favoring plant-based proteins, poultry, and sustainable seafood, could lead to substantial environmental benefits. The study emphasizes the need for improved management within production chains to further reduce the impacts of animal agriculture. It also highlights the potential for reducing the environmental impacts of food consumption. The research also points out the potential in a shift in consumption patterns and improved management within production chains for lowering the carbon footprint. Moreover, the results point to the need for additional research to clarify the environmental impact of new protein sources and refine LCA methodologies for agricultural products. Finally, the study concludes that while there is a large potential for improvement and mitigation, significant shifts in consumer behavior and production practices are necessary to achieve meaningful reductions in the environmental impact of the food system.