Low-carbon diet
A low-carbon diet is any diet that results in lower greenhouse gas emissions.[1][2] Choosing a low carbon diet is one facet of developing sustainable diets which increase the long-term sustainability of humanity. Major tenets of a low-carbon diet include eating a plant-based diet, and in particular little or no beef and dairy.[3] Low-carbon diets differ around the world in taste, style, and the frequency they are eaten. Asian countries like India and China feature vegetarian and vegan meals as staples in their diets. In contrast, Europe and North America rely on animal products for their Western diets.[4]
It is estimated that the
Overall trends worldwide
A 2014 study into the real-life diets of British people estimated their
- 7.19 for high meat-eaters (≥100 g/day)
- 5.63 for medium meat-eaters (50–99 g/day)
- 4.67 for low meat-eaters (<50 g/day)
- 3.91 for fish-eaters
- 3.81 for vegetarians
- 2.89 for vegans
While the fish-eaters had the lowest footprints out of all the meat-eaters, the vegetarians and vegans were the lowest overall. This is due to the contribution of greenhouse gases in the growth, processing, production, and transport of the plant-based food products eaten by vegetarians and vegans.[9]
A 2020 study found that Asia has the largest percentage of vegetarians at 19%. Close behind Asia is Africa/the Middle East with 16%. South and Central America have just 8% and North America has a mere 6%. This study found that Europe has the smallest percentage of vegetarians at only 5%.[4] There was not conclusive data on the percentage of vegetarians in Australia.
Non-Western diets are built around unprocessed starches. In South America and Africa, the centerpiece of each meal is beans and grains. Peru, in South America, has potatoes as the foundation for their diet. In Asia, rice is a staple in every household no matter the income level. Meat is usually the centerpiece of meals in the Western diet, whereas animal products are often small parts of the meal (or act as condiments) in the non-Western diet.[10]
In India, the practice of the vegetarian diet is usually generational and simply follows the pattern expected of the family. Adherence can also be credited to certain religious groups and social groups. For example,
Asia includes largely populated countries such as China and India, both of which have thriving Buddhist populations. In China, there are five main influences that contribute to Buddhists keeping vegetarian diets:[12]
- Influence from Mahayana sutras
- Influence of Chinese imperial authority/political figures who promote Buddhism
- Influence of Confucianism
- Influence of Taoism
- Sociocultural influences like societal norms and lived environments
Background on diet and greenhouse gas emissions
In the U.S., the food system emits four of the
Steinfeld et al. estimate that livestock production accounts for 18 percent of anthropogenic GHG emissions expressed as carbon dioxide equivalents.[17] Of this amount, 34 percent is carbon dioxide emission from deforestation, principally in Central and South America, that they assigned to livestock production. However, deforestation associated with livestock production is not an issue in many regions. In the US, the land area occupied by forest increased between 1990 and 2009[18] and a net increase in forest land area was also reported in Canada.[19]
Of emissions they attribute to livestock production, Steinfeld et al. estimate that globally, methane accounts for 30.2 percent. Like other greenhouse gases, methane contributes to global warming when its atmospheric concentration rises. Although methane emission from agriculture and other anthropogenic sources has contributed substantially to past warming, it is of much less significance for current and recent warming. This is because there has been relatively little increase in atmospheric methane concentration in recent years[20][21][22][23] The anomalous increase in methane concentration in 2007, discussed by Rigby et al., has since been attributed principally to anomalous methane flux from natural wetlands, mostly in the tropics, rather than to anthropogenic sources.[24]
Livestock sources (including enteric fermentation and manure) account for about 3.1 percent of US anthropogenic GHG emissions expressed as carbon dioxide equivalents. used in estimating GHG emissions as carbon dioxide equivalents.
A 2016 study published in Nature Climate Change concludes that climate taxes on meat and milk would simultaneously produce substantial cuts in greenhouse gas emissions and lead to healthier diets. Such taxes would need to be designed with care: exempting and subsidising some food groups, selectively compensating for income loss, and using part of the revenue for health promotion. The study analyzed surcharges of 40% on beef and 20% on milk and their effects on consumption, climate emissions, and distribution. An optimum plan would reduce emissions by 1 billion tonnes per year – similar in amount to those from aviation globally.[25][26]
High-carbon and low-carbon food choices
Certain foods require more fossil fuel inputs than others. Animal-based foods like meat and dairy have a much higher carbon footprint than plant-based foods.[6] Therefore, it is possible to go on a low-carbon diet and reduce one’s carbon footprint by choosing foods that need less fossil fuel and therefore emit less carbon dioxide and other greenhouse gases. Further research finds that even "the lowest-impact animal products typically exceed those of vegetable substitutes".[28] For example, Ritchie explains that "producing 100 grams of protein from peas emits just 0.4 kilograms of carbon dioxide equivalents (CO2eq). To get the same amount of protein from beef, emissions would be nearly 90 times higher, at 35 kgCO2eq."[6]
In June 2010, a report from United Nations Environment Programme declared that a global shift towards a vegan diet was needed to save the world from hunger, fuel shortages and climate change.[29] This will mean a huge shift in the diet of the average European, as 83% of their diets are made up of meat, dairy, and eggs.[30] As a major contributor to global carbon emissions, China introduced new dietary guidelines in 2016 which aim to cut meat consumption by 50% and thereby reduce greenhouse gas emissions by 1 billion tonnes by 2030.[31]
More families are choosing to implement vegan and vegetarian diets for adults and children alike. Cundiff and Harris write: "The American Dietetic Association (ADA) and
- Protein (quality and quantity)
- Iron
- Zinc
- Selenium
- Calcium
- Riboflavin
- Vitamins A, D, and B12
- Essential fatty acids
Industrial versus pastured livestock
In one study, grass-fed cattle were estimated to account for 40% less greenhouse emissions than CAFO cattle[7] However, comparative effects on emissions can vary. In a US study, lower GHG emissions were associated with feedlot-finished beef production than with beef production on pasture and hay.[41] Similarly, a study in New Zealand concluded that environmental emissions per kilogram of beef produced can be reduced by incorporating feedlot finishing in a beef production system.[42] Another factor to be considered is the role of a healthy pastoral ecosystem in carbon sequestration.
Because CAFO production is highly centralized, the transport of animals to slaughter and then to distant retail outlets is a further source of greenhouse gas emissions.
In livestock production, emissions are reduced by feeding human-inedible materials that might otherwise by wasted. Elferink et al. state that "Currently, 70% of the feedstock used in the Dutch feed industry originates from the food processing industry."[43] Among several US examples is the feeding of distillers grains remaining from biofuel production. For the marketing year 2009/2010, the amount of dried distillers grains used as livestock feed (and residual) in the US amounted to 25.0 million tonnes.[44]
Distance traveled and method of transit
Carbon emissions from transport account for 11% of the total carbon emissions of food, of which the transportation from producer to consumer accounts for 4%.[45] However, "food miles" are a misleading measure; in many cases food imported from the other side of the world may have a lower carbon footprint than a locally produced equivalent, due to differences in farming methods. "Local food" campaigns may be motivated by protectionism rather than genuine environmentalism.[46]
When looking at total greenhouse gases (not just carbon dioxide), 83% of emissions come from the actual production of the food because of the methane released by livestock and the nitrous oxide due to fertilizer.[45]
The word
Processing, packaging, and waste
Highly processed foods (such as
Bottled water is another example of a highly packaged food product that is considered a single-use plastic because most people discard it after they're done drinking the water. It is estimated that Americans throw away 40 million plastic water bottles every day, and bottled water is often shipped trans-continentally. Carbonated water must be chilled and kept under pressure during storage and transport so as to keep the carbon dioxide dissolved. This factor contributes greater energy usage for products shipped longer distances.
A 2023 study by Siddiqui S. A., et al.[48] evaluated the quality of biodegradable packaging versus conventional plastic packaging for the meat packaging industry in the European Union. Conventional plastic packaging is known for being very flexible and able to stretch greatly during processing, shipping, and handling. With easily customizable production and relatively low cost, plastic packaging is picked most often over glass, cardboard, and other sustainable packaging materials. This study researched which types of biodegradable packaging are the most heat-resistant as well, as plastic has tested superior in this aspect in the past. The future of sustainability with low-carbon production for food packaging rides on biodegradable packaging. Cellulose-based packaging was highly effective at controlling moisture within meat packages in the EU and was able to prevent oxygen from entering. Polyhydroxyalkanoates and polylactic acid (PLA) are examples of sustainable food packaging materials that are considered better than plastic, but could actually be harmful because they may contain chemical additives.
See also
References
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Scarborough, Peter; Appleby, Paul N.; Mizdrak, Anja; Briggs, Adam D.M.; Travis, Ruth C.; Bradbury, Kathryn E.; Key, Timothy J. (July 2014). "Dietary greenhouse gas emissions of meat-eaters, fish-eaters, vegetarians and vegans in the UK". Climatic Change. 125 (2): 179–192. PMID 25834298.
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Springmann, Marco; Mason-D'Croz, Daniel; Robinson, Sherman; Wiebe, Keith; Godfray, H Charles J; Rayner, Mike; Scarborough, Peter (7 November 2016). "Mitigation potential and global health impacts from emissions pricing of food commodities". Nature Climate Change (1): 69. S2CID 88921469.
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- ^ USDA. 2009. 2007 Census of agriculture. United States summary and State Data. Vol. 1. Geographic Area Series. Part 51. AC-07-A-51. 639 pp. + appendices.
- ^ USDA. 2009. 2007 Census of agriculture. Farm and ranch irrigation survey (2008). Volume 3. Special Studies. Part 1. AC-07-SS-1. 177 pp. + appendices.
- ^ Soyatech: http://soyatech.com/soy_facts.htm Archived 23 February 2012 at the Wayback Machine
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- ^ Elferink, E. V., S. Nonhebel and H. C. Moll. 2008. Feeding livestock food residue and the consequences for the environmental impact of meat. J. Cleaner Prod. 16: 1227-1233
- ^ Hoffman, L. and A. Baker. 2010. Market issues and prospects for U.S. distillers' grains supply, use, and price relationships. USDA FDS-10k-01).
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- Miguel Llanos, "Plastic bottles pile up as mountains of waste," (2005), MSNBC