Editing IPCC:AR6/WGIII/Chapter-7 (section)

==== 7.4.5.1 Shift to Sustainable Healthy Diets ====

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'''Activities, co-benefits, risks and implementation opportunities and barriers.''' The term ‘sustainable healthy diets’ refers to dietary patterns that ‘promote all dimensions of individuals’ health and well-being; have low environmental pressure and impact; are accessible, affordable, safe and equitable; and are culturally acceptable’ ( [[#FAO%20and%20WHO--2019|FAO and WHO 2019]] ). In addition to climate mitigation gains, a transition towards more plant-based consumption and reduced consumption of animal-based foods, particularly from ruminant animals, could reduce pressure on forests and land used for feed, support the preservation of biodiversity and planetary health ( [[#FAO--2018c|FAO 2018c]] ; [[#Theurl--2020|Theurl et al. 2020]] ), and contribute to preventing forms of malnutrition (i.e., undernutrition, micronutrient deficiency, and obesity) in developing countries ( [[IPCC:Wg3:Chapter:Chapter-12#12.4|Section 12.4]] ). Other co-benefits include lowering the risk of cardiovascular disease, type 2 diabetes, and reducing mortality from diet-related non-communicable diseases ( [[#Toumpanakis--2018|Toumpanakis et al. 2018]] ; [[#Satija--2018|Satija and Hu 2018]] ; [[#Faber--2020|Faber et al. 2020]] ; [[#Magkos--2020|Magkos et al. 2020]] ). However, transition towards sustainable healthy diets could have adverse impacts on the economic stability of the agricultural sector (MacDiarmid 2013; [[#Aschemann-Witzel--2015|Aschemann-Witzel 2015]] ; [[#Van%20Loo--2017|Van Loo et al. 2017]] ). Therefore, shifting toward sustainable and healthy diets requires effective food-system oriented reform policies that integrate agriculture, health, and environment policies to comprehensively address synergies and conflicts in co-lateral sectors (agriculture, trade, health, environment protection etc.) and capture spill-over effects, for example, climate change, biodiversity loss, food poverty ( [[#FAO%20and%20WHO--2019|FAO and WHO 2019]] ; [[#Galli--2020|Galli et al. 2020]] ).

'''Conclusions from AR5 and IPCC Special Reports (SR1.5, SROCC and SRCCL); mitigation potential, costs, and pathways.''' According to the AR5, changes in human diets and consumption patterns can reduce emissions 5.3 to 20.2 GtCO 2 -eq yr –1 by 2050 from diverted agricultural production and avoided land-use change (Smith et al. 2014). In the SRCCL, a ‘contract and converge’ model of transition to sustainable healthy diets was suggested as an effective approach, reducing food consumption in over-consuming populations and increasing consumption of some food groups in populations where minimum nutritional needs are not met (P. [[#Smith--2019|Smith et al. 2019]] a). The total technical mitigation potential of changes in human diets was estimated as 0.7–8 GtCO 2 -eq yr –1 by 2050 ( [[#Tilman--2014|Tilman and Clark 2014]] ; [[#Springmann--2016|Springmann et al. 2016]] ; [[#Hawken--2017|Hawken 2017]] ) (SRCCL, [[IPCC:Wg3:Chapter:Chapter-2|Chapter 2]] and 6), ranging from a 50% adoption of healthy diets (&lt;60g of animal-based protein) and only accounting for diverted agricultural production, to the global adoption of a vegetarian diet.

'''Developments since AR5 and IPCC Special Reports (SR1.5, SROCC and SRCCL).''' Since the SRCCL, global studies continue to find high mitigation potential from reducing animal-source foods and increasing proportions of plant-rich foods in diets. [[#Springmann--2018|Springmann et al. (2018)]] estimated that diet changes in line with global dietary guidelines for total energy intake and consumption of red meat, sugar, fruits, and vegetables, could reduce GHG emissions by 29% and other environmental impacts by 5–9% compared with the baseline in 2050. [[#Poore--2018|Poore and Nemecek (2018)]] revealed that shifting towards diets that exclude animal-source food could reduce land use by 3.1 billion ha, decrease food-related GHG emissions by 6.5 GtCO 2 -eq yr –1 , acidification by 50%, eutrophication by 49%, and freshwater withdrawals by 19% for a 2010 reference year. [[#Frank--2019|Frank et al. (2019)]] estimated non-CO 2 emissions reductions of 0.4 GtCO 2 -eq yr –1 at a carbon price of USD100 tCO 2 –1 and 0.6 GtCO 2 -eq yr –1 at USD20 tCO 2 –1 in 2050 from shifting to lower animal-source diets (430 kcal of livestock calorie intake) in developed and emerging countries. From a systematic literature review, [[#Ivanova--2020|Ivanova et al. (2020)]] found mitigation potentials of 0.4–2.1 tCO 2 -eq capita –1 for a vegan diet, of 0.01–1.5 for a vegetarian diet, and of 0.1–2.0 for Mediterranean or similar healthy diet.

Regionally, mitigation potentials for shifting towards sustainable healthy diets (50% convergence to &lt;60g of meat-based protein, only accounting for diverted production) vary across regions. A recent assessment finds greatest economic (up to USD100 tCO 2 –1 ) potential for 2020–2050 in Asia and the Pacific (609 MtCO 2 -eq yr –1 ) followed by Developed Countries (322 MtCO 2 -eq yr –1 ) based on IPCC AR4 GWP100 values for CH 4 and N 2 O) ( [[#Roe--2021|Roe et al. 2021]] ). In the EU, ( [[#Latka--2021|Latka et al. 2021]] ) found that moving to healthy diets through price incentives could bring about annual reductions of non-CO 2 emissions from agriculture of 12–111 MtCO 2 -eq yr –1 . At the country level, recent studies show that following National Dietary Guidelines (NDG) would reduce food system GHG emissions by 4–42%, confer large health gains (1.0–1.5 million quality-adjusted life-years) and lower health care system costs (NZD 14–20 billion) in New Zealand [[#Drew--2020|Drew et al. (2020)]] ; reduce 28% of GHG emissions in Argentina [[#Arrieta--2018|Arrieta and González (2018)]] ; about 25% in Portugal [[#Esteve-Llorens--2020|Esteve-Llorens et al. (2020)]] and reduce GHG emissions, land use and blue water footprint by 15–60% in Spain ( [[#Batlle-Bayer--2020|Batlle-Bayer et al. 2020]] ). In contrast, [[#Aleksandrowicz--2019|Aleksandrowicz et al. (2019)]] found that meeting healthy dietary guidelines in India required increased dietary energy intake overall, which slightly increased environmental footprints by about 3–5% across GHG emissions, blue and green water footprints and land use.

'''Critical assessment and conclusion''' ''.'' Shifting to sustainable healthy diets has large potential to achieve global GHG mitigation targets as well as public health and environmental benefits ( ''high confidence'' ). Based on studies to date, there is ''medium confidence'' that shifting toward sustainable healthy diets has a technical potential including savings in the full value chain of 3.6 (0.3–8.0) GtCO 2 -eq yr –1 of which 2.5 (1.5–3.9) GtCO 2 -eq yr –1 is considered plausible based on a range of GWP100 values for CH 4 and N 2 O. When accounting for diverted agricultural production only, the feasible potential is 1.7 (1–2.7) GtCO 2 -eq yr –1 . A shift to more sustainable and healthy diets is generally feasible in many regions ( ''medium confidence'' ). However, potential varies across regions as diets are location- and community- specific, and thus may be influenced by local production practices, technical and financial barriers and associated livelihoods, everyday life and behavioural and cultural norms around food consumption ( [[#Meybeck--2017|Meybeck and Gitz 2017]] ; [[#Creutzig--2018|Creutzig et al. 2018]] ; [[#FAO--2018b|FAO 2018b]] ). Therefore, a transition towards low-GHG emission diets and achieving their mitigation potential requires a combination of appropriate policies, financial and non-financial incentives and awareness-raising campaigns to induce changes in consumer behaviour with potential synergies between climate objectives, health and equity ( [[#Rust--2020|Rust et al. 2020]] ).

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