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

=== 7.4.5 Demand-side Measures ===

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==== 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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==== 7.4.5.2 Reduce Food Loss and Waste ====

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'''Activities, co-benefits, risks and implementation opportunities and barriers.''' Food loss and waste (FLW) refer to the edible parts of plants and animals produced for human consumption that are not ultimately consumed ( [[#UNEP--2021b|UNEP 2021b]] ). Food loss occurs through spoilage, spilling or other unintended consequences due to limitations in agricultural infrastructure, storage and packaging ( [[#Parfitt--2010|Parfitt et al. 2010]] ). Food waste typically takes place at the distribution (retail and food service) and consumption stages in the food supply chain and refers to food appropriate for human consumption that is discarded or left to spoil ( [[#HLPE--2014|HLPE 2014]] ). Options that could reduce FLW include: investing in harvesting and post-harvesting technologies in developing countries, taxing and other incentives to reduce business and consumer-level waste in developed countries, mandatory FLW reporting and reduction targets for large food businesses, regulation of unfair trading practices, and active marketing of cosmetically imperfect products ( [[#van%20Giesen--2019|van Giesen and de Hooge 2019]] ; Sinclair [[#Taylor--2019|Taylor et al. 2019]] ). Other studies suggested providing options of longer-lasting products and behavioural changes (e.g., through information provision) that cause dietary and consumption changes and motivate consumers to actively make decisions that reduce FLW. Reductions of FLW along the food chain bring a range of benefits beyond GHG mitigation, including reducing environmental stress (e.g., water and land competition, land degradation, desertification), safeguarding food security, and reducing poverty ( [[#Galford--2020|Galford et al. 2020]] ; [[#Venkatramanan--2020|Venkatramanan et al. 2020]] ). Additionally, FLW reduction is crucial for achieving SDG 12 which calls for ensuring ‘sustainable consumption and production patterns’ through lowering per capita global food waste by 50% at the retail and consumer level and reducing food losses along food supply chains by 2030. In line with these SDG targets, it is estimated that reducing FLW can free up several million km 2 of land ( ''high confidence'' ). The interlinkages between reducing FLW and food system sustainability are discussed in Chapter 12. Recent literature identifies a range of barriers to climate change mitigation through FLW reduction, which are linked to technological, biophysical, socio-economic, financial and cultural contexts at regional and local levels ( [[#Vogel--2018|Vogel and Meyer 2018]] ; [[#Gromko--2019|Gromko and Abdurasalova 2019]] ; [[#Rogissart--2019|Rogissart et al. 2019]] ; [[#Blok--2020|Blok et al. 2020]] ). Examples of these barriers include infrastructural and capacity limitations, institutional regulations, financial resources, constraining resources (e.g., energy), information gaps (e.g., with retailers), and consumers’ behaviour ( [[#Gromko--2019|Gromko and Abdurasalova 2019]] ; [[#Blok--2020|Blok et al. 2020]] ).

'''Conclusions from AR5 and IPCC Special Reports (SR1.5, SROCC and SRCCL); mitigation potential, costs, and pathways.''' In AR5, reduced FLW was considered as a mitigation measure that could substantially lower emissions, with estimated mitigation potential of 0.6–6.0 GtCO 2 -eq yr –1 in the food supply chain (Smith et al. 2014). In the SRCCL, the technical mitigation potential of reducing food and agricultural waste was estimated at 0.76–4.5 GtCO 2 -eq yr –1 ( [[#Bajželj--2014|Bajželj et al. 2014]] ; [[#Dickie--2014b|Dickie et al. 2014b]] ; [[#Hawken--2017|Hawken 2017]] ) (SRCCL, [[IPCC:Wg3:Chapter:Chapter-2|Chapter 2]] and 6).

'''Developments since AR5 and IPCC Special Reports (SR1.5, SROCC and SRCCL).''' Since the SRCCL, there have been very few quantitative estimates of the mitigation potential of FLW reductions. Evidence suggests that reducing FLW together with overall food intake could have substantial mitigation potential, equating to an average of 0.3 tCO 2 -eq capita –1 ( [[#Ivanova--2020|Ivanova et al. 2020]] ). Some regional sectoral studies indicate that reducing FLW in the EU can reduce emissions by 186 MtCO 2 -eq yr –1 , the equivalent of around 15% of the environmental impacts (climate, acidification, and eutrophication) of the entire food value chain ( [[#Scherhaufer--2018|Scherhaufer et al. 2018]] ). In the UK, disruptive low-carbon innovations relating to FLW reduction were found to be associated with potential emissions reductions ranging between 2.6 and 3.6 MtCO 2 -eq ( [[#Wilson--2019|Wilson et al. 2019]] ). Other studies investigated the effect of tax mechanisms, such as ‘pay as you throw’ for household waste, on the mitigation potential of reducing FLW. Generally, these mechanisms are recognised as particularly effective in reducing the amount of waste and increasing the recycling rate of households ( [[#Carattini--2018|Carattini et al. 2018]] ; [[#Rogissart--2019|Rogissart et al. 2019]] ). Technological FWL mitigation opportunities exist throughout the food supply chain; post-harvest opportunities for FLW reductions are discussed in Chapter 12. Based on IPCC AR4 GWP100 values for CH 4 and N 2 O, greatest economic mitigation potential (up to USD100 tCO 2 –1 ) for the period 2020–2050 from FLW reduction is estimated to be in Asia and Pacific (192.3 GtCO 2 -eq yr –1 ) followed by Developed Countries (101.6 GtCO 2 -eq yr –1 ) ( [[#Roe--2021|Roe et al. 2021]] ). These estimates reflect diverted agricultural production and do not capture potential from avoided land-use changes.

'''Critical assessment and conclusion.''' There is ''medium confidence'' that reduced FLW has large global technical mitigation potential of 2.1 (0.1–5.8) GtCO 2 -eq yr –1 including savings in the full value chain and using GWP100 and a range of IPCC values for CH 4 and N 2 O. Potentials at 3.7 (2.2–5.1) GtCO 2 -eq yr –1 are considered plausible. When accounting for diverted agricultural production only, the feasible potential is 0.5 (0.0–0.9) GtCO 2 -eq yr –1 . See the section above for the joint land-use effects of food related demand-side measures which increases three-fold when accounting for the land-use effects as well. But this would overlap with other measures and is therefore not additive. Regionally, FLW reduction is feasible anywhere but its potential needs to be understood in a wider and changing socio-cultural context that determines nutrition ( ''hig'' ''h confidence'' ).

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==== 7.4.5.3 Improved and Enhanced Use of Wood Products ====

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'''Activities, co-benefits, risks and implementation opportunities and barriers.''' The use of wood products refers to the fate of harvested wood for material uses and includes two distinctly different components affecting the carbon cycle, including carbon storage in wood products and material substitution. When harvested wood is used for the manufacture of wood products, carbon remains stored in these products depending on their end use and lifetime. Carbon storage in wood products can be increased through enhancing the inflow of products in use, or effectively reducing the outflow of the products after use. This can be achieved through additional harvest under sustainable management ( [[#Pilli--2015|Pilli et al. 2015]] ; [[#Johnston--2019|Johnston and Radeloff 2019]] ), changing the allocation of harvested wood to long-lived wood products or by increasing products’ lifetime and increasing recycling ( [[#Brunet-Navarro--2017|Brunet-Navarro et al. 2017]] ; [[#Jasinevičius--2017|Jasinevičius et al. 2017]] ; [[#Xu--2018|Xu et al. 2018]] ; [[#Xie--2021|Xie et al. 2021]] ). Material substitution involves the use of wood for building, textiles, or other applications instead of other materials (e.g., concrete or steel, which consume more energy to produce) to avoid or reduce emissions associated with the production, use and disposal of those products it replaces.

The benefits and risks of improved and enhanced improved use of wood products are closely linked to forest management. First of all, the enhanced use of wood products could potentially activate or lead to improved sustainable forest management that can mitigate and adapt ( [[#Verkerk--2020|Verkerk et al. 2020]] ). Secondly, carbon storage in wood products and the potential for substitution effects can be increased by additional harvest, but with the risk of decreasing carbon storage in forest biomass when not done sustainably (P. [[#Smith--2019|Smith et al. 2019]] a). Conversely, reduced harvest may lead to gains in carbon storage in forest ecosystems locally, but these gains may be offset through international trade of forest products causing increased harvesting pressure or even degradation elsewhere ( [[#Kastner--2011|Kastner et al. 2011]] ; Kallio et al. 2018; [[#Pendrill--2019b|Pendrill et al. 2019b]] ). There are also environmental impacts associated with the processing, manufacturing, use and disposal of wood products ( [[#Adhikari--2018|Adhikari and Ozarska 2018]] ; [[#Baumgartner--2019|Baumgartner 2019]] ). See [[IPCC:Wg3:Chapter:Chapter-9#9.6.4|Section 9.6.4]] of this report for additional discussion on benefits and risks.

'''Conclusions from AR5 and IPCC Special Reports (SR1.5, SROCC and SRCCL); mitigation potential, costs, and pathways.''' There is strong evidence at the product level that wood products from sustainably managed forests are associated with less greenhouse emissions in their production, use and disposal over their life-time compared to products made from emission-intensive and non-renewable materials. However, there is still limited understanding of the substitution effects at the level of markets, countries ( [[#Leskinen--2018|Leskinen et al. 2018]] ). The AR5 did not report on the mitigation potential of wood products. The SRCCL (Chapters 2 and 6) finds that some studies indicate significant mitigation potentials for material substitution, but concludes that the global, technical mitigation potential for material substitution for construction applications ranges from 0.25–1 GtCO 2 -eq yr –1 ( ''medium confidence'' ) ( [[#Miner--2010|Miner 2010]] ; [[#McLaren--2012|McLaren 2012]] ; [[#Roe--2019|Roe et al. 2019]] ).

'''Developments since AR5 and IPCC Special Reports (SR1.5, SROCC and SRCCL).''' Since the SRCCL, several studies have examined the mitigation potential of the enhanced and improved use of wood products. A global forest sector modelling study ( [[#Johnston--2019|Johnston and Radeloff 2019]] ) estimated that carbon storage in wood products represented a net carbon stock increase of 0.34 GtCO 2 -eq yr –1 globally in 2015 and which could provide an average mitigation potential (by increasing the HWP pool) of 0.33–0.41 GtCO 2 -eq yr –1 for the period 2020–2050, based on the future socio-economic development (SSP scenarios) and its effect on the production and consumption of wood products. Traded feedstock provided another 0.071 GtCO 2 yr –1 of carbon storage in 2015 and 0.12 GtCO 2 yr –1 by 2065. These potentials exclude the effect of material substitution. Another recent study estimated the global mitigation potential of mid-rise urban buildings designed with engineered wood products at 0.04–3.7 GtCO 2 yr –1 ( [[#Churkina--2020|Churkina et al. 2020]] ). Another study ( [[#Oliver--2014|Oliver et al. 2014]] ) estimated that using wood to substitute for concrete and steel as building materials could provide a technical mitigation potential of 0.78–1.73 GtCO 2 yr –1 achieved through carbon storage in wood products and through material and energy substitution.

The limited availability or absence of estimates of the future mitigation potential of improved use of wood products for many world regions represents an important knowledge gap, especially with regards to material substitution effects. At the product level, wood products are often associated with lower fossil-based emissions from production, use and disposal, compared to products made from emission-intensive and non-renewable materials ( [[#Sathre--2010|Sathre and O’Connor 2010]] ; [[#Geng--2017|Geng et al. 2017]] ; [[#Leskinen--2018|Leskinen et al. 2018]] ).

'''Critical assessment and conclusion.''' Based on studies to date, there is ''strong evidence'' and ''medium agreement'' that the improved use of wood products has a technical potential of 1.0 (0.04–3.7) GtCO 2 -eq yr –1 and economic potential of 0.4 (0.3–0.5) GtCO 2 -eq yr –1 . There is ''strong evidence'' and ''high agreement'' at the product level that material substitution provides on average benefits for climate change mitigation as wood products are associated with less fossil-based GHG emissions over their lifetime compared to products made from emission-intensive and non-renewable materials. However, the evidence at the level of markets or countries is uncertain and fairly limited for many parts of the world. There is ''medium confidence'' that material substitution and carbon storage in wood products contribute to climate change mitigation when also the carbon balances of forest ecosystems are considered of sustainably managed large areas of forests in medium term. The total future mitigation potential will depend on the forest system considered, the type of wood products that are produced and substituted and the assumed production technologies and conversion efficiencies of these products.

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