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

==== 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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