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

==== 7.4.2.6 Reduce Degradation and Conversion of Peatlands Activities, Co-benefits, Risks and Implementation Barriers ====

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Peatlands are carbon-rich wetland ecosystems with organic soil horizons in which soil organic matter concentration exceeds 30% (dry weight) and soil carbon concentrations can exceed 50% ( [[#Page--2016|Page and Baird 2016]] , [[#Boone%20Kauffman--2017|Boone Kauffman et al. 2017]] ). Reducing the conversion of peatlands avoids emissions of above- and below-ground biomass and soil carbon due to vegetation clearing, fires, and peat decomposition from drainage. Similar to deforestation, peatland carbon stocks can be conserved by controlling the drivers of conversion and degradation (e.g., commercial and subsistence agriculture, mining, urban expansion) and improving governance and management. Reducing conversion is urgent because peatland carbon stocks accumulate slowly and persist over millennia; loss of existing stocks cannot be easily reversed over the decadal time scales needed to meet the Paris Agreement ( [[#Goldstein--2020|Goldstein et al. 2020]] ). The main co-benefits of reducing conversion of peatlands include conservation of a unique biodiversity including many critically endangered species, provision of water quality and regulation, and improved public health through decreased fire-caused pollutants ( [[#Griscom--2017|Griscom et al. 2017]] ). Although reducing peatland conversion will reduce land availability for alternative uses including agriculture or other land-based mitigation, drained peatlands constitute a small share of agricultural land globally while contributing significant emissions ( [[#Joosten--2009|Joosten 2009]] ). Mitigation through reduced conversion of peatlands therefore has a high potential of avoided emissions per hectare ( [[#Roe--2019|Roe et al. 2019]] ).

'''Conclusions from AR5 and IPCC Special Reports (SR1.5, SROCC and SRCCL); mitigation potential, costs, and pathways.''' In the SRCCL (Chapters 2 and 6), it was estimated that avoided peat impacts could deliver 0.45–1.22 GtCO 2 -eq yr –1 technical potential by 2030–2050 ( ''medium confidence'' ) ( [[#Hooijer--2010|Hooijer et al. 2010]] ; [[#Griscom--2017|Griscom et al. 2017]] ; [[#Hawken--2017|Hawken 2017]] ). The mitigation potential estimates cover tropical peatlands and include CO 2 , N 2 O and CH 4 emissions. The mitigation potential is derived from quantification of losses of carbon stocks due to land conversion, shifts in GHG fluxes, alterations in net ecosystem productivity, input factors such as fertilisation needs, and biophysical climate impacts (e.g., shifts in albedo, water cycles, etc.). Tropical peatlands account for only about 10% of peatland area and about 20% of peatland carbon stock but about 80% of peatland carbon emissions, primarily from peatland conversion in Indonesia (about 60%) and Malaysia (about 10%) ( [[#Hooijer--2010|Hooijer et al. 2010]] ; [[#Page--2011|Page et al. 2011]] ; [[#Leifeld--2018|Leifeld and Menichetti 2018]] ). While the total mitigation potential of peatland conservation is considered moderate, the per hectare mitigation potential is the highest among land-based mitigation measures ( [[#Roe--2019|Roe et al. 2019]] ).

'''Developments since AR5 and IPCC Special Reports (SR1.5, SROCC and SRCCL).''' Recent studies continue to report high carbon stocks in peatlands and emphasise the vulnerability of peatland carbon after conversion. The carbon stocks of tropical peatlands are among the highest of any forest, 1,211–4,257 tCO 2 -eq ha –1 in the Peruvian Amazon ( [[#Bhomia--2019|Bhomia et al. 2019]] ) and 1,956–14,757 tCO 2 -eq ha –1 in Indonesia ( [[#Novita--2021|Novita et al. 2021]] ). Ninety percent of tropical peatland carbon stocks are vulnerable to emission during conversion and may not be recoverable through restoration; in contrast, boreal and temperate peatlands hold similar carbon stocks (1,439–5,619 tCO 2 -eq ha –1 ) but only 30% of northern carbon stocks are vulnerable to emission during conversion and irrecoverable through restoration ( [[#Goldstein--2020|Goldstein et al. 2020]] ). A recent study shows global mitigation potential of about 0.2 GtCO 2 -eq yr –1 at costs up to USD100 tCO 2 –1 ( [[#Roe--2021|Roe et al. 2021]] ). Another study estimated that 72% of mitigation is achieved through avoided soil carbon impacts, with the remainder through avoided impacts to vegetation ( [[#Bossio--2020|Bossio et al. 2020]] ). Recent model projections show that both peatland protection and peatland restoration ( [[#7.4.2.7|Section 7.4.2.7]] ) are needed to achieve a 2°C mitigation pathway and that peatland protection and restoration policies will have minimal impacts on regional food security ( [[#Leifeld--2019|Leifeld et al. 2019]] , [[#Humpenöder--2020|Humpenöder et al. 2020]] ). Global studies have not accounted for extensive peatlands recently reported in the Congo Basin, estimated to cover 145,500 km 2 and contain 30.6 PgC, as much as 29% of total tropical peat carbon stock ( [[#Dargie--2017|Dargie et al. 2017]] ). These Congo peatlands are relatively intact; continued preservation is needed to prevent major emissions ( [[#Dargie--2019|Dargie et al. 2019]] ). In northern peatlands that are underlain by permafrost roughly 50% of the total peatlands north of 23° latitude, ( [[#Hugelius--2020|Hugelius et al. 2020]] ), climate change (i.e., warming) is the major driver of peatland degradation (e.g., through permafrost thaw) ( [[#Schuur--2015|Schuur et al. 2015]] , [[#Goldstein--2020|Goldstein et al. 2020]] ). However, in non-permafrost boreal and temperate peatlands, reduction of peatland conversion is also a cost-effective mitigation strategy. Peatlands are sensitive to climate change and there is ''low confidence'' about the future peatland sink globally (SRCCL, Chapter 2). Permafrost thaw may shift northern peatlands from a net carbon sink to net source ( [[#Hugelius--2020|Hugelius et al. 2020]] ). Uncertainties in peatland extent and the magnitude of existing carbon stocks, in both northern ( [[#Loisel--2014|Loisel et al. 2014]] ) and tropical ( [[#Dargie--2017|Dargie et al. 2017]] ) latitudes limit understanding of current and future peatland carbon dynamics ( [[#Minasny--2019|Minasny et al. 2019]] ).

'''Critical assessment and conclusion.''' Based on studies to date, there is ''medium confidence'' that peatland conservation has a technical potential of 0.86 (0.43–2.02) GtCO 2 -eq yr –1 of which 0.48 (0.2–0.68) GtCO 2 -eq yr –1 is available at USD100 tCO 2 –1 (Figure 7.11). High per hectare mitigation potential and high rate of co-benefits particularly in tropical countries, support the effectiveness of this mitigation strategy ( [[#Roe--2019|Roe et al. 2019]] ). Feasibility of reducing peatland conversion may depend on countries’ governance, financial capacity and political will.

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