Editing IPCC:AR6/SRCCL/Chapter-2 (section)

==== 2.6.1.4 Land management in other ecosystems ====

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Protection and restoration of wetlands, peatlands and coastal habitats reduces net carbon loss (primarily from sediment/soils) and provides continued or enhanced natural CO2 removal (Section 4.9.4). Reducing annual emissions from peatland conversion, draining and burning could mitigate 0.45–1.22 GtCO2-eq yr–1 up to 2050 (medium confidence) (Hooijer et al. 2010 <sup>[[#fn:r1732|1732]]</sup> ; Griscom et al. 2017 <sup>[[#fn:r1733|1733]]</sup> ; Hawken 2017 <sup>[[#fn:r1734|1734]]</sup> ) and peatland restoration 0.15–0.81 (low confidence) (Couwenberg et al. 2010 <sup>[[#fn:r1735|1735]]</sup> ; Griscom et al. 2017 <sup>[[#fn:r1736|1736]]</sup> ). The upper end from Griscom et al. (2017) <sup>[[#fn:r1737|1737]]</sup> represents a maximum sustainable potential (accounting for biodiversity and food security safeguards) for rewetting and biomass enhancement. Wetland drainage and rewetting was included as a flux category under the second commitment period of the Kyoto Protocol, with significant management knowledge gained over the last decade (IPCC 2013b). However, there are high uncertainties as to carbon storage and flux rates, in particular the balance between CH4 sources and CO2 sinks (Spencer et al. 2016 <sup>[[#fn:r1738|1738]]</sup> ). Peatlands are sensitive to climate change which may increase carbon uptake by vegetation and carbon emissions due to respiration, with the balance being regionally dependent (high confidence). There is low confidence about the future peatland sink globally. Some peatlands have been found to be resilient to climate change (Minayeva and Sirin 2012 <sup>[[#fn:r1739|1739]]</sup> ), but the combination of land use change and climate change may make them vulnerable to fire (Sirin et al. 2011 <sup>[[#fn:r1740|1740]]</sup> ). While models show mixed results for the future sink (Spahni et al. 2013 <sup>[[#fn:r1741|1741]]</sup> ; Chaudhary et al. 2017 <sup>[[#fn:r1742|1742]]</sup> ; Ise et al. 2008 <sup>[[#fn:r1743|1743]]</sup> ), a study that used extensive historical data sets to project change under future warming scenarios found that the current global peatland sink could increase slightly until 2100 and decline thereafter (Gallego-Sala et al. 2018 <sup>[[#fn:r1744|1744]]</sup> ).

Reducing the conversion of coastal wetlands (mangroves, seagrass and marshes) could reduce emissions by 0.11–2.25 GtCO2-eq yr–1 by 2050 (medium confidence) (Pendleton et al. 2012 <sup>[[#fn:r1745|1745]]</sup> ; Griscom et al. 2017 <sup>[[#fn:r1746|1746]]</sup> ; Howard et al. 2017 <sup>[[#fn:r1747|1747]]</sup> ; Hawken 2017 <sup>[[#fn:r1748|1748]]</sup> ). Mangrove restoration can mitigate the release of 0.07 GtCO2 yr–1 through rewetting (Crooks et al. 2011 <sup>[[#fn:r1749|1749]]</sup> ) and take up 0.02–0.84 GtCO2 yr–1 from biomass and soil enhancement (medium confidence) (Griscom et al. 2017 <sup>[[#fn:r1750|1750]]</sup> ). The ongoing benefits provided by mangroves as a natural carbon sink can be nationally-important for small island developing states (SIDS) and other countries with extensive coastlines, based on estimates of high carbon sequestration rates per unit area (McLeod et al. 2011 <sup>[[#fn:r1751|1751]]</sup> ; Duarte et al. 2013 <sup>[[#fn:r1752|1752]]</sup> ; Duarte 2017 <sup>[[#fn:r1753|1753]]</sup> ; Taillardat et al. 2018 <sup>[[#fn:r1754|1754]]</sup> ). There is only medium confidence in the effectiveness of enhanced carbon uptake using mangroves, due to the many uncertainties regarding the response of mangroves to future climate change (Jennerjahn et al. 2017 <sup>[[#fn:r1755|1755]]</sup> ), dynamic changes in distributions (Kelleway et al. 2017 <sup>[[#fn:r1756|1756]]</sup> ) and other local-scale factors affecting long-term sequestration and climatic benefits (e.g., methane release) (Dutta et al. 2017 <sup>[[#fn:r1757|1757]]</sup> ). The climate mitigation potential of coastal vegetated habitats (mangrove forests, tidal marshes and seagrasses) is considered in Chapter 5 of the IPCC Special Report on the Ocean, Cryosphere and Climate Change (SROCC), in a wider ‘blue carbon’ context.

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