Editing IPCC:AR6/SR15/Chapter-3 (section)

==== 3.4.4.8 Sea level rise ====

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Mean sea level is increasing (Section 3.3.9), with substantial impacts already being felt by coastal ecosystems and communities (Wong et al., 2014) <sup>[[#fn:r631|631]]</sup> ( ''high confidence'' ). These changes are interacting with other factors, such as strengthening storms, which together are driving larger storm surges, infrastructure damage, erosion and habitat loss (Church et al., 2013; Stocker et al., 2013; Blankespoor et al., 2014) <sup>[[#fn:r632|632]]</sup> . Coastal wetland ecosystems such as mangroves, sea grasses and salt marshes are under pressure from rising sea level ( ''medium confidence'' ) (Section 3.4.5; Di Nitto et al., 2014; Ellison, 2014; Lovelock et al., 2015; Mills et al., 2016; Nicholls et al., 2018) <sup>[[#fn:r633|633]]</sup> , as well as from a wide range of other risks and impacts unrelated to climate change, with the ongoing loss of wetlands recently estimated at approximately 1% per annum across a large number of countries (Blankespoor et al., 2014; Alongi, 2015) <sup>[[#fn:r634|634]]</sup> . While some ecosystems (e.g., mangroves) may be able to shift shoreward as sea levels increase, coastal development (e.g., buildings, seawalls and agriculture) often interrupts shoreward shifts, as well as reducing sediment supplies down some rivers (e.g., dams) due to coastal development (Di Nitto et al., 2014; Lovelock et al., 2015; Mills et al., 2016) <sup>[[#fn:r635|635]]</sup> .

Responses to sea level rise challenges for ocean and coastal systems include reducing the impact of other stresses, such as those arising from tourism, fishing, coastal development, reduced sediment supply and unsustainable aquaculture/agriculture, in order to build ecological resilience (Hossain et al., 2015; Sutton-Grier and Moore, 2016; Asiedu et al., 2017a) <sup>[[#fn:r636|636]]</sup> . The available literature largely concludes that these impacts will intensify under a 1.5°C warmer world but will be even higher at 2°C, especially when considered in the context of changes occurring beyond the end of the current century. In some cases, restoration of coastal habitats and ecosystems may be a cost-effective way of responding to changes arising from increasing levels of exposure to rising sea levels, intensifying storms, coastal inundation and salinization (Section 3.4.5 and Box 3.5; Arkema et al., 2013) <sup>[[#fn:r637|637]]</sup> , although limitations of these strategies have been identified (e.g., Lovelock et al., 2015; Weatherdon et al., 2016) <sup>[[#fn:r638|638]]</sup> .

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