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

==== 3.4.5.6 Other coastal settings ====

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Numerous impacts have not been quantified at 1.5°C or 2°C but remain important. This includes systems identified in WGII AR5 (AR5 – Section 5.4 of Wong et al., 2014) <sup>[[#fn:r804|804]]</sup> , such as beaches, barriers, sand dunes, rocky coasts, aquifers, lagoons and coastal ecosystems (for the last system, see Section 3.4.4.12). For example, SLR potentially affects erosion and accretion, and therefore sediment movement, instigating shoreline change (Section 5.4.2.1 of Wong et al., 2014) <sup>[[#fn:r805|805]]</sup> , which could affect land-based ecosystems. Global observations indicate no overall clear effect of SLR on shoreline change (Le Cozannet et al., 2014) <sup>[[#fn:r806|806]]</sup> , as it is highly site specific (e.g., Romine et al., 2013) <sup>[[#fn:r807|807]]</sup> . Infrastructure and geological constraints reduce shoreline movement, causing coastal squeeze. In Japan, for example, SLR is projected to cause beach losses under an RCP2.6 scenario, which will worsen under RCP8.5 (Udo and Takeda, 2017) <sup>[[#fn:r808|808]]</sup> . Further, compound flooding (the combined risk of flooding from multiple sources) has increased significantly over the past century in major coastal cities (Wahl et al., 2015) <sup>[[#fn:r809|809]]</sup> and is ''likely'' to increase with further development and SLR at 1.5°C and 2°C unless adaptation is undertaken. Thus, overall SLR will have a wide range of adverse effects on coastal zones (medium confidence).

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