Editing IPCC:AR6/WGI/Chapter-12 (section)

==== 12.3.5.3 Coastal Erosion ====

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Effective management of coastal ecosystems, cities, settlements, beaches and infrastructure requires information about coastal erosion driven by storm surge, waves and sea level rise ( [[#Dawson--2009|Dawson et al., 2009]] ; [[#Hinkel--2013|Hinkel et al., 2013]] ; [[#Harley--2017|Harley et al., 2017]] ; [[#Mentaschi--2017|Mentaschi et al., 2017]] ). Coastal erosion is generally accompanied by shoreline retreat, which can occur as a gradual process (e.g., due to sea level rise) or as an episodic event due to storm surge and/or extreme waves, especially when combined with high tide ( [[#Ranasinghe--2016|Ranasinghe, 2016]] ). The most commonly used shoreline retreat index is the magnitude of shoreline retreat by a pre-determined planning horizon such as 50 or 100 years into the future. Commonly used metrics for episodic coastal erosion include the beach erosion volume due to the 100-year recurrence storm wave height, the full exceedance probability distribution of coastal erosion volume ( [[#Li--2014a|Li et al., 2014a]] ; [[#Pender--2015|Pender et al., 2015]] ; [[#Ranasinghe--2017|Ranasinghe and Callaghan, 2017]] ) and the cumulative storm energy and storm power index ( [[#Godoi--2018|Godoi et al., 2018]] ). The destruction or overtopping of barrier islands may lead to irreversible changes in the physical system as well as in coastal ecosystems ( [[#Carrasco--2016|Carrasco et al., 2016]] ; [[#Zinnert--2019|Zinnert et al., 2019]] ). Shoreline position change rates along inlet-interrupted coasts may also be affected by changes in river flows and fluvial sediment supply ( [[#Hinkel--2013|Hinkel et al., 2013]] ; [[#Bamunawala--2018|Bamunawala et al., 2018]] ; [[#Ranasinghe--2019|Ranasinghe et al., 2019]] ). Permafrost thaw and Arctic sea ice decline also reduce natural coastal protection from wave erosion for communities and industry ( [[#Forbes--2011|Forbes, 2011]] ; [[#Melvin--2017|Melvin et al., 2017]] ).

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