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

==== 12.3.5.1 Relative Sea Level ====

<div id="h3-23-siblings" class="h3-siblings"></div>

Sea level rise hazards for coastal ecosystems, infrastructure, farmland, cities and settlements in a particular region are often driven by regional changes in relative sea level (RSL) that account for land uplift or subsidence and thus represent local asset vulnerability better than global mean sea level (Box 9.1; [[#Hallegatte--2013|Hallegatte et al., 2013]] ; [[#Hinkel--2013|Hinkel et al., 2013]] ; [[#McInnes--2016|McInnes et al., 2016]] ; [[#Weatherdon--2016|Weatherdon et al., 2016]] ; [[#Brown--2018|Brown et al., 2018]] ; [[#IPCC--2019b|IPCC, 2019b]] ; [[#Rasoulkhani--2020|Rasoulkhani et al., 2020]] ). Vertical land motion (i.e., land subsidence) caused by local fluid (gas or groundwater) extraction can also have a large influence on relative sea levels ( [[#Minderhoud--2020|Minderhoud et al., 2020]] ). Several indices have been suggested to signify coastal inundation, including a threshold when the local land elevation falls below the local mean higher high water (MHHW) that is close to the ‘high tide’ level ( [[#Kulp--2019|Kulp and Strauss, 2019]] ) or a threshold when flooding occurs about once every two weeks ( [[#Sweet--2014|Sweet and Park, 2014]] ; [[#Dahl--2017b|Dahl et al., 2017b]] ). RSL rise (or RSLR) can drive increased inland penetration of above-ground and subterranean salt water fronts (i.e., salinity intrusion) affecting coastal ecosystems, agriculture and water resources ( [[#Ferguson--2012|Ferguson and Gleeson, 2012]] ; [[#Kirwan--2013|Kirwan and Megonigal, 2013]] ; [[#Rotzoll--2013|Rotzoll and Fletcher, 2013]] ; [[#Chen--2016|Chen et al., 2016]] ; [[#Colombani--2016|Colombani et al., 2016]] ; [[#Holding--2016|Holding et al., 2016]] ; [[#Sawyer--2016|Sawyer et al., 2016]] ; [[#Mohammed--2018|Mohammed and Scholz, 2018]] ). The rate of RSLR can determine the survival and net pressure on niche coastal ecosystems such as mangroves, tidal flats, sea grasses and coral reefs ( [[#Hubbard--2008|Hubbard et al., 2008]] ; [[#Craft--2009|Craft et al., 2009]] ; [[#Bell--2013|Bell et al., 2013]] ; [[#Kirwan--2013|Kirwan and Megonigal, 2013]] ; [[#Alongi--2015|Alongi, 2015]] ; [[#Ellison--2015|Ellison, 2015]] ; [[#Lovelock--2015|Lovelock et al., 2015]] ; [[#Ward--2016|Ward et al., 2016]] ; [[#Lee--2018|Lee et al., 2018]] ).

<div id="12.3.5.2" class="h3-container"></div>

<span id="coastal-flood"></span>