Editing IPCC:AR6/WGII/Cross-Chapter-Paper-4 (section)

=== CCP4.3.2 Coastal Systems ===

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Sea level rise is the origin of multiple risks for low-lying areas in the Mediterranean Basin; for example, the further increase in flooding at high tide in some locations, such as Venice ( ''high confidence'' ) (Chapter 13; [[#Cid--2016|Cid et al., 2016]] ; [[#Pomaro--2017|Pomaro et al., 2017]] ). Currently, 37% of coastal areas are at moderate to high risk from coastal erosion and flooding ( [[#Satta--2017|Satta et al., 2017]] ). Due to rapid urban development, many coastal assets are directly exposed to projected sea level rise and coastal hazards, with limited adaptation options and resilience of beaches (Section CCP4.2; [[#Brown--2016|Brown et al., 2016]] ; [[#Jiménez--2017|Jiménez et al., 2017]] ).

The Mediterranean is a micro-tidal sea, where storms may hit the coast over several hours or longer, and not only during high tides ( [[#Le%20Cozannet--2015|Le Cozannet et al., 2015]] ; [[#Sánchez-Arcilla--2016|Sánchez-Arcilla et al., 2016]] ; [[#Sierra--2016|Sierra et al., 2016]] ; [[#Sayol--2018|Sayol and Marcos, 2018]] ). Projected changes of winds, storms and waves are small, and confidence in these changes is limited by the quality of climate models applied to the Mediterranean ( [[#Calafat--2014|Calafat et al., 2014]] ; [[#Androulidakis--2015|Androulidakis et al., 2015]] ; [[#Vousdoukas--2017|Vousdoukas et al., 2017]] ). Overall, sea level rise is projected to increase the risk of coastal flooding despite the potential slight reductions of marine storms ( ''high confidence'' ) ( [[#Lionello--2017|Lionello et al., 2017]] ; [[#Vousdoukas--2017|Vousdoukas et al., 2017]] ). Risks of erosion and flooding will be amplified with climate change, particularly in river deltas (Figure CCP4.6; [[#Ali--2016|Ali and El-Magd, 2016]] ), on low-lying floodplains, on sandy beaches around the basin and in many coastal cities ( [[#Satta--2017|Satta et al., 2017]] ). Impacts are projected to increase nonlinearly during the 21st century with higher sea level rise, because coastal flooding will progressively change from overtopping to overflow, high-tide flooding and ultimately permanent flooding and shoreline retreat ( ''high confidence'' ) ( [[#Le%20Cozannet--2015|Le Cozannet et al., 2015]] ; [[#Sánchez-Arcilla--2016|Sánchez-Arcilla et al., 2016]] ; [[#Sierra--2016|Sierra et al., 2016]] ; [[#Antonioli--2017|Antonioli et al., 2017]] ; [[#Anzidei--2017|Anzidei et al., 2017]] ; [[#Ciro%20Aucelli--2017|Ciro Aucelli et al., 2017]] ; [[#Enríquez--2017|Enríquez et al., 2017]] ; [[#Jiménez--2017|Jiménez et al., 2017]] ; [[#Sayol--2018|Sayol and Marcos, 2018]] ). These risks may be amplified further in areas with poor storm water management and sealed urban surfaces ( [[#Llasat--2013|Llasat et al., 2013]] ; [[#Gaume--2016|Gaume et al., 2016]] ).

Combined with storm surges, sea level rise may disrupt Mediterranean port operations ( [[#Sánchez-Arcilla--2016|Sánchez-Arcilla et al., 2016]] ; [[#Sierra--2016|Sierra et al., 2016]] ), with risks depending on adaptation, physical protection measures and basin depth. Risks for deep ports are more limited ( [[#Sierra--2017|Sierra et al., 2017]] ), while low-depth small harbours, common in the Mediterranean, could be significantly affected ( [[#Sierra--2016|Sierra et al., 2016]] ). Sea level rise may enhance sandy beach erosion and thereby impact recreation and tourism ( [[#Bitan--2018|Bitan and Zviely, 2018]] ; [[#Rizzetto--2020|Rizzetto, 2020]] ), magnifying coastal degradation and pollution ( [[#Enríquez--2017|Enríquez et al., 2017]] ; [[#Gössling--2018|Gössling et al., 2018]] ).

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