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

== CCP4.3 Projected Climate Risks in the Mediterranean Basin ==

<div id="CCP4.3.1" class="h2-container"></div>

<span id="ccp4.3.1-ocean-systems"></span>
=== CCP4.3.1 Ocean Systems ===

<div id="h2-8-siblings" class="h2-siblings"></div>

With warming, marine primary production is projected to decrease in the western and increase in the eastern Mediterranean Sea ( [[#Macias--2015|Macias et al., 2015]] ). The diversity of copepods (species which dominate the meso-zooplankton communities feeding Mediterranean fishes) is projected to decline over most of the Mediterranean, albeit with regional variation ( [[#Benedetti--2018|Benedetti et al., 2018]] ). Total marine biomass (and fishery potential) is projected to increase in the southeastern Mediterranean, whereas significant decreases are most likely in the west ( [[#Moullec--2019|Moullec et al., 2019]] ). The projected increase of marine heat waves in the Mediterranean Sea will add additional pressures to coastal and marine ecosystems. Warm-water fish species are expected to move northwards, while cold-water species will decline, and invasions of thermal-tolerant tropical species will increase ( ''high confidence'' ) ( [[#Lloret--2015|Lloret et al., 2015]] ; [[#Corrales--2018|Corrales et al., 2018]] ). Fish species richness is predicted to increase in the eastern and decrease in the western Mediterranean by 2050 but, by 2100, the cooler areas in the north will become a ‘cul-de-sac’ for many species ( [[#Albouy--2013|Albouy et al., 2013]] ; [[#Burrows--2014|Burrows et al., 2014]] ). Out of 75 endemic fish species, 14 are projected to go extinct, almost all of them benthic and demersal species ( [[#Ben%20Rais%20Lasram--2010|Ben Rais Lasram et al., 2010]] ). The abundance of small and medium-sized pelagic fish (e.g., European anchovy) is projected to decline by 15–33% by 2100 ( [[#Stergiou--2016|Stergiou et al., 2016]] ; [[#Raybaud--2017|Raybaud et al., 2017]] ).

Heat waves will ''likely'' cause increasing mass mortality events of benthic species, mostly invertebrate organisms, such as corals, sponges, bivalves, ascidians and bryozoans, increasing the risks of abrupt collapse of endemic species ( [[#Kersting--2013|Kersting et al., 2013]] ; [[#Rivetti--2014|Rivetti et al., 2014]] ; [[#Rivetti--2017|Rivetti et al., 2017]] ; [[#Garrabou--2019|Garrabou et al., 2019]] ; [[#Garrabou--2021|Garrabou et al., 2021]] ). Deep-water corals live near their upper thermal tolerance and further warming could thus reduce their biotic potential and long-term survival ( [[#Nannini--2015|Nannini et al., 2015]] ; [[#Yasuhara--2016|Yasuhara and Danovaro, 2016]] ; [[#Marchini--2019|Marchini et al., 2019]] ), although there are some exceptions ( [[#Naumann--2013|Naumann et al., 2013]] ) and also knowledge gaps ( [[#Maier--2019|Maier et al., 2019]] ). Warming has been shown to severely reduce the metabolism of some Mediterranean coral species ( [[#Gori--2016|Gori et al., 2016]] ). In summary, the observed shift in marine ecosystems since 1980 is projected to continue and intensify, resulting in very high risks for marine ecosystems between 1.5°C–2°C global warming levels (GWL) (Figure CCP4.8; Chapters 3; 13; CCP1; [[#Manes--2021|Manes et al., 2021]] ).

<div id="CCP4.3.2" class="h2-container"></div>

<span id="ccp4.3.2-coastal-systems"></span>
=== CCP4.3.2 Coastal Systems ===

<div id="h2-9-siblings" class="h2-siblings"></div>

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]] ).

<div id="CCP4.3.3" class="h2-container"></div>

<span id="ccp4.3.3-inland-ecosystems"></span>
=== CCP4.3.3 Inland Ecosystems ===

<div id="h2-10-siblings" class="h2-siblings"></div>

Beyond 3°C GWL, 13–30% of the Mediterranean Natura 2000 protected area and 15–23% of Natura 2000 sites are projected to change towards more arid ecosystem types ( [[#Barredo--2016|Barredo et al., 2016]] ). Biodiversity and ecosystem services would be exposed to degradation of wetland hydrology, which could affect 19–32% of localities under a 1.5°C–2°C GWL (48–73% under higher warming), particularly in Spain, Portugal, Morocco and Algeria ( [[#Lefebvre--2019|Lefebvre et al., 2019]] ). There is also a substantial shrinking of terrestrial and freshwater ecosystem habitats, in particular in Mediterranean islands (Chapters 2; 4; CCP1).

Increased aridity impacts forest ecosystems ( [[#Costa-Saura--2017|Costa-Saura et al., 2017]] ; [[#García%20Sánchez--2018|García Sánchez et al., 2018]] ). Increasing heat waves, combined with drought and land use change, reduce fuel moisture, thereby increasing fire risk, extending the duration of fire seasons and increasing the likelihood of large, severe fires ( ''high confidence'' ) ( [[#EEA--2017|EEA, 2017]] ; [[#Lozano--2017|Lozano et al., 2017]] ; [[#Peñuelas--2017|Peñuelas et al., 2017]] ; [[#Varela--2019|Varela et al., 2019]] ). Fires impact vegetation recovery after abandonment, thus transforming landscapes ( [[#González-De%20Vega--2016|González-De Vega et al., 2016]] ). At warming levels of 1.5°C, 2°C and 3°C, burnt area in Mediterranean Europe could increase by 40–54%, 62–87% and 96–187%, respectively ( [[#Turco--2018b|Turco et al., 2018b]] ), although changes are highly site dependent and also affected by management ( [[#Caon--2014|Caon et al., 2014]] ; [[#Wu--2015|Wu et al., 2015]] ; [[#Parra--2018|Parra and Moreno, 2018]] ; [[#Brotons--2019|Brotons and Duane, 2019]] ; [[#Hinojosa--2019|Hinojosa et al., 2019]] ).

Desertification occurs in large parts of the region, generally due to unsustainable land use ( [[#Peñuelas--2017|Peñuelas et al., 2017]] ). Increasing drought is projected to exacerbate desertification in North Africa and, under high warming, also southern Spain. In some areas, sclerophyllous vegetation could replace deciduous forests ( [[#Guiot--2016|Guiot and Cramer, 2016]] ). Increasing temperatures and drought could trigger dieback for some forest species such as Mediterranean oak ( [[#Sánchez-Salguero--2020|Sánchez-Salguero et al., 2020]] ), potentially also in combination with biotic factors such as pathogens ( [[#Matías--2019|Matías et al., 2019]] ).

<div id="CCP4.3.4" class="h2-container"></div>

<span id="ccp4.3.4-water-agriculture-and-food-production"></span>
=== CCP4.3.4 Water, Agriculture and Food Production ===

<div id="h2-11-siblings" class="h2-siblings"></div>

River runoff and low flows are expected to decrease (possibly by 12–15% or more) in most locations due to reduced precipitation ( [[#Giuntoli--2015|Giuntoli et al., 2015]] ; [[#Roudier--2016|Roudier et al., 2016]] ; [[#Andrew--2017|Andrew and Sauquet, 2017]] ; [[#Gosling--2017|Gosling et al., 2017]] ; [[#Marchane--2017|Marchane et al., 2017]] ; [[#Marcos-Garcia--2017|Marcos-Garcia et al., 2017]] ; [[#Marx--2018|Marx et al., 2018]] ; [[#Yeste--2021|Yeste et al., 2021]] ). Groundwater recharge is projected to decrease due to reduced inflow (WGI AR6 Chapter 11, Ranasinghe et al., 2021; [[#Koutroulis--2016|Koutroulis et al., 2016]] ; [[#Guyennon--2017|Guyennon et al., 2017]] ; [[#Braca--2019|Braca et al., 2019]] ; [[#Calvache--2020|Calvache et al., 2020]] ). Water levels in lakes and availability of reservoirs are expected to decline by up to 45% in 2100 ( [[#Koutroulis--2016|Koutroulis et al., 2016]] ; [[#Masia--2018|Masia et al., 2018]] ; [[#Okkan--2018|Okkan and Kirdemir, 2018]] ; [[#Braca--2019|Braca et al., 2019]] ; [[#Tramblay--2020|Tramblay et al., 2020]] ). The largest freshwater lake in the basin, Lake Beyşehir (Turkey), could dry out after 2070 ( [[#Bucak--2017|Bucak et al., 2017]] ). In northern Africa, surface water availability is projected to be reduced by 5–40% in 2030–2065 and by 7–55% in 2066–2095 from 1976–2005 ( [[#Tramblay--2018|Tramblay et al., 2018]] ), with decreases of runoff by 10–63% by mid-century in Morocco and Tunisia ( [[#Marchane--2017|Marchane et al., 2017]] ; [[#Dakhlaoui--2020|Dakhlaoui et al., 2020]] ). Reduced summer river flows and increasing water temperatures will constrain freshwater-cooled thermoelectric (including nuclear) power plants and hydropower plants, with possible reductions of production in the northern Mediterranean by 6–33% under 2°C and by 20–60% beyond 3°C warming ( [[#Lobanova--2016|Lobanova et al., 2016]] ; [[#Solaun--2017|Solaun and Cerdá, 2017]] ; [[#Payet-Burin--2018|Payet-Burin et al., 2018]] ; [[#Tobin--2018|Tobin et al., 2018]] ).These findings confirm the WGI AR6 [[IPCC:Wg2:Chapter:Chapter-8|Chapter 8]] statement that drought duration and frequencies and water scarcity are projected to increase drastically between 1.5°C and 2°C of GWLs (Douville et al., 2021).

Climate change will ''likely'' reduce crop yields in many areas (Table CCP4.1), mainly due to higher temperatures affecting crop phenology and the shortening of the crop growing season ( ''high confidence'' ). Additional irrigation will be needed for most crops, although the shortening of the growing season could reduce irrigation needs in some cases ( [[#Saadi--2015|Saadi et al., 2015]] ). Irrigation needs could increase by 25% in northern and two-fold in southeastern Mediterranean ( [[#Fader--2016|Fader et al., 2016]] ), with arid southern areas at risk of insufficient water resources by 2100. The use of supplemental irrigation for winter wheat could become more common in northern Mediterranean ( [[#Saadi--2015|Saadi et al., 2015]] ; [[#Ruiz-Ramos--2018|Ruiz-Ramos et al., 2018]] ).

Seawater intrusion is projected to cause additional risks in coastal aquifers, with severe impacts on agricultural productivity ( [[#Ali--2016|Ali and El-Magd, 2016]] ; [[#Wassef--2016|Wassef and Schüttrumpf, 2016]] ; [[#Pulido-Velazquez--2018|Pulido-Velazquez et al., 2018]] ; [[#Twining-Ward--2018|Twining-Ward et al., 2018]] ; [[#Omran--2020|Omran and Negm, 2020]] ). While elevated atmospheric CO 2 concentration could be positive for photosynthesis and cereal yields ( [[#Dixit--2018|Dixit et al., 2018]] ; [[#Ben-Asher--2019|Ben-Asher et al., 2019]] ; [[#Kapur--2019|Kapur et al., 2019]] ; [[#Kheir--2019|Kheir et al., 2019]] ), the net outcome for agricultural production is highly uncertain ( [[#Moriondo--2016|Moriondo et al., 2016]] ). The projected yield losses will ''likely'' reduce farm revenues, for example, in Morocco ( [[#Ouraich--2018|Ouraich and Tyner, 2018]] ), Egypt ( [[#Abd%20El-Azeem--2020|Abd El-Azeem, 2020]] ), Greece ( [[#Georgopoulou--2017|Georgopoulou et al., 2017]] ) and Israel ( [[#Zelingher--2019|Zelingher et al., 2019]] ). Given the growing water demand from agriculture and other users and the increasing competition over water resources, adaptation efforts for water supply need to be enhanced ( [[#Guyennon--2017|Guyennon et al., 2017]] ; [[#Zabalza-Martínez--2018|Zabalza-Martínez et al., 2018]] ).

Climate-driven change in pelagic production (Section CCP4.3.1), together with overfishing, will ''likely'' increase risks for fishery landings ( [[#Hidalgo--2018|Hidalgo et al., 2018]] ). By 2060, more than 20% of exploited fishes and invertebrates currently found in eastern Mediterranean could become locally extinct ( [[#Jones--2015|Jones and Cheung, 2015]] ; [[#Cheung--2016|Cheung et al., 2016]] ; [[#Balzan--2020|Balzan et al., 2020]] ). Thermophilic and/or thermal-tolerant tropical species may increasingly dominate the catch composition ( [[#Moullec--2019|Moullec et al., 2019]] ), creating possible opportunities depending on technology and consumer acceptance of new species ( [[#Hidalgo--2018|Hidalgo et al., 2018]] ). Warming and acidification may weaken mussel shells, negatively impacting shellfish aquaculture ( [[#Martinez--2018|Martinez et al., 2018]] ). High losses of clawed lobster production by the end of the century are projected under RCP4.5 ( [[#Boavida-Portugal--2018|Boavida-Portugal et al., 2018]] ). For much of the region, fisheries revenue may decrease by 15–30% by 2050 relative to 2000 under RCP8.5 ( [[#Lam--2016|Lam et al., 2016]] ).

Overall, reduced crop yields and fishery landings, combined with other factors such as rapid population growth and urbanisation, increasing competition for water and changing lifestyles, will ''likely'' impact food security, particularly in North Africa and the Middle East ( [[#Jobbins--2015|Jobbins and Henley, 2015]] ).

'''Table CCP4.1 |''' Projected risks for crop production in the Mediterranean Basin.

{| class="wikitable"
|-
! '''Crop'''

! '''Projected risk'''

|-
| Cereals and rice

| Under 2°C warming and beyond, rain-fed wheat yield in most locations could decline by 2–59%, depending on agricultural practices ( [[#Chourghal--2016|Chourghal et al., 2016]] ; [[#Dettori--2017|Dettori et al., 2017]] ; [[#Iocola--2017|Iocola et al., 2017]] ; [[#Brouziyne--2018|Brouziyne et al., 2018]] ; [[#Kheir--2019|Kheir et al., 2019]] ). Under 1.5–3°C warming and reduced rainfall, yield decreases are also projected for maize ( [[#Georgopoulou--2017|Georgopoulou et al., 2017]] ; [[#Iocola--2017|Iocola et al., 2017]] ) and barley ( [[#Bouregaa--2019|Bouregaa, 2019]] ; [[#Cammarano--2019|Cammarano et al., 2019]] ), mainly due to the shortening of the crop growing season by up to 30 days due to higher temperatures ( [[#Saadi--2015|Saadi et al., 2015]] ; [[#Bird--2016|Bird et al., 2016]] ; [[#Waha--2017|Waha et al., 2017]] ; [[#Bouregaa--2019|Bouregaa, 2019]] ). In Tunisia, cereal production may decrease by 0.79% with a 1% decrease in precipitation ( [[#Zouabi--2015|Zouabi and Peridy, 2015]] ). Reductions of rice yields in parts of the region are projected in the absence of adaptation; for example, by 6–20% in southern France and Italy in 2070 under RCP8.5 ( [[#Bregaglio--2017|Bregaglio et al., 2017]] ).

|-
| Olives

| Higher temperatures and more frequent extreme heat events around flowering will ''likely'' affect phenology. While suitable areas for olive cultivation could extend northward and to higher elevations under the A1B scenario in 2036–2065 ( [[#Tanasijevic--2014|Tanasijevic et al., 2014]] ), negative consequences for several countries are expected, including southern Spain ( [[#Gabaldón-Leal--2017|Gabaldón-Leal et al., 2017]] ; [[#Arenas-Castro--2020|Arenas-Castro et al., 2020]] ) and Tunisia ( [[#Ouessar--2017|Ouessar, 2017]] ) under 2°C warming. Under 1.5°C–2°C GWL, olive yields in northern Mediterranean locations could decrease by up to 21% ( [[#Brilli--2019|Brilli et al., 2019]] ; [[#Fraga--2020|Fraga et al., 2020]] ). A 3°C warming could cause a 15–64% drop of production of rain-fed olives in Algeria ( [[#Bouregaa--2019|Bouregaa, 2019]] ).

|-
| Vegetables

| Yields could decline by up to 45% under current irrigation in some areas by 2050 under the A1B scenario ( [[#Zhao--2015|Zhao et al., 2015]] ; [[#Georgopoulou--2017|Georgopoulou et al., 2017]] ), while a lower availability of irrigation water would lead to further losses ( [[#Saadi--2015|Saadi et al., 2015]] ) or even to non-viability of crops in some locations; for example, in Tunisia beyond 2°C warming ( [[#Bird--2016|Bird et al., 2016]] ).

|-
| Fruit trees

| Flowering of many fruit trees may be delayed, and chilling accumulation may be threatened. In Spain, under the A2 scenario, apples at maturity could be of inferior quality from mid-century, while after 2070, 28–72% of the years could have winters that do not fulfil chilling requirements ( [[#Rodríguez--2019|Rodríguez et al., 2019]] ) Similar threats for other fruit trees were found beyond 3°C GWL ( [[#Funes--2016|Funes et al., 2016]] ).

|-
| Grapevines and orchards

| Climate change could advance bud break and flowering, shortening the growing season by 20–35 days after 2060 under RCP8.5 ( [[#Fraga--2016|Fraga et al., 2016]] ; [[#Ramos--2017|Ramos, 2017]] ; [[#Leolini--2018|Leolini et al., 2018]] ; [[#Ramos--2018|Ramos et al., 2018]] ) and shifting maturation under high summer temperatures, thus affecting grape quality. Higher temperatures may increase evapotranspiration and therefore water deficit ( [[#Ramos--2018|Ramos et al., 2018]] ). Some locations may suffer from high winter temperatures, causing a lack of chilling accumulation and ultimately missed bud break ( [[#Leolini--2018|Leolini et al., 2018]] ). Early maturation may result in unbalanced wine quality through higher sugar and lower acids in the grape must after 2050 under RCP8.5 ( [[#Fraga--2016|Fraga et al., 2016]] ; [[#Koufos--2018|Koufos et al., 2018]] ). Negative impacts of climate change on table quality vines and wine grape production in Southern Europe after 2040 under RCP8.5 have been projected ( [[#Cardell--2019|Cardell et al., 2019]] ).

|-
| Dates

| Irrigation requirements for date palms in Tunisia under RCP8.5 could increase by 34% in 2050 from present to sustain date production ( [[#Haj-Amor--2020|Haj-Amor et al., 2020]] ), with adverse effects on groundwater resources.

|}

<div id="CCP4.3.5" class="h2-container"></div>

<span id="ccp4.3.5-human-health-and-cultural-heritage"></span>
=== CCP4.3.5 Human Health and Cultural Heritage ===

<div id="h2-12-siblings" class="h2-siblings"></div>

Warming is projected to impact human health, mostly through increased intensity, frequency and duration of heat waves ( ''high confidence'' ) ( [[#Guerreiro--2018|Guerreiro et al., 2018]] ; [[#Jacob--2018|Jacob et al., 2018]] ; [[#Rohat--2019|Rohat et al., 2019]] ; [[#Smid--2019|Smid et al., 2019]] ). Under current socioeconomic conditions, 53–93 million more people could be exposed to high or very high heat stress in northern Mediterranean by 2050 ( [[#Rohat--2019|Rohat et al., 2019]] ) and heat-related excess mortality could increase by more than six-fold above 3°C GWL ( [[#Gasparrini--2017|Gasparrini et al., 2017]] ). In MENA countries, the mortality risk of the elderly in 2100 could be 8–20 times higher under RCP8.5 compared to 1951–2005, and still 3–7 times higher under RCP4.5 ( [[#Ahmadalipour--2018|Ahmadalipour and Moradkhani, 2018]] ). Deaths attributable to high temperatures in the northern Mediterranean could increase by 18–20,000 in 2050 (50,000 in 2100) under RCP8.5 (1.4 and 2.6 times lower under RCP4.5) ( [[#Kendrovski--2017|Kendrovski et al., 2017]] ).

Climate change and variability may also influence the emergence of vector-, food- and water-borne diseases ( [[#Negev--2015|Negev et al., 2015]] ). Under RCP8.5, the epidemic potential of dengue fever in Southern Europe is projected to increase by 2100 ( [[#Liu-Helmersson--2019|Liu-Helmersson et al., 2019]] ), as well as the risk of infections by West Nile virus in 2050 under A1B ( [[#Semenza--2016|Semenza et al., 2016]] ). Climate-induced diseases could reduce labour productivity in the region by 2060, particularly in MENA countries ( [[#Dellink--2019|Dellink et al., 2019]] ). Overall, there is still uncertainty in projections of the future severity and distribution of diseases because of climate change due to the complex interactions between hosts, pathogens and vectors. Reductions in fruit and vegetable consumption as a result of climate change on food availability could lead to more than 20,000 deaths in 2050 under RCP8.5 from diseases caused by malnutrition ( [[#Springmann--2016|Springmann et al., 2016]] ).

Extreme high temperatures, hot days and nights and consequently cooling degree days will ''likely'' increase ( ''high confidence'' ) ( [[#Spinoni--2018a|Spinoni et al., 2018a]] ; [[#Coppola--2021|Coppola et al., 2021]] ), with specific cooling needs in cities possibly increasing by 50–278% under 2°C GWL and 134–375% beyond 3°C GWL ( [[#Cellura--2018|Cellura et al., 2018]] ). Urban heat island effects will further increase cooling needs ( [[#Salvati--2017|Salvati et al., 2017]] ; [[#Zinzi--2017|Zinzi and Carnielo, 2017]] ). Higher temperatures will increase thermal and chemical stress on materials used in many ancient buildings and sculptures, such as marble, stone and masonry ( [[#Bonazza--2009|Bonazza et al., 2009]] ; [[#Leissner--2015|Leissner et al., 2015]] ).

Many studies project a decrease of climatic comfort for tourism in the Mediterranean by 2071 to 2100, particularly during summer ( [[#Grillakis--2016|Grillakis et al., 2016]] ; [[#Jacob--2018|Jacob et al., 2018]] ; [[#Braki--2019|Braki and Anagnostopoulou, 2019]] ). There is adaptive potential in the extension of the period with favourable climatic conditions for urban tourism in northern Mediterranean cities ( [[#Scott--2016|Scott et al., 2016]] ). Water scarcity may create additional constraints for tourism ( [[#Köberl--2016|Köberl et al., 2016]] ).

Cultural heritage sites in the region face risks from coastal flooding, with 37 out of 49 cultural World Heritage sites today facing risk from a 100-year flood, and 42 of them from coastal erosion ( [[#Reimann--2018b|Reimann et al., 2018b]] ). Sea level rise will increase these risks ( ''high confidence'' ) ( [[#Lionello--2012|Lionello, 2012]] ; [[#Rizzi--2017|Rizzi et al., 2017]] ; [[#Reimann--2018b|Reimann et al., 2018b]] ; [[#Ravanelli--2019|Ravanelli et al., 2019]] ; [[#Tagliapietra--2019|Tagliapietra et al., 2019]] ). By 2100, 47 of the 49 United Nations Educational, Scientific and Cultural Organization (UNESCO) sites are projected to be at risk from coastal flooding or erosion ( [[#Reimann--2018b|Reimann et al., 2018b]] ). Beyond 2100, sea levels are committed to rise further and represent an existential threat for the high number of coastal cultural heritage located in the Mediterranean (WGI AR6 Chapter 9, Fox-Kemper et al., 2021; Chapter 13; Cross-Chapter Box SLR in Chapter 3; [[#Marzeion--2014|Marzeion and Levermann, 2014]] ).

<div id="CCP4.3.6" class="h2-container"></div>

<span id="ccp4.3.6-synthesis-of-key-risks"></span>
=== CCP4.3.6 Synthesis of Key Risks ===

<div id="h2-13-siblings" class="h2-siblings"></div>

For the Mediterranean Basin, all currently projected pathways of climate change will exacerbate climate-related risks in multiple systems and economic sectors, and for human health and well-being, amplifying current pressures on local ecosystems, economies and human well-being (Figures CCP4.7; CCP4.8; [[#Cramer--2018|Cramer et al., 2018]] ; [[#MedECC--2020|MedECC, 2020]] ). While the majority of these risks apply across the entire region, many are specific for certain sub-regions or locations.

<div id="_idContainer023" class="Figure"></div>

[[File:d7a2e8691f7c5ee283283a18c9ab98c1 IPCC_AR6_WGII_Figure_CCP4_007.png]]

'''Figure CCP4.7 |''' '''Key risks in the Mediterranean and their location across the Mediterranean region for SSP5-RCP8.''' '''5 by 2100 (Sections CCP4.3.2 –6; Table SMCCP4.2a and b for details).''' Risks to World Cultural Heritage sites from flooding or erosion due to sea level rise in multiple locations (Section CCP4.3.5) and Mediterranean river deltas are hotspots of vulnerability to climate change (Section CCP4.3.2). The population exposed to risks is mapped for an SSP5-8.5 pathway. Adaptation can reduce these risks (Section CCP4.4) (based on: [[#Reimann--2018a|Reimann et al., 2018a]] ; 2018b; [[#Wolff--2018|Wolff et al., 2018]] ).

<div id="_idContainer025" class="Figure"></div>

[[File:f5e15313109c0f56a6297c8151b58a9e IPCC_AR6_WGII_Figure_CCP4_008.png]]

'''Figure CCP4.8 |''' '''Summary of key risks for the Mediterranean (Sections CCP4.''' '''3.2–8; Table SMCCP4.2a–h for details).''' Coastal risks include one burning ember displaying additional risks due to climate change as specific GWL are exceeded (Coastal risks), and one burning ember describing additional risks due to committed sea level rise at timescales of centuries and millennia for long-living infrastructure and cultural heritage (WGI AR6 Chapter 9, Fox-Kemper et al., 2021; Marzeion et al., 2014; [[#Marzeion--2014|Marzeion and Levermann, 2014]] ; [[#Clark--2016|Clark et al., 2016]] ; see SMCCP4.2h).

<div id="CCP4.4" class="h1-container"></div>

<span id="ccp4.4-adaptation-and-sustainable-development-in-the-mediterranean-basin"></span>