Methodology and data for quantifying storm erosion potential considering sea level rise.

This dataset quantifies storm intensity of approximately 130 unique historical storms along the New Jersey coastline from 1980 to 2014 for three separate sea level conditions. Namely, (1) as observed in the historical record; (2) detrended to 1997 mean sea level and (3) adjusted to the 2050 and 2100 sea level rise scenarios presented in the International Panel on Climate Change's (IPCC) Sixth Assessment Report (AR6). Projected sea level scenarios are adjusted to include local vertical land movement. Storm intensity is quantified in terms of erosion potential, considering the combination of total water level, wave heights, and storm duration. The observational dataset includes both tropical and extratropical storms and quantifies both the cumulative (duration) and peak (single hour) storm intensity for each storm and sea level rise (SLR) condition. Additionally, hourly time series of wave characteristics and water levels are provided at 13 locations along the New Jersey coast, facilitating hydrodynamic forcing of nearshore models. The dataset provides the means and methods to directly compare historical storms under future SLR conditions.

Characterizing fluvial impact on the biochemical composition of particulate organic matter in the Laptev Sea and Western East Siberian Sea during the late summer of 2018.

The Laptev Sea (LS) and Western East Siberian Sea (W-ESS) are paradigmatic examples of seas dominated by terrestrial organic matter, attributed to substantial Siberian River discharges and coastal erosion. The influx of terrestrial organic matter significantly alters the biochemical composition of particulate organic matter (POM) in these Arctic coastal regions, potentially reducing the nutritional quality available to higher trophic levels. This study investigated the origin and qualitative characteristics of POM in the LS and W-ESS during the late summer of 2018 by analyzing elemental ratios (C/N ratio), stable carbon isotopes (δ13C), and biochemical compositions (biomolecular and amino acid (AA) compositions). The conspicuously depleted δ13C values (mean ± standard deviation (SD) = -30.2 ± 0.5 ‰) and alongside elevated molar C/N ratios (mean ± SD = 18.1 ± 6.2) suggest that terrestrial organic matter is the predominant source of POM in the study area. Although carbohydrates (CHO) were the dominant biomolecules, their prevalence was higher in the river-influenced W-ESS region (67.7 ± 6.6 %) than in the LS region (58.6 ± 13.9 %; p < 0.05). Furthermore, the CHO composition was closely associated with freshwater content and river fraction, suggesting that the heightened contribution of CHO may stem from terrestrial organic matter delivered by river inputs. Lower concentrations of particulate hydrolyzable AA (PAA) and carbon and nitrogen normalized yields of AAs (AA-POC% and AA-PON%) along with reduced contribution of glycine suggested a substantial contribution of terrestrial POM to both LS and W-ESS POM. Overall, this study provides valuable insights into the terrestrial influence on POM composition in Arctic marine ecosystems, emphasizing the need for continued monitoring of the consequences of terrestrial carbon inputs in the changing Arctic environment.

Coastal erosion and flooding risk assessment based on grid scale: A case study of six coastal metropolitan areas.

Coastal areas, situated at the critical juncture of sea-land interaction, are confronted with significant challenges from coastal erosion and flooding. It is imperative to evaluate these risks and offer scientific guidance to foster regional sustainable development. This article developed a coastal risk assessment model based on grid scale, integrating both coastal exposure and socio-ecological environment. Fourteen indicators were selected, aiming to offer a systematic approach for estimating and comparing disaster risks in coastal areas. This risk assessment model was applied to Shanghai, New York, Sydney, San Francisco, Randstad, and Tokyo metropolitan areas. The results indicate: (1) Accounting for the protective role of habitat types like mangroves and the distance attenuation effect offered a more precise representation of hazard situation; (2) The integration of the Game Theory weighting method with both subjective Analytic Hierarchy Process and objective CRITIC weighting enhanced the scientific validity and rationality of the results by minimizing deviations between subjective and objective weights; (3) Shanghai exhibited the highest average hazard and vulnerability, San Francisco had the lowest average hazard and Sydney had the lowest average vulnerability; In terms of comprehensive risk, Shanghai possessed the highest average risk, while Sydney presented the lowest. The proposed model framework is designed to swiftly identify high-risk zones, providing detailed information references for local governments to devise efficacious risk management and prevention strategies.

Coastal adaptation and migration dynamics under future shoreline changes.

In this study, we present a novel modeling framework that provides a stylized representation of coastal adaptation and migration dynamics under sea level rise (SLR). We develop an agent-based model that simulates household and government agents adapting to shoreline change and increasing coastal flood risk. This model is coupled to a gravity-based model of migration to simulate coastward migration. Household characteristics are derived from local census data from 2015, and household decisions are calibrated based on empirical survey data on household adaptation in France. We integrate projections of shoreline retreat and flood inundation levels under two Representative Concentration Pathways (RCPs) and account for socioeconomic development under two Shared Socioeconomic Pathways (SSPs). The model is then applied to simulate coastal adaptation and migration between 2015 and 2080. Our results indicate that without coastal adaptation, SLR could drive the cumulative net outmigration of 13,100 up to as many as 21,700 coastal inhabitants between 2015 and 2080 under SSP2-RCP4.5 and SSP5-RCP8.5, respectively. This amounts to between 3.0 %-3.7 % of the coastal population residing in the 1/100-year flood zone in 2080 under a scenario of SLR. We find that SLR-induced migration is largely dependent on the adaptation strategies pursued by households and governments. Household implementation of floodproofing measures combined with beach renourishment reduces the projected SLR-induced migration by 31 %-36 % when compared to a migration under a scenario of no adaptation. A sensitivity analysis indicates that the effect of beach renourishment on SLR-induced migration largely depends on the level of coastal flood protection offered by sandy beaches. By explicitly modeling household behavior combined with governmental protection strategies under increasing coastal risks, the framework presented in this study allows for a comparison of climate change impacts on coastal communities under different adaptation strategies.

Coastal evolution and future projections in Conde County, Brazil: A multi-decadal assessment via remote sensing and sea-level rise scenarios.

Global sea levels, having risen by approximately 20 cm since the mid-19th century, necessitate a critical examination of their impacts on shoreline dynamics. This research evaluates the historical (1985-2022) and future shoreline changes in Conde County, Paraíba State, Brazil, an area of significant touristic interest. Employing Landsat satellite imagery, the study utilized the Digital Shoreline Analysis System (DSAS) and a Kalman filter algorithm for cloud removal, while also assessing land use and land cover changes using data from the MapBiomas Project for 2000, 2010, and 2020. These analyses informed projections of potential inundation under various sea-level rise (SLR) scenarios: 1, 2, 5, and 10 m. Key findings revealed a negative average coastline change rate of -0.27 m/year from 1985 to 2022, indicative of erosive trends likely accelerated by human activities. Long-term projections for 2032 and 2042 anticipate continued erosion in areas identified as highly vulnerable. The SLR scenario analysis underscores the urgent need for adaptive climate measures; while a 1- or 2-meter SLR presents limited immediate effects, a 5-meter rise could lead to significant inundation across key sectors, including urban and agricultural landscapes. The projected severity of a 10-meter SLR necessitates immediate, comprehensive interventions to safeguard both natural and human systems.

Victim of changes? Marine macroalgae in a changing world.

BACKGROUND: Marine macroalgae ('seaweeds') are a diverse and globally distributed group of photosynthetic organisms that together generate considerable primary productivity, provide an array of different habitats for other organisms, and contribute many important ecosystem functions and services. As a result of continued anthropogenic stress on marine systems, many macroalgal species and habitats face an uncertain future, risking their vital contribution to global productivity and ecosystem service provision. SCOPE: After briefly considering the remarkable taxonomy and ecological distribution of marine macroalgae, we review how the threats posed by a combination of anthropogenically induced stressors affect seaweed species and communities. From there we highlight five critical avenues for further research to explore (long-term monitoring, use of functional traits, focus on early ontogeny, biotic interactions and impact of marine litter on coastal vegetation). CONCLUSIONS: Although there are considerable parallels with terrestrial vascular plant responses to the many threats posed by anthropogenic stressors, we note that the impacts of some (e.g. habitat loss) are much less keenly felt in the oceans than on land. Nevertheless, and in common with terrestrial plant communities, the impact of climate change will inevitably be the most pernicious threat to the future persistence of seaweed species, communities and service provision. While understanding macroalgal responses to simultaneous environmental stressors is inevitably a complex exercise, our attempt to highlight synergies with terrestrial systems, and provide five future research priorities to elucidate some of the important trends and mechanisms of response, may yet offer some small contribution to this goal.

Marine Transgression in Modern Times.

Marine transgression associated with rising sea levels causes coastal erosion, landscape transitions, and displacement of human populations globally. This process takes two general forms. Along open-ocean coasts, active transgression occurs when sediment-delivery rates are unable to keep pace with accommodation creation, leading to wave-driven erosion and/or landward translation of coastal landforms. It is highly visible, rapid, and limited to narrow portions of the coast. In contrast, passive transgression is subtler and slower, and impacts broader areas. It occurs along low-energy, inland marine margins; follows existing upland contours; and is characterized predominantly by the landward translation of coastal ecosystems. The nature and relative rates of transgression along these competing margins lead to expansion and/or contraction of the coastal zone and-particularly under the influence of anthropogenic interventions-will dictate future coastal-ecosystem response to sea-level rise, as well as attendant, often inequitable, impacts on human populations.

Traditional vs. novel approaches to coastal risk management: A review and insights from Italy.

Coastal areas frequently face critical conditions due to the lack of adequate forms of land use planning, environmental management and inappropriate coastal risk management, sometimes leading to unexpected and undesired environmental effects. Risk management also involves cultural aspects, including perception. However, the acknowledgement of risk perception by stakeholders and local communities, as one of the social pillars of risk analysis, is often lacking. Starting from an overview of the risk concept and the related approaches to be addressed, the paper investigates the evolution of coastal risk management with a focus on the Italian case study. Despite the design and adoption of national policies to deal with coastal risks, coastal management still shows in Italy a fragmented and poorly coordinated approach, together with a general lack of attention to stakeholder involvement. Recent efforts in the design of plans aiming at reducing risks derived from climate change and mitigating their impacts (National Strategy on Climate Change Adaptation; National Climate Change Adaptation Plan; National Recovery and Resilience Plan activities) should be effective in updating knowledge about climate change risks and in supporting national adaptation policies.

Exploratory modelling of the impacts of sea-level rise on the Sundarbans mangrove forest, West Bengal, India.

In this paper we conduct exploratory simulations of the possible evolution of the Indian Sundarbans mangroves to 2100 under a range of future sea-level rise (SLR) scenarios, considering the effects of both inundation and shoreline erosion. The Sea Level Affecting Marshes Model (SLAMM) is used to simulate habitat transitions due to inundation and these outputs are combined with an empirical model of SLR-driven shoreline erosion. A set of plausible climate-induced SLR scenarios are considered, together with delta subsidence and constrained vertical sediment accretion. Significant mangrove decline is found in all cases: the greater the rise in sea level the greater the losses. By the end of the century, the Indian Sundarbans mangroves could lose between 42 % and 80 % of their current area if current management is continued. Managed realignment could offset these losses but at the expense of productive land and the migration of the human population.

Coastal erosion and climate change: A review on coastal-change process and modeling.

Coastal erosion is a normal process of nature. However, the rate of coastal erosion, and the frequency and intensity of coastal flooding events, are now on the rise around the world due to the changing climate. Current responses to coastal erosion are primarily determined by site-specific factors, such as coastal elevation, coastal slope, coastal features, and historical coastline change rate, without a systematic understanding of the coastal-change processes in the context of climate change, including spatiotemporal changes in sea level, regional changes in wave climate, and sea ice coverage. In the absence of a clear understanding of the coastal-change processes, most of the current coastal responses have been built upon a risky assumption (i.e., the present-day coastal change will persist) and are not resilient to future climate change. Here, we conduct a literature review to summarize the latest scientific understanding of the coastal-change processes under climate change and the potential research gaps towards the prediction of future coastal erosion. Our review suggests that a coupled coastal simulation system with a nearshore wave model (e.g., SWAN, MIKE21, etc.) can play a critical role in both the short-term and long-term coastal risk assessment and protective measure development.

Future scenarios in the former oil capital: coastal flooding and social vulnerability in Macaé, RJ.

The accelerated urban growth in Macaé had important consequences on socio-spatial organization, especially about housing spaces that became increasingly difficult to be accessed by the low-income population. The most devalued lands, such as mangroves and floodplains, were occupied by the low-income population. The proposal highlighted in this project focuses directly on the problem of rising sea levels and flooding in the urban space of Macaé, which is of social interest. A simulation of future scenarios with sea level rise above the current one, allowing the identification of areas flooded by marine transgression on a time scale of 100 years (for the year 2100). For this, the rate was chosen for the simulation: the greenhouse gas scenario RCP8.5, as given in IPCC's Fifth Assessment Report (AR5) of 2014. A radiative forcing that corresponds to more than 700 ppm CO2-eq, but less than 1500 ppm, the projected increase is 1 m to more than 3 m (medium confidence) and more than 3 m (medium confidence). This assessment is based on the average confidence in the contribution from thermal expansion and low confidence in the modeled contribution modeled contribution of the ice sheets. Therefore, the climate change-induced global mean sea level rise is caused by thermal expansion of ocean water and ocean mass gain, the latter being mainly due to a decrease in land ice mass. The estimated sea-level rise used for the projection of this study is 2.15, as proposed by Grinsted et al. in 2009.

Effects of porous media thickness and its hydraulic gradient history on the formation of sand boils: Experimental investigation.

Sand boils occur where groundwater discharges to the land surface under sufficient hydraulic gradient to cause internal erosion and the upward transport of particles. A proper understanding of sand boil processes is essential in evaluating a wide range of geomechanical and sediment transport situations under which groundwater seepage occurs, such as the effects of groundwater discharge on beach stability. Although various empirical methods have been developed to estimate the critical hydraulic gradient (icr) leading to sand liquefaction, a prerequisite for sand boil occurrence, the effect of sand layer thickness and the implications of driving head fluctuations on the formation and reformation of sand boils have not been explored previously. This paper uses laboratory experiments to study sand boil formation and reformation for various sand thicknesses and hydraulic gradients to fill this knowledge gap. Sand layer thicknesses of 90 mm, 180 mm and 360 mm were adopted in evaluating sand boil reactivation, which was created by imposing hydraulic head fluctuations. While the first experiment (i.e., 90 mm sand layer) yielded a value for icr smaller (by 5%) than Terzaghi's (1922) value, the same theory underestimated icr by 12% and 4% for 180 mm and 360 mm sand layers, respectively. Moreover, icr needed for the reformation of sand boils decreased by 22%, 22% and 26% (relative to icr applicable to the initial sand boil) for the 90 mm, 180 mm and 360 mm sand layer thicknesses, respectively. We conclude that the formation of sand boils requires consideration of sand depth and the history of sand boil formation, particularly in relation to sand boils that form (and potentially reform) under oscillating pressures (e.g., tidal beaches).

A quantitative analysis of multi-decadal shoreline changes along the East Coast of South Korea.

South Korea's east coast is facing several issues related to coastal erosion because of sea-level rise, typhoon-induced storm surges, and various coastal development projects. In recent decades, high storm waves have frequently appeared on the east coast, causing casualty, beach erosion, and coastal infrastructure damage, drawing significant public attention. Thus, we analyzed the multi-decadal shoreline changes to understand the coastal dynamics and the forces responsible for the spatio-temporal changes along the 173 km coastline. The shorelines covering 38 years between 1984 and 2022 were derived from Landsat images and the change statistics, i.e., linear regression rate (LRR), endpoint rate (EPR), weighted linear regression (WLR), and net shoreline movement (NSM), were calculated at a 100 m alongshore intervals using Digital Shoreline Analysis System (DSAS), revealed several distinct behaviors of shoreline position. The long-period (1984-2022) assessment showed an average shoreline change rate (LRR) of 0.17 m/year with an estimated mean erosion and deposition rate of -0.57 and 2.07 m/year, respectively. The long-term surface gain and loss of the backshore region exhibited that the net surface gain of the east coast is 421.13 ha, and the net loss is 181.82 ha. The assessment of decadal shoreline changes showed a cyclic pattern of erosion (from 1984-1990 and 1999-2010) and accretion (from 1990-1999 and 2010-2022). Furthermore, a secondary level of investigation was conducted to address a wider variety of coastal behaviors by segmenting shoreline change rates based on coast types and average slopes along coastlines. It was observed that the frequent coastal deformation is associated with a flatter beach compared to a steep one. This study found that the artificial structures constructed along the east coast have not completely solved or stopped the erosion issues but shifted it from one location to another. The analysis of local and regional shoreline changes had shown that typhoon-induced storm surges, high storm waves, and anthropogenic activities like encroachment and the development of artificial coastal structures were the primary drivers of coastline changes along the east coast. Finally, we proposed a decision-making classification scheme that can be used to determine the mechanism of decision for protective and preventive measures against further coastal deterioration.

Adaptation of coastal defence structure as a mechanism to alleviate coastal erosion in monsoon dominated coast of Peninsular Malaysia.

The complexity of the coastal environment and the advent of climate change cause coastal erosion, which is incontrovertibly a significant concern worldwide, including Peninsular Malaysia, where, the coast is threatened by severe erosion linked to anthropogenic factors and monsoonal wind-driven waves. Consequently, the Malaysian government implemented a mitigation plan using several coastal defence systems to overcome the coastal erosion problem. This study assesses coastal erosion management strategies along a monsoon-dominated coasts by evaluating the efficacy of coastal protection structures against the coast. To this end, we analysed 244 km of the coastline of Terengganu, a federal state located on the east coast of Peninsular Malaysia. Due to a higher frequency of storms and the ensuing inception of high wave energy environments during the northeast monsoon (relative to southwest monsoon), the study area is the most impacted region in Malaysia with regard to coastal erosion. Fifty-five (55) coastal defence structures were detected along the Terengganu coastline. The Digital Shoreline Analysis System (DSAS) was utilised to compute changes in the rate statistics for various historical shoreline positions along the Terengganu coast to assess the efficacy of the defence structures. Additionally, this study acquired the perception of the existing coastal management strategies through an interview session with the concerned stakeholders. The rate statistics revealed the effectiveness and impact of the coastal defence structure on the coastline. Assessing the functionality of the coastal defence structures shed light on the present scenario of coastal erosion management. Greater efficacy and lower impact of coastal defence structures are prescribed for coastal erosion management strategies across the monsoon-dominated coast.

Combining remote sensing analysis with machine learning to evaluate short-term coastal evolution trend in the shoreline of Venice.

With increasing storminess and incessant sea-level rise, coastal erosion is becoming a primary issue along many littorals in the world. To cope with present and future climate change scenarios, it is important to map the shoreline position over years and assess the coastal erosion trends to select the best risk management solutions and guarantee a sustainable management of communities, structures, and ecosystems. However, this objective is particularly challenging on gentle-sloping sandy coasts, where also small sea-level changes trigger significant morphological evolutions. This study presents a multidisciplinary study combining satellite images with Machine Learning and GIS-based spatial tools to analyze short-term shoreline evolution trends and detect erosion hot-spots on the Venice coast over the period 2015-2019. Firstly, advanced image preprocessing, which is not frequently adopted in coastal erosion studies, was performed on satellite images downloaded within the same tidal range. Secondly, different Machine Learning classification methods were tested to accurately define shoreline position by recognizing the land-sea interface in each image. Finally, the application of the Digital Shoreline Analysis System tool was performed to evaluate and visualize coastal changes over the years. Overall, the case study littoral reveals to be stable or mainly subjected to accretion. This is probably due to the high presence of coastal protection structures that stabilize the beaches, enhancing deposition processes. In detail, with respect to the total length of the considered shoreline (about 83 km), 5 % of the coast is eroding, 36 % is stable, 52 % is accreting and 7 % is not evaluable. Despite a significant coastal erosion risk was not recognized within this region, well-delimited erosion hot-spots were mapped in correspondence of Caorle, Jesolo and Cavallino-Treporti municipalities. These areas deserve higher attention for territorial planning and prioritization of adaptation measures, facing climate change scenarios and sea-level rise emergencies in the context of Integrated Coastal Zone Management.

An integrated approach for coastal cliff susceptibility: The case study of Procida Island (southern Italy).

Procida Island, located in the Gulf of Naples (southern Italy), is characterized by steep cliffed coasts, articulated in a succession of headlands and small embayments with narrow pocket beaches, such as Ciraccio and Chiaia, often characterized by instability. In this study, a methodology for coastal cliff susceptibility assessment has been conceived based on hydraulic and geomorphological characteristics, which supported the construction of a Cliff Stability Index (CSI). The geomorphological characteristics are related to the whole cliff face, the cliff material resistance, and the cliff failure mechanisms. The hydraulic actions on the cliff are related to the wave impact which is exerted by the breaking waves once the wave run-up distance exceeds the beach width. The index takes into account the slope of the cliff, the rock strength, the wave energy at the cliff base produced by the broken wave and the presence of defence structures at the cliff base. The resulting index classification, obtained by addition of the partial sub-indices, has been compared with the observed coastal cliff evolution from 1954 to 2021.

Temporal analysis of environmental quality of Ponta Negra beach (Natal-RN) related to coastal erosion: what has changed in 10 years?

Ponta Negra beach is one of the main tourist destinations in the state of Rio Grande do Norte (Brazil), which is used by many tourists. This study aimed to perform a temporal analysis of the environmental quality of the beach related to coastal erosion, considering environmental and anthropic parameters at two different times, 10 years apart. The total length of the beach (3 km) was subdivided into 10 sections of approximately 300 m numbered 1-10, from south to north. Eight parameters were assessed based on an attribute scale ranging from the worst to the best possible quality (1-4) found in each section. The sum of the parameters was used to determine the final score. To determine the level of environmental quality, four conditions were considered (excellent, good, regular, and bad). Compared with the first sampling period, the results indicated that 50% of the beach showed reduction in environmental quality. The "excellent" condition, obtained in the first sampling period for two of the sections, was not repeated in the second period. Two situations were responsible for the decrease in beach quality over time: the erosive process that took place after 2012 and consequent reduction in vegetation cover and width of the beach environment. The current state of the beach and its gradual loss of quality over the years indicate an unpromising trend towards recovery. The methodology used in this study can be easily repeated in other locations with similar problems, generating data that can help in understanding local conditions.

Assessing of detached breakwaters and beach nourishment environmental impacts in Italy: a review.

Coastal regions are exposed to natural phenomena such as sea waves, sea level rise, climate change, and flooding events. These factors, along with human pressures, lead to an increase in coastal erosion. In response, hard engineering measures were realized as breakwaters and groins, to oppose erosion processes along the sandy beaches of the Italian coastline. These types of defense systems showed negative impacts on landscapes, ecosystems, and expected results. Additionally, the use of coastal revetments, submerged sandbars, soil bioengineering, and beach nourishment projects were used to defend seaboard areas from the risk of a growing shore withdrawal. Among these soft solutions, beach nourishment is becoming an environmentally friendly method to control shoreline erosion, increasing the width of sandy beaches to guarantee a better tourist use of coastal regions and to add a greater buffer between the shoreline and existing infrastructure. In recent times, nourishment projects have been combined with other protective measures, such as submerged sandbars and underwater detached breakwaters, limiting the loss of sediments from sandy beaches and allowing better protection from stormy events. These mixed solutions ensure effective coastal protection by maintaining the width of sandy beaches for tourist use, guaranteeing the environmental safeguard of the coastal ecosystems. In order to achieve the best result with these types of projects, a close collaboration between coastal engineers, geologists, biologists, and policymakers toward integrated coastal zone management is necessary. The study described in this paper has taken the form of a literature review regarding both the negative environmental impacts and the benefits associated with the use of old and new coastal defense systems.

Coastal Erosion and Flood Coping Mechanisms in Southern Thailand: A Qualitative Study.

Communities in coastal regions are affected by the impacts of extreme climatic events causing flooding and erosion. Reducing the impacts of flood and erosion in these areas by adopting coping strategies that fortify the resilience of individuals and their localities is desirable. This study used summative content analysis to explore the coping mechanisms of coastal communities before, during, and after various dangers relating to flooding and erosion. The findings from the study show that effective surveillance systems, disaster preparedness, risk mapping, early warning systems, availability of databases and functional command systems, as well as reliable funding are essential to efficiently cope with hazards of coastal flooding and erosion. As flooding and erosion have been predicted to be more severe due to climate change in the coming years, the adoption of effective natural and artificial mechanisms with modern technologies could help coastal regions to be more resilient in coping with the dangers associated with flooding and erosion. Pragmatic policies and programs to this end by actors are critical to averting crises induced by flooding and erosion in coastal areas.

Adapting to heatwave-induced seagrass loss: Prioritizing management areas through environmental sensitivity mapping.

Seagrass meadows support complex species assemblages and provide ecosystem services with a multitude of socio-economic benefits. However, they are sensitive to anthropogenic pressures such as coastal development, agricultural run-off, and overfishing. The increasing prevalence of marine heatwaves (MHWs) due to climate change poses an additional and growing threat. In this study, we apply the environmental sensitivity mapping approach MESA (Mapping Environmentally Sensitive Assets) to explore the potential consequences of MHWs on the ecosystem services that Posidonia oceanica provides to coastal communities. Under the intermediate climate change scenario Representative Concentration Pathway 4.5, Mediterranean marine heatwaves will be severe by 2050, and will very likely increase mortality of P. oceanica. However, the societal risk of seagrass loss is not evenly distributed across the Mediterranean. The spatial distribution of socio-economic implications of seagrass loss is highlighted through two case studies on seagrass-dependent fisheries and coastal hazards. Coastal communities in Tunisia and Libya show very high sensitivity to a loss of fisheries due to a combination of increasingly intense and frequent MHWs, coupled with high proportions of regional seagrass-dependent fisheries catch. The coastlines of Italy, Tunisia, and Cyprus are shown to potentially be highly sensitive to loss of seagrass due to high levels of coastal hazards, and seagrass meadows susceptible to MHW-induced degradation. These coastlines are likely to suffer from reduced coastal protection services provided by intact seagrass meadows. We demonstrate the implications of MHWs for ecosystem service provision to coastal communities in the Mediterranean and the need for policy instruments to help mitigate and adapt to its effect. We also highlight the potential for environmental sensitivity mapping to help support policymakers with rapid screening tools to prioritize resources more effectively to areas where in-depth local planning is needed.