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Low‐relief coastal landscapes are at major risk of rising sea levels, as vertical changes in relative sea level have far‐reaching lateral effects. Integration of a dense 2D grid of seismic reflection data with sedimentological and geotechnical data obtained in two offshore wind farm zones allows detailed documentation of postglacial landforms and environmental change over a 1,021 km2 area in the western sector of the southern North Sea. Following the retreat of Last Glacial Maximum ice sheets from the southern North Sea, the resulting postglacial terrestrial landscape provided a surface for peatland formation as climate started to warm and the water table rose in response to relative sea‐level rise. Southward‐draining fluvial networks formed contemporaneously with the peatlands, and remnants of this terrestrial wetland landscape are buried beneath Holocene marine sediments. Distinctive isolated incisional features and discrete widening of fluvial channels that cut through the peats are interpreted as either tidal ponds or relict tidal channels. These features record the evolution of this landscape through the Early Holocene as marine transgression inundated a low‐relief coastal plain. The erosion of the peatlands observed in the cores, the patchy preservation of the organic wetland landscape, and the lack of preserved barrier systems recorded by the seismic reflection data suggest that the rate of relative sea‐level rise outpaced sediment supply during the Late Postglacial and Early Holocene in this area of the southern North Sea. In a regional context, the southward draining river channels contrast to northward fluvial drainage to the North Sea, pointing to a subtle drainage divide in the palaeolandscape and the presence of a low‐relief land bridge separating the North Sea and the English‐Channel/La Manche during the Early Holocene. The documented scenario of rising sea levels combined with decreasing sediment supply in a low‐relief setting is a situation faced by many global deltas and coastlines, which makes the southern North Sea a crucial archive of coastal landscape change. [ABSTRACT FROM AUTHOR]

Bohai Bay is a typical area of global change research in East Asia, due to its unique geographical location and shallow water environment. In this paper, we present the results of a study of grain-size, geochemistry, pollen and algae of a middle to late Holocene sediment core from Haixing wetland, which located on the west coast of Bohai Bay. The results show that: 1) Prior to 6700 cal a B.P., the content of Cl, Sr/Ca ratio were the highest, end-member analysis of grain size suggested EM2 were dominant, which is characteristic of marine sediment and the concentrations of Pediastrum and Typha (indicating a freshwater environment) pollen were lowest, overall indicating the maximum of relative sea level; 2) During 6700–5000 cal a B.P., and the Ti and K contents, EM1 (lacustrine sedimentary component) increased substantially, EM2 decreased, and EM3 (fluvial sedimentary component) began to appear. The concentrations of Pediastrum , Dinophyceae and Typha pollen began to increase. All these indicating that the relative sea level began to fall and the study area became a lagoon environment; 3) During 5000–3500 cal a B.P. the Ti and K content increased further; EM1 was dominant, EM2 was rare, indicating that the relative sea level decreased further and the lagoon gradually became enclosed; 4) After 3500 cal a B.P., the Ti content reached its maximum and the Cl content and Sr/Ca ratio decreased to their lowest levels. EM1 was dominant and EM2 was virtually absent; dinoflagellate cysts almost disappeared and there was large increase of Typha pollen, indicating the complete exclusion of a marine influence during most of this period. However, during 2500–2000 cal a B.P. the Cl and the Sr/Ca ratio increased slightly once again, indicating a transient transgression. [ABSTRACT FROM AUTHOR]

& Olariu, C. (2018) Mixed-energy process interactions read from a compound-clinoform delta (paleo-orinoco Delta, Trinidad): preservation of river and tide signals by mud-induced wave damping. Keywords: hydrodynamics; sedimentology; shallow-marine EN hydrodynamics sedimentology shallow-marine 206 212 7 05/30/23 20230401 NES 230401 Sketch diagram illustrating the various hydrodynamic processes occurring in coastal to shelf environments, with numbers referring to articles from this issue. Furthermore, certain systems are or were dominated by a single depositional process, yet their deposits lack any characteristics commonly assigned to such systems: for example, the Venice lagoon is tide-dominated, yet no tidal rhythmites are preserved in the sediments (Ghinassi et al., [19]). [Extracted from the article]

Coastal erosion in 45 sandy beaches covering nearly 2000 km along the tectonically active Chilean coast is assessed during the last four decades. The historical analysis is based on the assessment of decadal changes of the shoreline position extracted from topographic surveys, aerial photographs, satellite images and survey maps using the DSAS software. Results show that 80% of the sites presented erosion rates (>−0.2 m/y), 7% beaches accreted (>0.2 m/y) while 13% remained stable. Eroded beaches include headland bay beaches, embayed and pocket beaches. A discussion on the possible causes explaining these results is conducted. While changes in offshore wave climate are spatially smooth within the region, relative mean sea level changes are highly variable and modulated by tectonic activity; the reduction of the sediment supply explains erosion rates in few cases. [ABSTRACT FROM AUTHOR]

To review our current understanding of coastal sea level change and variability, from seasonal to multi-decadal time scales, and characterize the relationship between large-scale open ocean processes and coastal sea level; To assess the ability of ocean model-data syntheses in estimating coastal sea level variations and of atmosphere-ocean global coupled models in projecting future sea level changes. The paper by Gregory et al. ([4]) defines various concepts and terms associated with sea level and sea level changes and proposes a revised terminology to be adopted when discussing sea level and related issues. Poor knowledge of the different contributions to sea level change leads to inaccuracies in the description of the uncertainties in coastal sea level projections. [Extracted from the article]

Wind, waves, tides, sediment supply, changes in relative sea level and human activities strongly affect shorelines, which constantly move in response to these processes, over a variety of timescales. Thus, the implementation of sound coastal zone management strategies needs reliable information on erosion and/or deposition processes. To suggest a feasible way to provide this information is the main reason for this work. A chain approach is proposed here, tested on a vulnerable coastal site located along southern Italy, and based on the joint analysis of field data, statistical tools and numerical modeling. Firstly, the coastline morphology has been examined through interannual field data, such as aerial photographs, plane-bathymetric surveys and seabed characterization. After this, rates of shoreline changes have been quantified with a specific GIS tool. The correlations among the historical positions of the shoreline have been detected by statistical analysis and have been satisfactorily confirmed by numerical modeling, in terms of recurrent erosion–accretion area and beach rotation trends. Finally, based on field topographic, sediment, wave and wind data, the response of the beach through numerical simulation has been investigated in a forecasting perspective. The purpose of this study is to provide a feasible, general and replicable chain approach, which could help to thoroughly understand the dynamics of a coastal system, identify typical and recurrent erosion–accretion processes, and predict possible future trends, useful for planning of coastal activities. [ABSTRACT FROM AUTHOR]

Sea level variability affected by sea water mass is strongly associated with global, regional and local climate. In this context, the eastern Mediterranean Sea has been intensively investigated in recent decades because of its sensitivity to climatic and environmental variables, due to the influence of the Eastern Mediterranean Transient (EMT). The sea level in Israel during the Crusader period (12th-13th centuries CE) was found to be −0.5 ± 0.20 m relative to the present mean sea level (MSL). The difference between the Crusader sea level and the present-day MSL raises some questions which bring us to the aim of this study: estimating the timeline of the changes in sea level elevation in the eastern Mediterranean over the last two centuries. Archaeological evidence from areas of low tidal range, such as the Mediterranean Sea, can provide significant information on sea level changes for times when instrumental measurements where not yet available (e.g., before 1955 in Israel). The method employed in this study integrates two dimensions: The vertical—estimating the changes in sea levels relative to the present MSL, based on archaeological evidence; and the horizontal—determining the coastline changes, based on coastal architectural and geomorphological structures appearing in historical maps. Both the structural and the cartographic evidence for sea level changes date to the 19th Century, and indicate a rise of 0.36 m over the last two centuries. Findings attesting to horizontal changes, indicate a gradual migration of the coastline landward, to the east since 1863 and a rapid change in the coastal geomorphology at the beginning of the 20th century. The sea level increase from the 19th century might be, in part, a consequence of regional trends and, in part, a result of a gap between method accuracy (archaeology and modern measurements). Nevertheless, the drastic change in the geomorphology of the coastline may indicate an extreme meteorological event, such as a storm at sea, accompanied by a local rise of sea level, but further research is required to verify this. [ABSTRACT FROM AUTHOR]

In the Fethiye Gulf on the southwest coast of Turkey, several submerged archaeological sites provide useful data about relative sea level changes since the Byzantine period. The current elevations of contemporary archaeological structures were measured to determine the amount of relative sea level change. The archaeological sea level markers in this seismically active region provide new data about the amount and period of relative sea level rise. Taking into consideration the time of the last use of the structures, instead of their time of construction, three different rates of vertical land movement of 2.18 ± 0.3, 2.96 ± 0.3, and 3.29 ± 0.5 mm/yr were estimated. These data indicate that tectonic activity differs from region to region, most likely related to local normal faults in the gulf. Recent earthquakes have confirmed active seismicity in this area. These results demonstrate that the changing sea levels in the Fethiye Gulf have been strongly influenced by vertical tectonic movement over the last 1,400 years. Results also contribute to studies of future coastal changes in the Fethiye Gulf and its surroundings. [ABSTRACT FROM AUTHOR]

The coastal zone of Zanzibar, Tanzania, is culturally, socially, economically, and ecologically unique but there is a lack of baseline information about its state characteristics as a whole. This paper provides a holistic assessment of the environmental and socio-economic settings of the Zanzibar coastal zone with its unusual physiographic characteristics and key habitats such as coral reefs, mangroves, and seagrass meadows. The human livelihood of Zanzibar is unmistakably coastal with its many cultural adaptations but the most recent decades have shown drastic changes in the prevailing seaborne and coastal activities. This development has not been without disputes among the different interest groups. The driver-pressure-state-impact-response approach allows to scrutinize the socio-ecological system circles of the Zanzibar coastal zone. Systematically, the approach provides interlink of the drivers and with their impacts on the socio-economic systems and the appropriate responses necessary to combat the impacts. The main drivers identified to be the population increase, urbanization with settlement expansion, and the rapid expansion of the shore-dwelling tourism with its associated infrastructures. These factors are adversely impacting the coastal and marine nature and the traditional socio-economic systems. The Zanzibar government has put forward several initiatives to protect the health of the coastal ecosystems and the endurance of the traditional cultures. The effective implementation of measures, for example, the Zanzibar Coastal and Marine Spatial Planning as part of the National Land Use Plan, have not yet been sufficient to restore the situation. However, there are also signs of commitment being fostered and an improvement in the know-how for making changes. We conclude by asserting the need for coastal and marine spatial planning as the holistic and robust approach for sustainable coastal and marine planning while emphasizing community participation throughout the process. [ABSTRACT FROM AUTHOR]

The present study proposes a diagnosis of the conditions and impacts on estuarine beaches of the Amazonian coast based on the application of the DPSIR (Driving Forces, Pressures, State, Impact, Responses) model, which identifies the natural and anthropogenic drivers affecting the environment. Natural drivers are related primarily to the accentuated hydrodynamic processes, high rainfall and fluvial discharge. The anthropogenic driver is related to the lack of planning for beach development. These human pressures result in a reduction in the quality of the beaches through microbiological contamination, the accumulation of garbage on the sand and in the water, sewage outfalls, and overcrowding which, combined with the intense local hydrodynamics and the lack of planning of recreational activities (zoning, warning signs, lifeguard coverage) may increase the risk of accidents for beachgoers, such as drowning, and injuries caused by motorboats, jet skis and stingrays. Despite all the problems identified, no response whatsoever was observed from the local authorities. The results of the DPSIR analysis indicate an urgent need for the implementation of beach management plans to improve the conditions of the beaches and in particular their safety, as well as identifying the obligations of the local authorities responsible for the future development of the Amazon coast. [ABSTRACT FROM AUTHOR]

Coastal zones can be considered inherently vulnerable because of sensitive ecosystems, geomorphological dynamics and complexity, and the clustering of many social, economic, and sometimes conflicting activities. In urban areas where tourism is highly treasured, this vulnerability is even worse. Intense demographic pressure may overload the carrying capacity limits of the sensitive coastal ecosystems. This process also exposes the population living in risky areas to physical vulnerability. This paper aims to present a methodology to integrate the physical, socioeconomic and ecosystem dimensions of coastal vulnerability through a useful tool for coastal zone management. It is propose a matrix that allows correlating the exposition degree and adaptive capacity of vulnerability. Based on this matrix it is possible to plot the integrated coastal vulnerability into a diagram of integrated coastal vulnerability assessment (DICVA). The case study of Região dos Lagos presented in this paper uses this integrated approach of coastal vulnerability. Between 2000 and 2010, the urban population grew significantly on the coast subject to erosion and tidal flood, as well as in flood-prone areas around the lagoons. In many cities, a massive influx of tourists surpasses the number of urban residents causing a deficiency in the water and sewage utilities systems. A resulting problem is the risk of groundwater contamination and lagoons pollution. These impacts can backfire and negatively impact the tourism industry as the environmental quality declines and the risk sensation increases. The proposed, integrated, and updated approach to coastal vulnerability may help to understand the complex effects of the relationship found in the different dimensions involved. Furthermore, this approach contributes to the effective use of the matrix and Diagram of Integrated Coastal Vulnerability Assessment, and may guide coastal management actions. [ABSTRACT FROM AUTHOR]

The extreme predictions of the Intergovernmental Panel on Climate Change (IPCC) have been the inspiration of hundreds of papers by local panels proposing ever-increasing alarming messages. The latest analyses are on the effect on the surf spots of California of a tidal range added to a sea level rise of 1.67 m. We show that the sea level rises estimate by a local panel for California as well as the IPCC for the entire world are up to one order of magnitude larger than what is extrapolated from present sea level rise rates and accelerations based on tide gauge data sets (California-8, Permanent Service on Mean Sea Level PSMSL-301, Mitrovica-23, Holgate-9, National Oceanic and Atmospheric Administration NOAA-199 and US-71). These extrapolations are consistent with present temperature warming rates and accelerations of different global temperature data sets (University of Alabama in Huntsville UAH and Remote Sensing Systems RSS) and IPCC Assessment Report (AR) 5 Representative Concentration Pathway (RCP) 8.5 sensitivity. As the evidence from the measurements does not support the IPCC expectations or the even more alarming predictions by the local California panel, these claims and the subsequent analyses are too speculative and not suitable for rigorous use in planning or policy making. [ABSTRACT FROM AUTHOR]

We conduct a risk assesment of losses to coastal properties due to tropical storms in The Bahamas. To this end we use the physical characteristics of a set of synthetically generated storms to estimate local wind and storm surge exposure and couple with these damage functions. Employing these to a unique set of properties on the island of Great Exuma we then calculate out likely losses, in terms of loss of real estate value as well as potential income, due to the storms. Our analysis suggests that while annual expected losses are small, this disguises low probability storms that could cause considerable damage. Moreover, we find that most of the losses are due to storm surge rather than strong winds. This may be particularly important for low-lying islands like The Bahamas facing future challenges of sea-level rise. [ABSTRACT FROM AUTHOR]

Changes to mean sea level and/or sea level extremes (e.g., storm surges) will lead to changes in coastal impacts. These changes represent a changing exposure or risk to our society. Here, we present 21st century sea-level projections for Norway largely based on the Fifth Assessment Report from the Intergovernmental Panel for Climate Change (IPCC AR5). An important component of past and present sea-level change in Norway is glacial isostatic adjustment. We therefore pay special attention to vertical land motion, which is constrained using new geodetic observations with improved spatial coverage and accuracies, and modelling work. Projected ensemble mean 21st century relative sea-level changes for Norway are, depending on location, from -0.10 to 0.30 m for emission scenario RCP2.6; 0.00 to 0.35 m for RCP 4.5; and 0.15 to 0.55 m for RCP8.5. For all RCPs, the projected ensemble mean indicates that the vast majority of the Norwegian coast will experience a rise in sea level. Norway's official return heights for extreme sea levels are estimated using the average conditional exceedance rate (ACER) method. We adapt an approach for calculating sea level allowances for use with the ACER method. All the allowances calculated give values above the projected ensemble mean Relative Sea Level (RSL) rise, i.e., to preserve the likelihood of flooding from extreme sea levels, a height increase above the most likely RSL rise should be used in planning. We also show that the likelihood of exceeding present-day return heights will dramatically increase with sea-level rise. [ABSTRACT FROM AUTHOR]

A source-pathway-receptor method is used to assess the risk of the coastal community of Charlestown, RI, USA, to the 100-year storm, including effects of sea level rise (SLR) and shoreline/dune erosion. The 100-year storm is simulated using a chain of stochastic and physics-based models combined with a scenario-based approach. Storm surge and wave spectral parameters, obtained from the U.S. Army Corps of Engineers' North Atlantic Coast Comprehensive Study (NACCS), are used as boundary conditions for high-resolution wave simulations, performed in the coastal and inundation zones using the steady-state spectral wave model STWAVE. Selected scenarios are defined to assess the magnitude of the variability in predicted damage resulting from the uncertainty in SLR, erosion rate, and time at which the 100-year storm would occur. Erosion rates are based on empirical analyses of historic rates of shoreline change, SLR measurements, and coastal erosion theory. The risk is measured in terms of damage to individual houses, based on damage curves developed in the U.S. Army Corps of Engineers, NACCS study. In addition, remediation scenarios are explored, demonstrating that a combination of dune replenishment and an increase in the residential resilience by elevating structures can significantly diminish the risk to the coastal community. [ABSTRACT FROM AUTHOR]

Paleo relative sea-level (RSL) indicators formed during the Marine Isotope Stage (MIS) 5e have been reported by a large number of studies worldwide. Despite this, three main aspects are seldom reported: (1) use of high-precision survey techniques applied to MIS 5e RSL indicators; (2) application of modern analogs to understand the indicative meaning of MIS 5e RSL indicators; (3) estimates of the effects of glacial isostatic adjustment (GIA) on the MIS 5e records. In this study, we show how the three points above have been addressed in a focused study on Last Interglacial outcrops on the island of Mallorca. We measured the elevation of several RSL indicators with high-accuracy differential GPS (vertical accuracies down to 0.1 m) and we established the relationship between each RSL indicator and the paleo sea level through calculation of the indicative meaning for each RSL indicator. In particular, we present a novel technique to calculate the indicative meaning of fossil beach deposits with a phase-averaged morphodynamic model (CSHORE). We show how this approach helps overcoming difficulties with the survey of the modern analogs for these indicators. Our results show that two paleo RSLs are imprinted in Mallorca at + 2.9 ± 0.8 m and + 11.3 ± 1.0 m. We then compare our field-based results with modelled paleo RSL, calculated from the predictions of the ice-earth coupled ANICE-SELEN model, using few different ice-sheet melting scenarios during MIS 5e. We conclude that indicative ranges can be derived from relatively simple morphodynamic models and that the comparison of field-derived and modelled RSL values is a good method to validate possible scenarios of MIS 5e sea-level variability, especially in absence of precise dating. [ABSTRACT FROM AUTHOR]

Submerged shorelines hold much potential for examining the interplay between the rate of sea-level rise and geomorphic setting, and informing the development of models of contemporary shoreline behavior. This paper describes the sedimentary architecture of a submerged barrier shoreline complex off Durban, South Africa. The complex consists of several barriers that have survived the postglacial transgression and associated erosive ravinement processes. The main shoreline sequence (-60 m) dates to 11,690 ± 90 calibrated (cal) yr B.P. and rests on a Pleistocene lagoonal deposit (35,395 ± 592 cal yr B.P.). The entire barrier shoreline complex is truncated by a strongly diachronous wave ravinement surface. The ravinement surface seaward of the main -60 m shoreline is steep, but the gradient declines across and landward of the subordinate landward shoreline complexes. The steep ravinement surface is attributed to fast sea-level rise (possibly associated with meltwater pulse 1B), while the gentle ravinement surface is associated with a subsequent slowing of the rate of sea-level rise (to 0.15 mm yr-1). Preservation of the main barrier and backbarrier deposits through overstepping is associated namely with rapid transgression and increased back-barrier accommodation. The smaller barriers landward of the main barrier were preserved through overstepping related to gentle antecedent gradients, despite more intense ravinement during a very slow rise in sea level (slowstand). This process was assisted by a sediment deficit. The resulting post-transgressive drape is also influenced by antecedent topography created by the barriers themselves; damming along the landward sides of overstepped barriers thickens the drape and creates a temporal disconnect between the migration of the shoreface and more landward elements of the littoral system. In examining the rates of shoreline migration associated with the overstepped barrier system, these are far greater than those calculated for the predicted rates of shoreline change on similarly steep coastal profiles. Future rates of shoreline migration appear to be insufficient to cause overstepping, and rollover or erosional responses are more likely. [ABSTRACT FROM AUTHOR]

ABSTRACT This study compares observations of 22 climate variables [rainfall, minimum and maximum temperature, mean sea level pressure (MSLP), and air temperature, geopotential heights, relative and specific humidity, and u-wind and v-winds at 500, 700 and 850 hPa] over Australia with NCEP-NCAR (National Centers for Environmental Prediction-National Center for Atmospheric Research) and ERA-Interim, two most often used reanalysis products. The results indicate that both NCEP-NCAR and ERA-Interim generally reproduce the observed spatial patterns of long-term mean annual rainfall, daily maximum/minimum temperature and MSLP, the monthly distribution (annual cycle) of rainfall and temperature, although temperature is generally better simulated than rainfall and ERA-Interim shows an overall better performance than NCEP-NCAR in term of continental scale. In term of linear trends, both NCEP-NCAR and ERA-Interim simulate observed trend signs in some regions, but not in others, and the spatial distributions of temperature trends are generally not as well simulated as that of annual rainfall for both NCEP-NCAR and ERA-Interim. In addition, NCEP-NCAR and ERA-Interim show similar spatial patterns of annual mean air temperature, geopotential heights, humidity and winds. This implies that studies using NCEP-NCAR data could also make use of ERA-Interim to explore the range of uncertainties for the regions and climate variables where NCEP-NCAR and ERA-Interim show differences. This conclusion may also apply to regions other than Australia. For example, the different trend signs of MSLP between NCEP-NCAR and ERA-Interim could present a scientific challenging for climatic change studies using MSLP trends, and the split between large-scale and convective rainfall would also have merits globally to understand if the differences between the two reanalysis data sets are global or if we see convergence on key areas, such as tropices and frontal systems. [ABSTRACT FROM AUTHOR]

Coastal communities have been repeatedly threatened by the ephemeral character of the coast. Morphological changes derived from climate events and sea level oscillations forced the relocation of coastal communities over the past, but never prevented the occupation of this fragile source of wealth. Moreover, the socio-economic impact of high energy events is dramatically increasing due to the growing occupation of the coast, raising the need for rethinking the way disaster risk reduction measures are implemented to ensure effectiveness and acceptance. To illustrate this conflict (occupation versus risk), we explore risk perception in a population located in a fragile segment of the southern coast of Portugal, Praia de Faro, in order to identify the factors shaping risk perception and to understand the reasons behind the occupation of risky coastal areas. The selected community consists of two different populations (a fishermen community and a tourism-related community) sharing the risk associated with storm impacts and coastal retreat. For that, we examine the socio-economic and environmental frameworks and run a set of in depth interviews to provide a frame for understanding the culture of risk in a system with multiple stakeholders and planned measures of relocation. Interviews in Praia de Faro suggest that citizens using the beach as their first residence have voluntarily accepted to live with risk in the beach in exchange for a series of related benefits that they find to largely exceed expected personal damages. Risk perception analysis found that the community is aware about the hazards impacting the area, but they are not worried or prepared to face likely levels of risk derived from the impact of storms estimated by experts. Characteristics of risk perception seem shaped by place attachment, underestimation of impact probability and lessons learnt, and inherent cultural aspects. In addition, it seems clear that imposed measures of relocation are contributing to reduce residents risk perception in an attempt to ensure their permanence in the area in a frame of institutional distrust and absence of genuine communication. Alternative measures to relocation can only exist if responsibilities in risk mitigation are reconsidered and shared. [ABSTRACT FROM AUTHOR]

With the global rise in sea levels caused by climate change and frequent extreme weather processes, high-density population aggregation and human development activities to enhance coastal areas vulnerability, populations, resources, and the ecological environment are facing huge pressure. Natural coastlines are being destroyed, and increasingly serious problems, such as coastal erosion and ecological fragility, have become disasters in coastal zones. The coastal vulnerability changed by climatic variables has created a major concern at regional, national and global scales. By comparing the data of two periods in the past 40 years, coastline vulnerability of coastal erosion in mainland China were evaluated by use of reverse cloud model and AHP with 10 indicators, including natural, anthropogenic, social and economic factors, etc. The main factors controlling coastal erosion included the proportion of Quaternary strata, the gradual reclamation of marine areas as land areas (in kilometres) and the percentage decrease in coastal sediment entering the sea. The secondary impact factors included the high proportion of artificial coastlines and the impacts of waves and storm surges under the influence of relative sea level changes. Human activities could further influence coastal vulnerability, making the erosion risk a considerable concern. Legislation, coordinated management system and technology are proposed to improve the quality of the marine ecological environment. [Display omitted] • The main factors controlling coastal erosion of mainland China were changed greatly in 1984–1995 and 2008 to 2017. • The degree to which human activities influence coastal vulnerability and erosion risk of mainland China is revealed in the past 40 years' high speed economic development. • The cloud model is used to objectively evaluate the coastal erosion vulnerability in China. [ABSTRACT FROM AUTHOR]

Peak eustatic sea level (ESL), or minimum ice volume, during the protracted marine isotope stage 11 (MIS11) interglacial at ~420 ka remains a matter of contention. A recent study of high-stand markers of MIS11 age from the tectonically stable southern coast of South Africa estimated a peak ESL of 13 m. The present study refines this estimate by taking into account both the uncertainty in the correction for glacial isostatic adjustment (GIA) and the geographic variability of sea level change following polar ice sheet collapse. In regard to the latter, the authors demonstrate, using gravitationally self-consistent numerical predictions of postglacial sea level change, that rapid melting from any of the three major polar ice sheets (West Antarctic, Greenland, or East Antarctic) will lead to a local sea level rise in southern South Africa that is 15%-20% higher than the eustatic sea level rise associated with the ice sheet collapse. Taking this amplification and a range of possible GIA corrections into account and assuming that the tectonic correction applied in the earlier study is correct, the authors revise downward the estimate of peak ESL during MIS11 to 8-11.5 m. [ABSTRACT FROM AUTHOR]

Shell middens are conspicuous manifestations of the exploitation of rich, sustainable, easily seen and harvested marine resources that, worldwide, enabled hunter-gatherers to reduce mobility and increase population and social complexity. Globally, known sites tend to cluster chronologically around 6 k BP, after slowing eustatic sea-level rise, although the Pacific coast of South America offers some rare earlier exceptions. We report investigations of La Yerba II, a Middle Preceramic shell matrix site on the Río Ica estuary, south coast Peru. These show how, beginning around 7000 Cal BP, over 4.5 m of stratigraphy accumulated in less than 500 years. Consisting of prepared surfaces, indurated floors and the ashy interiors of wind shelters and their associated midden deposits, alternating with phases of abandonment, this was the outcome of an intense rhythm of repeated occupations by logistically mobile marine hunter-gatherers. Final phases, dominated by Mesodesma surf clams, mark change towards more task-specific activities. La Yerba II's topographic position and well-preserved cultural and environmental markers provide insight into the local history of relative sea level change and changing marine hunter-gatherer lifestyles during a period critical to the transition to sedentism and the formation of new estuarine and beach habitats following the stabilisation of eustatic sea-levels. • We investigate La Yerba II a large shell midden on the Río Ica estuary, south coast Peru. • We show how, beginning around 7000 BP, over 4.5 m of midden stratigraphy accumulated in less than 500 years. • These consist of prepared floors, ashy wind shelter interiors and middens, alternating with phases of abandonment. • They are the outcome of an intense rhythm of repeated occupations by logistically mobile marine hunter-gatherers. • La Yerba II's position today also documents relative sea level change through on-going tectonic uplift along this coast. [ABSTRACT FROM AUTHOR]

The coastline of Indonesia, which borders almost 17,500 islands and the sea and extends for more than 80,000 km, is vulnerable to sea level rise. This paper aims to investigate the impact of sea level rise on coastal ecology in Indonesia focusing on coastal area of Jakarta, Pekalongan, Semarang and Demak in the northern part of Java Island. Geo-spatial data, i.e. satellite images and maps were used to monitor the environmental changes and primary data were obtained through field survey and observation on the specified area. In Jakarta, sea level rise has been predicted to bring great damages to infrastructure in coastal area. Multiple impacts of sea level rise towards mangrove, agriculture, and aquaculture ecosystem occurs in Pekalongan. Semarang coastal area also suffers from the widening spread of health problems as the coastal inundation increases. At the same time, Demak experiences major losses on mangrove and aquaculture ecosystem due to sea level rise. [ABSTRACT FROM AUTHOR]

A depositional model for the development of the Helvetiafjellet Formation in Nordenskiöld Land, Spitsbergen is presented. The formation was deposited into a segment of the large epicontinental Boreal basin that rimmed northern Pangaea during the Early Cretaceous. A wide range of depositional subenvironments are recorded within the succession; including fluvial braidplain, shallow marine bay, delta, coastal plain and fluvial channel. The depositional model approaches a layer-cake style for this part of the basin, caused by the rapid rates of progradation and retrogradation made possible by the gentle depositional gradient. An initial period of fluvial deposition arose in response to an early rise in relative sea-level. Following a regional flooding, the progradational to aggradational architecture in the area reflects a balanced rate of increase in accommodation vs. rate of sedimentation (A/S) ratio. This resulted in a heterolithic stacking of sandstone and mudstone. Autogenic variables are thought to have dominated the lateral facies variations recorded in the upper and middle parts of the succession. [ABSTRACT FROM AUTHOR]

The coastal strip between the Volta River delta and the westernmost portion of Benin (West Africa Margin of Atlantic Basin) is highly populated (e.g., Lomé) due to migrations from inland areas. The coastal zone has proved to be very vulnerable because of the potential development of sometimes catastrophic events related to different and interacting causes, resulting in negative effects on natural ecosystems and socio-economic conditions. The main problem is the marked erosion of large coastal sectors with maximum retreat rates of the order of 5 m/year. The continuous loss of territory leads to a progressive impoverishment of activities and human resources and to the increase of geological risk factors. The coastal erosion is induced both by natural and anthropic causes and can be controlled only by means of prevention programs, detailed scientific studies and targeted technical interventions. The main erosional processes observed in the study area are triggered by the presence of the Lomé port and other human activities on the coastal strip, including the water extraction from the subsoil, which induces subsidence and the use of sediments as inert material. These elements, together with the reduction of the solid supply from Volta River (caused by the realization of the Akosombo dam) are among the main factors that control the medium and long-term evolution of the area. Also relative sea level changes, which take into account also tectonic and/or isostatic components, can contribute to the process. In order to have a real understanding of the coastal dynamics and evolution, it would be necessary to develop a scientific structure through the collaboration of all countries of the Bight of Benin affected by coastal erosion. The aim should be primarily to collect the interdisciplinary quantitative data necessary to develop a scientific knowledge background of the Bight of Benin coastal/ocean system. In conclusion, some proposals are presented to reduce the vulnerability of the coastal area as for example to plan surveys for the realization of appropriate coastal protection works, such as walls, revetments, groins, etc. A possible expansion of the port of Lomè is also considered. Proposals comprise the constitution of a Supranational Scientific Committee as a coordinating structure on erosion for both the study of phenomena and planning interventions. [ABSTRACT FROM AUTHOR]

Hart, D.E.; Pitman, S.J., and Byun, D.-S., 2020. Earthquakes, coasts and climate change? Multi-hazard opportunities, challenges and approaches for coastal cities. In: Malvárez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 819–823. Coconut Creek (Florida), ISSN 0749-0208. Aotearoa New Zealand (ANZ) experienced several major earthquake disruptions to coastal environments between 2010 and 2016, including to the natural and built environment components of coastal cities and rural centers. Key places affected included Ōtautahi Christchurch city and the town of Kaikōura. Lessons learned about coastal environment/ earthquake interactions are useful in transforming our approach to adapting to climate change in coastal settlements. This paper reviews highlights of the temporary and lasting effects of the recent ANZ 'coastal quake' events in sand beach, mixed sand and gravel beach, estuary, delta and lagoon settings. Key topics include sediment budgets and beach states, estuary stability, ecosystem translation and squeeze, liquefaction, and effects of relative sea level change. Findings include the potential robustness of open coast beach systems to both uplift and subsidence, the relative sensitivity of estuarine and delta city hydraulics and ecosystem resilience once built environment boundaries and interactions are considered, and the potential for coastal hazard interactions and cascades with both negative and positive consequences. Analysis of these earthquake events can be used, not only to 'build back better', but also to underpin a shift in approaches to coastal hazards and climate change challenges, via a multi-hazards perspective. [ABSTRACT FROM AUTHOR]

This research aims to evaluate the amount of vertical ground movements during Roman times inside the archaeological area of Portus Julius (Gulf of Pozzuoli) using high-precision surveys on the most reliable archaeological sea-level markers. Measuring the submersion of ancient floors, structural elements belonging to a former fish tank, and several roman pilae, two different relative sea levels (RSLs), related to the beginning and the end of the first century BCE, respectively, −4.7/−5.20 m and −3.10 m MSL (mean sea level), were detected. A photogrammetric survey was carried out in order to produce a 3D model of the fish tank. The results in terms of the RSL variations have enabled us to reconstruct a morpho-evolution of the ancient coastal sector during the last 2.1 kyBP. At the beginning of the first century BCE, the area was characterized by a sheltered gulf with numerous maritime villae located along the coast. In 37 BCE, the construction of the military harbour of Portus Julius strongly modified the paleogeography of the sector, which was also affected by a prevailing subsidence at least until the end of the first century BCE (year 12 BCE), when the port was converted into a commercial hub. [ABSTRACT FROM AUTHOR]

Volcanic ocean islands offer a unique opportunity to quantify the influence of wave power on seacliff retreat rates because they typically have homogeneous bedrock, well-constrained initial topography, and dramatic gradients in wave power where their curving shorelines face different wave regimes. Here, we examine the influence of wave power on 10⁴- to 10⁶-year sea cliff retreat rates in the Hawaiian Islands. We model the transient evolution of 13 bedrock coastal profiles on the Big Island of Hawai'i, Maui, and Kaho'olawe over their 12 kyr to 1.4 Myr histories, assuming a constant cliff retreat rate and removal of all rock undercut by cliff incision. Since relative sea level change influences the amount of time that coastal erosion occurs at the primary cliff face over these long time periods, we use geophysical modeling and oxygen isotope records to estimate possible sea level histories at each site. We then test a range of cliff retreat rates and relative sea level histories simultaneously to find the best-fit cliff retreat rate at each site and the best-fit relative sea level history to all sites. We find a best-fit relative sea level history consistent with an effective elastic thickness of the lithosphere of 30 km, similar to previous estimates, and relatively steady deflection due to loading over the growth period of a Hawaiian volcano. Cliff retreat rates estimated from our long-term modeling of coastal profile development under changing sea level are systematically higher than rates estimated directly from the width of wave-cut platforms. Using 30-year hindcast wave data, we find positive linear relationships between the best-fit seacliff retreat rates and both mean annual wave power and one-year recurrence interval wave power at each site. These comparisons offer field evidence for a scaling between cliff retreat rates and wave power, providing an empirical basis for modeling bedrock coastal erosion over geologic timescales. [ABSTRACT FROM AUTHOR]

Scotland has a varied and dynamic coast, with up to 19% of the coastline classified as soft and potentially erodible. These areas face an increased risk of coastal erosion and coastal flooding, driven by observed sea level rise that is predicted to accelerate and by changing frequency and intensity of extreme weather events. Historic rates of coastal change have now been quantified along the Scottish coast, and key socioeconomic assets at risk from future coastal erosion have been identified. While coastal evolution is complex and challenging to predict, there is an ever-increasing desire for robust models capable of quantifying coastal change over a range of timescales and scenarios. We aim here to make quantitative predictions of future coastal erosion and its uncertainty at several key sites in Scotland identified as the most economically and environmentally vulnerable. We adapted the Coastal One-line Assimilated Simulation Tool (CoSMoS-COAST) (Vitousek et al., 2017) to model the evolution of these coastal sites under scenarios presented by UK Climate Projections 2018 (UKCP18). The model uses a process-based approach to simulate shoreline change via wave-driven alongshore and cross-shore sediment transport processes, but also long-term shoreline migration driven by sea-level rise. Variations in modelled beach type (from fine sand sections to armoured and artificial coast fronts) allow for both greater complexity in the simulated processes and investigation into the extent of human influence on shoreline change. The model is calibrated by assimilating historic records of mean high water spring positions spanning the 20th Century and local records of relative sea level change and wave hindcast data. This is validated with recent shoreline position observations derived from high-resolution topographic surveys and satellite and aerial imagery. Shoreline change is then simulated to the year 2100 under low to high Representative Concentration Pathway scenarios within UKCP18, encompassing factors such as the intensification and proliferation of sea level rise and storm surge activity. We report anticipated future coastal erosion in Scotland at a diverse selection of sites where important coastal assets (e.g. transport infrastructure, tourism and cultural heritage) are at direct risk. Producing coastal change predictions for a range of coastal types and climate situations can then enable more accurate risk assessment and guide resilience and adaptation of Scotland's most vulnerable coastal areas. [ABSTRACT FROM AUTHOR]

A reply to a letter to the editor on their article about "Large long-term sea level projections do not mean giving up on coastal cities" is presented.