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Municipal bond markets began pricing sea-level rise (SLR) exposure risk in 2013, coinciding with upward revisions to worst-case SLR projections and accompanying uncertainty around these projections. The effect is larger for long-maturity bonds and not solely driven by near-term flood risk. We use a structural model of credit risk to quantify the implied economic impact and distinguish between the effects of underlying asset values and of uncertainty. The SLR exposure premium exhibits a trend different from house prices and is unaffected by house price controls. Together, our results highlight the importance of climate uncertainty in driving municipal bond prices. Authors have furnished an Internet Appendix , which is available on the Oxford University Press Web site next to the link to the final published paper online [ABSTRACT FROM AUTHOR]

Griggs, G., 2024. Can we make coastal communities resilient to sea-level rise? Journal of Coastal Research, 40(3), 571–576. Charlotte (North Carolina), ISSN 0749-0208. "Resilient" is a term that has gotten increasingly widespread usage in recent years as a solution or response for coastal communities to the well-documented global rise in sea level. The message that is usually conveyed seems to be that if we can make coastal communities resilient, everything will be fine and we will have solved the challenge of how to adapt to a rising sea. The federal government and some coastal state government agencies are providing grant money to encourage coastal communities to develop plans to become more resilient. This is an appropriate time to ask what would a resilient coastal community look like and can we actually make a community resilient to future sea-level rise, and if so, for how long? [ABSTRACT FROM AUTHOR]

Skinner, W.K., 2024. Coastal hazard assessment from multidecadal profile response incorporating climate patterns and sea-level rise. Journal of Coastal Research, 40(3), 511–526. Charlotte (North Carolina), ISSN 0749-0208. A new method for coastal hazard assessment is described and demonstrated by reference to a 40-year cross-shore profile record in Papamoa, New Zealand. It is based on a mathematical interpretation of the envelope within which long-term historic cross-shore profiles vary and from which, for the required assessment period, the statistically significant fully accreted-state and fully eroded-state profiles can be determined. The Monte Carlo method is used to derive stochastic outcomes for long-term trend (LTT) and sea-level rise (SLR) on the basis of correlations with, and a long term proxy for, a decadal-scale climate pattern, which in the example case is the Interdecadal Pacific Oscillation. Sediment volumes for short-term fluctuation and the LTT are determined and conserved to reflect a consistent wave climate over the assessment period when appraising the effect of SLR. Dune biomass is accounted for when determining erosion scarp stability and hence the final extent of the current and future hazard zones. Results are presented in schematic form as excursions relative to a land benchmark and also as full end-state profiles extending from the dune backshore to the closure depth, with the latter determined by bar volume and profile. Various scenarios are appraised, including those that incorporate SLR predictions of the climate models of the Intergovernmental Panel on Climate Change. The relative risk of various scenarios is benchmarked to the probalistic expected outcome to produce a risk-based, site-specific assessment of coastal hazards. [ABSTRACT FROM AUTHOR]

Aim: Glacial refugia are areas of primary importance for the evolution and conservation of biodiversity. Yet, their geographic location remains loosely defined even in intensively studied areas, preventing a thorough understanding of their role in the spatiotemporal biodiversity dynamics. With this study, we aim to locate the major glacial refugia within the biodiversity hotspot of the Italian peninsula, to understand the processes that warranted the long‐term persistence of biodiversity in the face of climate changes. Location: Italian peninsula. Taxon: Terrestrial vertebrates. Methods: We calibrated species distribution models (SDM) for 22 lineages of terrestrial vertebrates endemic to the Italian peninsula and projected the SDMs to the last‐glacial maximum conditions. Then, we combined single‐lineage projections to investigate the location and spatiotemporal dynamics of multi‐species glacial refugia. Results: Multi‐species refugia were mostly found in coastal areas that have been flooded by the post‐glacial marine transgressions, and that are currently below the sea level. Indeed, we identified six major areas acting as glacial refugia, mainly located outside the current coastline in the southern part of the peninsula and along the western coast. These areas were close to previously inferred locations of glacial refugia and genetic diversity hotspots, but none coincided with them. Conclusions: Results from this study outline glacial refugia as highly dynamic units. Most of the identified refugial areas have been lost by post‐glacial sea‐level rise. Accordingly, species persistence through the Late Pleistocene was not granted by long‐term environmental stability, but by the opportunity to shift species' distributions along altitudinal gradients, following changes in climate and habitat suitability. Notably, our results decouple glacial refugia from hotspots of genetic diversity. Thus, the current location of a hotspot should not be taken as evidence for the occurrence of a glacial refugium in that location—even though a refugium is likely to be located somewhere nearby. [ABSTRACT FROM AUTHOR]

China’s massive wave of urbanization may be threatened by land subsidence. Using a spaceborne synthetic aperture radar interferometry technique, we provided a systematic assessment of land subsidence in all of China’s major cities from 2015 to 2022. Of the examined urban lands, 45% are subsiding faster than 3 millimeters per year, and 16% are subsiding faster than 10 millimeters per year, affecting 29 and 7% of the urban population, respectively. The subsidence appears to be associated with a range of factors such as groundwater withdrawal and the weight of buildings. By 2120, 22 to 26% of China’s coastal lands will have a relative elevation lower than sea level, hosting 9 to 11% of the coastal population, because of the combined effect of city subsidence and sea-level rise. Our results underscore the necessity of enhancing protective measures to mitigate potential damages from subsidence. [ABSTRACT FROM AUTHOR]

Expansive soils pose a significant challenge in geotechnical engineering, especially in coastal areas. While research has mainly focused on their elastic properties, this study explores the overlooked aspect of inelastic subsidence during prolonged droughts, utilizing decade‐long GPS datasets from the University of Houston Coastal Center. Our findings reveal substantial subsidence, approximately one to two dm, during the summer droughts of 2018, 2020, 2022, and 2023, due to compaction within the upper 4 m of expansive soils. Inelastic subsidence constitutes roughly 10% of the total subsidence, resulting in step‐like permanent land elevation loss over time. Notably, drought‐induced subsidence is prominent in open‐field areas with expansive soils but is minor in built‐up areas or in non‐expansive soil regions. The occurrence of inelastic subsidence challenges traditional assessments of relative sea‐level rise and coastal flooding, emphasizing the need to consider it in coastal infrastructure planning for enhanced resilience against climate uncertainties. Plain Language Summary: Expansive soils, often found in coastal regions, are known for causing issues like land shifts and unstable buildings. Our research adds a new dimension: prolonged droughts can lead to significant, irreversible sinking of expansive soils, permanently lowering the elevation of open land areas. Using a decade of GPS data, we found that during droughts, these soils can sink considerably and will not fully recover. Interestingly, in developed regions where pavement covers the soils, thereby minimizing moisture loss, this sinking is observed to be minimal. In the Galveston coastal area, drought‐induced sinking can reach one to two dm, with irreversible subsidence making up about 10% of the total subsidence. This becomes a growing concern as droughts become more frequent due to climate change, especially in coastal areas. Additionally, our results suggest that current methods for estimating sea‐level rise may be missing a key factor: we have underestimated the speed at which uninhabited coastal lands are sinking because we did not account for this irreversible sinking due to droughts. Key Points: Prolonged droughts cause up 2 dm of subsidence in shallow expansive soils (<4 m deep) in Galveston, TX, 10% of which is inelasticProlonged droughts lead to notable subsidence in open fields with expansive soils, but less in built‐up areas or non‐expansive soil areasRecurring droughts lead to permanent land elevation losses in open‐field coast, possibly skewing sea‐level rise and flood risk projections [ABSTRACT FROM AUTHOR]

The Devonian System in the Qinghai-Tibetan Plateau and its surrounding areas is widely distributed, diverse in lithotypes and rich in fossils. It records the crucial processes of continuous subduction and reduction of the Paleo-Asian Ocean in the northern hemisphere and the transformation of the Proto-Tethys Ocean into the Paleo-Tethys Ocean in the southern hemisphere. Thus, it is of great significance for explaining the global paleogeographic evolution, tectonic activities and biodiversity changes during this critical period. The blocks on both sides of the southern Tienshan suture zone and the Longmu Co-Shuanghu-Changning-Menglian suture zone belong to different sedimentary systems and paleobiogeographic realms and regions, showing important tectonic paleogeographic partitioning significance. The two suture zones represent the main branches of the Paleo-Asian Ocean and the Paleo-Tethys Ocean, respectively, and on this basis the Devonian System can be subdivided into three types: the Tienshan type, the Tethys type and the Gondwana type. Based on recent research progress on the Devonian stratigraphy and paleontology in combining provenance analysis and biotic characteristics in the Qinghai-Tibetan Plateau and surrounding areas, this paper aims to establish the latest integrative stratigraphic framework and conduct paleogeographic reconstruction, providing foundation for exploring the geological evolution and dynamic mechanisms of various terranes and blocks in the northern margin of Gondwana. The results indicate that the North Qiangtang, South Qiangtang, Simao, Baoshan and Tengchong terranes, as well as the Himalaya Tethys Zone and the South China Block have affinities with the Indian Block, while the Lhasa Terrane has affinities with the Australian Block, and may be located between the South China and Australian blocks. In the Emsian (Early Devonian), the South China Block separated from the northern margin of Gondwana, a process that was accompanied by the opening of the Jinshajiang-Ailaoshan Ocean. In the Middle Devonian, the mid-oceanic ridge of the Paleo-Tethys Ocean expanded rapidly, corresponding with a global sea-level rise, the widespread development of carbonate platforms and nadir values of Devonian seawater strontium isotopes. By the Late Devonian, the Paleo-Tethys Ocean had reached a considerable size, leading to abundant occurrences of Upper Devonian radiolarian cherts in the Paleo-Tethys suture zones. [ABSTRACT FROM AUTHOR]

This document is a discussion of the original paper titled "Coastal Defense Megaprojects in an Era of Sea-Level Rise: Politically Feasible Strategies or Army Corps Fantasies?" by D. J. Rasmussen, Robert E. Kopp, and Michael Oppenheimer. The authors review coastal defense megaprojects with storm surge barriers in the United States and discuss their feasibility. They compare the findings of the original paper with experiences from the implementation of coastal megaprojects in the Netherlands and identify key factors crucial for their feasibility and realization. The document concludes that coastal megaprojects with barriers are feasible and will be needed for future coastal protection and adaptation. [Extracted from the article]

The study area is located in cental Slovenia, and geologically located at the junction between the Alps and the Dinarides. The Middle Triassic of this region is characterised by intense rifting manifested by differential subsidence and volcanism. This led to a major paleogeographic reorganisation of the region, where three paleogeographic domains formed in the Upper Triassic: The Julian Carbonate Platform in the north, the intermediate Slovenian Basin, both parts of the Southern Alps, and the Dinaric (Adriatic, Friuli) Carbonate Platform in the south, which today is a part of the External Dinarides that host the area of investigation. Prior to the installation of the Dinaric Carbonate Platfrom, i.e. in the Ladinian, the entire area of the preset-day External Dinarides broke up into numerous tectonic blocks that were exposed to either erosion or continental, shallow-marine, and deep-marine sedimentation. In this study, we analyse at small scale a complex transitional area between a local carbonate platform and the Kobilji curek basin (depositional area dominated by deeper marine sediments), located in the Rute Plateau in central Slovenia south of Ljubljana. During enhanced subsidence, the basin was filled with volcanic material (tuffs and volcanogenic clays and subordinate extrusive material), while the adjacent platform aggraded. The slope was positioned above active paleofaults. During relative sea level lowstand, the platform prograded across the basin. The study area is divided into four major tectonic paleoblocks. The NW paleoblock experienced the most enhanced subsidence, and the platform prograded twice in this area and was submerged again by the rejuvenated subsidence and/or sea-level rise. The second and third paleoblocks subsided only during discrete major subsidence events, and the carbonates of the platform and slope were soon reinstated therein. In the fourth paleoblock to the east the platform persisted during the Ladinian. In the Carnian, the entire study area became emerged, and continental clastics were deposited. These were then replaced by a uniform shallow marine/intertidal Hauptdolomit (Dolomia Principale) formation at the onset of the Norian. This study provides the first detailed reconstruction of the sedimentary evolution of small-scale Ladinian basin and platforms system in the northern External Dinarides. [ABSTRACT FROM AUTHOR]

The purpose of this study was to prove the direct correlation of a successions of gravel‐clay beds recovered in borehole with the melt‐water pulses associated with the sea‐level oscillations indicated in the δ18O record in the time‐span preceding the 100‐kyr glacial cycles. Aimed at this scope, we provide combined 40Ar/39Ar and paleomagnetic constraints to a set of seven aggradational successions recovered from a 120 m deep borehole drilled in the buried Paleo‐Tiber delta in Rome (central Italy). The geochronologic constraints enable the correlation of each aggradational succession, characterized by a sudden transition from coarse gravel at the base to sandy clay sediments, with periods of sea‐level rise indicated by the δ18O curve encompassing MIS 37 through MIS 19, from 1250 to 780 ka. This stratigraphy, provides a unique and unprecedented well‐dated evidence of glacial/deglacial events, matching the global benthic δ18O stack during this time frame. Furthermore, this study validates the hypothesis that gravel deposition in the catchment basin and the delta of the main rivers in central Italy is triggered by the melting of glaciers in the Apennines Mountain range. It demonstrates the significant potential of these deglaciation proxies to be used worldwide to unravel the chronology of glacio‐eustatic events. Plain Language Summary: In this study, we used a combination of dating techniques and paleomagnetic data to examine a series of sediment layers found in a buried ancient river delta in Rome, Italy. These sediment layers were collected from a 120 m deep borehole. By analyzing the age of these sediment layers, we were able to link them to a period in the past when sea level was rising. This sea‐level rise occurred between 1250 and 780 ka, covering a range of time from MIS 37 to MIS 19. These sediment layers show a distinct change from coarse gravel to sandy clay, which provides valuable information about glacial and deglacial events. These findings support the idea that the deposition of gravel in river catchment areas and deltas in central Italy is linked to the melting of glaciers in the Apennines Mountain range. This research not only validates this hypothesis but also highlights the potential for using similar techniques globally to better understand the timing of glacio‐eustatic events. Key Points: We provide 40Ar/39Ar and paleomagnetic constraints to seven aggradational successions recovered from a 120 m deep borehole in RomeEach aggradational succession is correlated with a period of sea‐level rise encompassing MIS 37 through MIS 19, 1250 to 780 kaThis study shows that gravel deposition in the catchment basin of the main rivers in central Italy is a direct proxy of deglacial events [ABSTRACT FROM AUTHOR]

Tidal freshwaters in upper estuarine reaches provide important ecosystem services but are threatened by relative sea-level rise and pollution from increased development. Tidal freshwaters are highly productive and support estuarine and riparian food webs alike. Aquatic insects are common prey subsidies crossing into riparian habitats; however, the magnitude, timing, and composition of insect emergence in tidal systems has received little attention. Our objective was to better understand the magnitude and variability of aquatic insect emergence in tidal freshwaters. To do so, we quantified insect emergence from tidal creeks and estuarine shorelines of the James River Estuary, Virginia, USA, and characterized spatial and temporal patterns in the amount of emergent biomass. We continuously monitored insect emergence from 7 April to 8 November 2019 with floating emergence traps to estimate daily emergence, then used generalized additive mixed models to analyze spatial and temporal variation in daily emergence rates. We estimated aquatic insect biomass to emerge at a mean rate (±1 SE) of 15.6 ± 2.0 g dry mass m−2 y−1, which is among the highest of previously published estimates from nontidal systems (mean ±1 SE = 12.9 ± 6.2 g dry mass m−2 y−1). Spatial variability in emergence was highly taxon specific. Diptera and Trichoptera had more biomass emerging from the subtidal than intertidal zone, Odonata biomass emerged more from tidal creeks than along the estuarine shoreline, and the amount of Trichoptera biomass increased—whereas Ephemeroptera decreased—with distance from the estuarine shoreline. The magnitude and composition of emergent taxa varied throughout the sampling period, with sequential peaks in biomass that altered the prey available to riparian consumers. Our results suggest that tidal freshwaters export substantial quantities of aquatic insects, which are valuable prey items for riparian consumers in these systems. [ABSTRACT FROM AUTHOR]

Groundwater is present at shallow depth under many coastal low-lying cities. Despite the importance of protecting coastal urbanised areas from flooding and climate-change-induced sea-level rise, the effects of shallow groundwater fluctuations are rarely investigated. The aim of this study was to determine characteristics of shallow groundwater, including spatial and temporal trends in depths to groundwater and their relationship to natural and anthropogenic stressors. The study uses depth to groundwater measurements from a uniquely extensive and densely spaced monitoring network in Ōtautahi/Christchurch, New Zealand. Data-driven analysis approaches were applied, including spatial interpolation, autocorrelation, clustering, cross-correlation and trend analysis. These approaches are not commonly applied for groundwater assessments despite the potential for them to provide insights and information for city-wide systems. The comprehensive approach revealed discernible clusters and trends within the dataset. Responses to stresses such as rainfall events and stream flow were successfully classified using clustering analysis. The time series analysis indicated that in areas of shallow groundwater, low variation in levels occurred and this was also found using clustering. However, attributing some clusters to specific hydrogeological attributes or stressors posed challenges. The primary feature in hydrograph classification proved to be the proximity to tidal rivers and their correlation with tidal signals. These results highlight the value of using large datasets to characterise spatial and temporal variability of shallow groundwater in urban coastal settings and to assist with monitoring infrastructure planning in the face of future climate-change hazards. [ABSTRACT FROM AUTHOR]

The present work is an effort to expose the sedimentation rate of the Ganges–Brahmaputra (GB) tidal delta plain from the subsurface-dated sediments samples. The study reveals that the average sedimentation rates (about 2.12–4.59 mm yr−1) of the area are not as good to minimize as the estimated range of relative sea-level rise (RSLR) (1–9 mm yr−1). Moreover, the sediments cannot be distributed properly in the tidal and fluvio-tidal plains due to different anthropogenic activities like poldering and embankments. In addition, the upstream diversion of the Ganges and the Brahmaputra rivers water reduces the suspended sediment load to the downstream and consequently, the sedimentation rates. Finally, the GB tidal delta plain and its coastal area are in a vulnerable situation in consideration of sedimentation rates, RSLR, and different anthropogenic activities. Therefore, regular monitoring and evaluation is essential about sedimentation, coastal and upstream anthropogenic practices, RSLR, etc., for the implementation of effective and efficient mitigation and adaptation measures in the deltaic plains. [ABSTRACT FROM AUTHOR]

Coastal groundwater‐dependent ecosystems (GDEs), such as wetlands, estuaries and nearshore marine habitats, are biodiversity hotspots that provide valuable ecosystem services to society. However, coastal groundwater and associated ecosystems are under threat from groundwater exploitation and depletion, as well as climate change impacts from sea‐level rise and extreme flood and drought events. Despite many well‐intentioned policies focused on sustainable groundwater use and species protection, coastal GDEs are falling through gaps generated by siloed policies and as a result, are declining in extent and ecological function. This study summarized then examined policies related to the management of coastal groundwater and connected ecosystems in two key case study areas: Queensland (Australia) and California (USA). Despite both areas being regarded as having progressive groundwater policy, our analysis revealed three universal policy gaps, including (1) a lack of recognition of the underlying groundwater system, (2) fragmented policies and complex governance structures that limit coordination, and (3) inadequate guidance for coastal GDE management. Overall, our analysis revealed that coastal GDE conservation relied heavily on inclusion within protected areas or was motivated by species recovery, meaning supporting groundwater systems remained underprotected and outside the remit of conservation efforts. To close these gaps, we consider the adoption of ecosystem‐based management principles to foster integrated governance between disparate agencies and consider management tools that bridge traditional conservation realms. Our findings advocate for comprehensive policy frameworks that holistically address the complexities of coastal GDEs across the land‐sea continuum to foster their long‐term sustainability and conservation. [ABSTRACT FROM AUTHOR]

The devastating consequences of tsunamis on coastal infrastructure have highlighted the urgent need for effective disaster risk reduction strategies. To mitigate tsunami disasters, the insurance industry plays a vital role in implementing risk transfer measures by providing financial protection against asset damage. However, the current research on catastrophe insurance policies for coastal infrastructure lacks consideration of climate change effects. It is essential to take into account the non-stationary effects of sea-level rise to develop long-term tsunami disaster mitigation measures and promote socioeconomic resilience in coastal communities. This paper aims to provide an insurance portfolio optimization framework for coastal residential buildings subjected to tsunamis considering non-stationary sea-level rise effects based on a stochastic simulation approach. A spatiotemporal probabilistic sea-level rise hazard assessment is carried out by utilizing available climate models and considering several emission scenarios. Tsunami propagation analyses under various sea-level rise cases are performed to evaluate the time-variant tsunami hazard curves based on Monte Carlo simulation. A life cycle-based stochastic insurance claim model associated with the cumulative loss of building assets is developed based on a non-stationary compound renewal process. Finally, a sample average approximation method is leveraged to estimate the optimum basic insurance premium rate by maximizing the insurer's profit under a cost-constrained insurance purchase decision of homeowners. As a case study, the proposed framework is applied to multiple municipalities situated in the tsunami-prone region of Kochi Prefecture, Japan. Sea-level rise substantially decreases the maximum profits of tsunami insurers and increases the premium rate and ruin probability. [ABSTRACT FROM AUTHOR]

Coastal erosion and flooding are projected to increase during the 21st century due to sea-level rise (SLR). To prevent adverse impacts of unmanaged coastal development, national organizations can apply a land protection policy, which consists of acquiring coastal land to avoid further development. Yet, these reserved areas remain exposed to flooding and erosion enhanced by SLR. Here, we quantify the exposure of the coastal land heritage portfolio of the French Conservatoire du littoral (Cdl). We find that 30% (~40%) of the Cdl lands owned (projected to be owned) are located below the contemporary highest tide level. Nearly 10% additional surface exposure is projected by 2100 under the high greenhouse gas emissions scenario (SSP5-8.5) and 2150 for the moderate scenario (SSP2-4.5). The increase in exposure is largest along the West Mediterranean coast of France. We also find that Cdl land exposure increases more rapidly for SLR in the range of 0–1 m than for SLR in the range 2–4 m. Thus, near-future uncertainty on SLR has the largest impact on Cdl land exposure evolution and related land acquisition planning. Concerning erosion, we find that nearly 1% of Cdl land could be lost in 2100 if observed historical trends continue. Adding the SLR effect could lead to more than 3% land loss. Our study confirms previous findings that Cdl needs to consider land losses due to SLR in its land acquisition strategy and start acquiring land farther from the coast. [ABSTRACT FROM AUTHOR]

Shorelines face growing threats due to climate change and diminishing sand supply. Coastal headlands, common rocky features along coastlines, are crucial in shaping hydrodynamics and sediment transport. Yet, the influence of future climate conditions, including sea‐level rise (SLR) and intensified storm energy on complex shorelines with headlands has remained relatively unexplored. In this study, we model changes in hydrodynamics and headland bypassing under different SLR and higher storm wave scenarios. Our findings reveal the formation of circulation cells on both sides of a headland, where wave energy converges around the headland zone. Future climate conditions result in larger storm waves on the beach. However, SLR enhances nearshore currents through a landward shifting of the circulation cells, while higher storm waves intensify offshore flow currents due to the seaward movement of the cells. This effect, in turn, increases the potential for headland sediment bypassing. Plain Language Summary: Coastal headlands, prominent rocky features along open coastlines, play a crucial role in protecting nearby beaches from strong waves and erosion. They also affect how sand is exchanged between different beaches. We use a model to explore how future climate conditions including sea‐level rise (SLR) and larger storm waves influence coastal waves, littoral currents, and the transport of sand around headlands. Our findings reveal that headlands converge wave energy forming circulation flow cells. SLR results in stronger nearshore currents, driven by the landward movement of the rotating flow cells. In contrast, larger storm waves can move the rotating flow cells seaward, thereby increasing offshore current strength and the potential for sand transport around the headland. Understanding how coastal waves, flow and sediment transport change under future climate conditions will help determine coastal resilience. Key Points: The formation of circulation cells and wave energy convergence around headlands during storms reduce bottom shear stress at the beachSea‐level rise increases wave heights, currents, and bed shear stress in the nearshore because of landward shifting of the circulation cellsHigher storm waves expand the surf zone, shift circulation cells seaward, and enhance potential headland sediment bypassing [ABSTRACT FROM AUTHOR]

Coral reef islands are amongst the most vulnerable environments to sea‐level rise (SLR). Recent physical and numerical modeling studies have demonstrated that overwash processes may enable reef islands to keep up with SLR through island accretion. Sediment supply to these islands from the surrounding reef system is critical in understanding their morphodynamic adjustments, but is poorly constrained due to insufficient knowledge about sediment delivery rates. This paper provides the first estimation of sediment delivery rates to coral reef islands. Analysis of topographic and geochronological data from 28 coral reef islands indicates an average rate of sediment delivery of c. 0.1 m3 m−1 yr−1, but with substantial inter‐island variability. Comparison with carbonate sediment production rates from census‐based studies suggests that this represents one quarter of the amount of sediment produced on the reef platform. Results of this study are useful in future modeling studies for predicting morphodynamic adjustments of coral reef islands to SLR. Plain Language Summary: Low‐lying coral reef islands are under threat of sea‐level rise (SLR). However, when these islands are flooded, ocean waves can bring in sediment that can increase the island elevation. This would enable coral reef islands to better withstand flooding in the future. Knowing how much sediment is brought in will help in our understanding of future changes to these islands due to SLR. In this paper, we use data from 28 Indo‐Pacific coral reef islands to compute sediment supply to the islands. We find that on average 0.1 m3 of sediment (roughly 100 kg) is delivered each year for every meter of island shoreline. We further suggest that this implies that only one quarter of the sediments produced by the coral reef system is delivered to the island shoreline. Most of the sediment produced remains on the reef flat or is exported to the ocean or the lagoon. Our results will help future studies to predict more accurately how coral reef islands will adjust to SLR. Key Points: We provide the first estimates of carbonate sediment delivery rates to 28 coral reef islands using all data available from the literatureSediment delivery to the reef islands occurs at a rate of c. 0.1 m3 m−1 yr−1, but with substantial inter‐island variabilityWhere island building has been continuous through island history, long‐term delivery rates provide valuable estimates for contemporary rates [ABSTRACT FROM AUTHOR]

We use an observationally calibrated ice-sheet model to investigate the future trajectory of the Antarctic ice sheet related to uncertainties in the future balance between sub-shelf melting and ice discharge, on the one hand, and the surface mass balance, on the other. Our ensemble of simulations, forced by a panel of climate models from the sixth phase of the Coupled Model Intercomparison Project (CMIP6), suggests that the ocean will be the primary driver of short-term Antarctic mass loss, initiating ice loss in West Antarctica already during this century. The atmosphere initially plays a mitigating role through increased snowfall, leading to an Antarctic contribution to global mean sea-level rise by 2100 of 6 (- 8 to 15) cm under a low-emission scenario and 5.5 (- 10 to 16) cm under a very high-emission scenario. However, under the very high-emission pathway, the influence of the atmosphere shifts beyond the end of the century, becoming an amplifying driver of mass loss as the ice sheet's surface mass balance decreases. We show that this transition occurs when Antarctic near-surface warming exceeds a critical threshold of + 7.5 ∘ C, at which the increase in surface runoff outweighs the increase in snow accumulation, a signal that is amplified by the melt–elevation feedback. Therefore, under the very high-emission scenario, oceanic and atmospheric drivers are projected to result in a complete collapse of the West Antarctic ice sheet along with significant grounding-line retreat in the marine basins of the East Antarctic ice sheet, leading to a median global mean sea-level rise of 2.75 (6.95) m by 2300 (3000). Under a more sustainable socio-economic pathway, we find that the Antarctic ice sheet may still contribute to a median global mean sea-level rise of 0.62 (1.85) m by 2300 (3000). However, the rate of sea-level rise is significantly reduced as mass loss is likely to remain confined to the Amundsen Sea Embayment, where present-day climate conditions seem sufficient to commit to a continuous retreat of Thwaites Glacier. [ABSTRACT FROM AUTHOR]

Over the coming century, climate change and sea-level rise are predicted to cause widespread change to coastal wetlands. Estuarine vegetated wetlands can adapt to sea-level rise through both vertical development (i.e., biophysical feedbacks and sedimentation) and upslope/horizontal migration. Quantifying changes to estuarine vegetated wetlands over time can help to inform current and future decisions regarding land management and resource stewardship. In this study, we show how coastal land cover maps readily available in the US can be used to assess and understand estuarine vegetated wetland changes. This assessment involves two steps: (1) identifying the net gain/loss of estuarine vegetated wetlands and (2) determining which land cover types contribute to the net gain/loss. From this information, we developed estuarine vegetated wetland change scenarios that evaluate whether estuarine vegetated wetland gain kept up with loss and whether the contribution was from: (1) estuarine vegetated wetland migration or tidal restoration; (2) land building (i.e., development); or (3) both. We assessed changes from 1996 to 2016 for: (1) the conterminous US; (2) each major US coastline; and (3) focal estuaries with the most change per coast. We found that the change scenario (1, 2, or 3) varied across coastlines. Moving forward, national coastal land cover programs can be informed by utilizing methodologies that leverage contemporary information for delineating the estuarine zone from upslope/adjacent wetlands. We highlight approaches that could be used to address this challenge and provide complementary information related to wetland condition changes. [ABSTRACT FROM AUTHOR]

The study presents a multi-proxy archive from hypersaline coastal Lake Chokrak in eastern Crimea, a steppe region which is particularly susceptible to moisture fluctuations. XRF, organic carbon and nitrogen, and palynological analyses are used to reconstruct the evolution of the lake and landscape development around it and to provide information about the driving forces behind those changes, such as climate and human impact. The findings show that the basin was an open marine bay between 7640 and 5500 cal. yr BP. After 5500 cal. yr BP, the low rates of sea-level rise led to gradual infilling of the basin. The prevalence of mesic herb-grass steppe around the site, as well as the expansion of broad-leaved trees in the Crimean mountains, indicate relatively warm and humid climate conditions during the Mid-Holocene. Elemental proxies and marine NPPs point to a transition to lagoonal conditions from 4270 cal. yr BP. The progressive shallowing of the basin was accompanied by the spread of more xeric Artemisia -grass steppe, which suggests a shift to arid conditions. The occurrence of cereal pollen from 3660 cal. yr BP may indicate the first signs of cultivation in the study area. The active build-up of a sand barrier from 3000 cal. yr BP led to a gradual separation of the basin from the sea. By 900 cal. yr BP, the fully-formed sand barrier resulted in a transformation of the lagoon into a hypersaline lake. The closing of the lagoon was accompanied by an expansion of halophytic communities around the site. Human-induced vegetation changes became more pronounced with the development of agrarian and pastoral activities around the site from ca. 750 cal. yr BP. [ABSTRACT FROM AUTHOR]

Subglacial drainage networks regulate the response of ice sheet flow to surface meltwater input to the subglacial environment. Simulating subglacial hydrology evolution is critical to projecting ice sheet sensitivity to climate, and contribution to sea‐level change. However, current numerical subglacial hydrology models are computationally expensive, and, consequently, evolving subglacial hydrology is neglected in large‐scale ice sheet simulations. We present a deep learning emulator of a state‐of‐the‐art subglacial hydrology model, trained at multiple Greenland glaciers. Our emulator performs strongly in both temporal (R2 > 0.99) and spatial (R2 > 0.95) generalization, offers high computational savings, and can be used to force numerical ice sheet models. This will enable century‐ and large‐scale ice sheet model simulations, including interactions between ice flow and increased meltwater input to the subglacial environment. Generally, our work demonstrates that machine learning can further improve ice sheet models, reduce computational bottlenecks, and exploit information from high‐fidelity models and novel observational platforms. Plain Language Summary: Meltwater at the surface of ice sheets can drain to the subglacial environment, lubricate the bed, and influence ice sheet flow. Complex numerical subglacial hydrology models represent the subglacial drainage system, but are too computationally expensive to be included in large‐scale and long‐term ice sheet simulations. Consequently, model predictions of future ice sheet contribution to sea‐level rise ignore ice flow modulation by evolving subglacial hydrology. Here, we use deep learning to emulate a state‐of‐the‐art subglacial hydrology model. The emulator can directly force large‐scale ice sheet models to capture ice flow sensitivity to subglacial hydrology. The computational speed and accuracy of our emulator show the potential to use machine learning to efficiently incorporate previously neglected processes into ice sheet models. Key Points: We develop a deep learning emulator to simulate evolving subglacial hydrology in response to meltwater input for ice sheet simulationsThe emulator shows generalization capabilities, large computational savings, and can be used to force numerical ice sheet modelsWe demonstrate that machine learning has substantial potential in improving ice sheet models, through using information‐rich data sets [ABSTRACT FROM AUTHOR]

The Upper Cretaceous (Campanian) Belly River Group (BRG) of southern Alberta has a complex internal stratigraphic architecture derived from differential geometries of its component formations that resulted from regionalized tectonic influences and shifting source areas. A full understanding of BRG architecture has been compromised heretofore by a limited understanding of subsurface data in southwestern- and southeastern-most Alberta. In this study outcrop exposures throughout southern Alberta are tied to reference well logs and subsurface cross-sections allowing a more precise understanding of BRG architecture and how it relates to well-known vertebrate fossil producing areas. Modifications to an existing stratigraphic model of the BRG show that the Oldman and the Dinosaur Park formations have reciprocal north-to-south wedge-shaped geometries and a diachronous contact that become prominently expressed south of Twp 12. The updated model also demonstrates that the Oldman Formation thickens stratigraphically up-section to the south, and that the Foremost-Oldman contact is, essentially, a datum across much of southern Alberta. Identification of the Oldman Formation in the subsurface remains based on its relatively high gamma-ray response in mudstone successions, but it is also recognized that many of its sandstones exhibit relatively low gamma-ray responses like those in underlying and overlying formations. Nomenclature and subdivisions of the Oldman Formation are revised to accommodate this updated understanding, and modifications are also made to the definition of the Judith River-Belly River discontinuity, a newly recognized surface that marks the onset of accommodation and eustatic rise in sea-level in the northern Western Interior Basin at ~76.3 Ma. [ABSTRACT FROM AUTHOR]

Economic costs of climate change are conventionally assessed at the aggregated global and national levels, while adaptation is local. When present, regionalised assessments are confined to direct damages, hindered by both data and models' limitations. This article goes beyond the aggregated analysis to explore direct and indirect economic consequences of sea level rise (SLR) at regional and sectoral levels in Europe. Using a dynamic computable general equilibrium model and novel datasets, we estimate the distribution of losses and gains across regions and sectors. A comparison of a high-end scenario against a no-climate-impact baseline suggests a GDP loss of 1.26% (€871.8 billion) for the whole EU&UK. Conversely our refined assessments show that some coastal regions lose 9.56–20.84% of GDP, revealing striking regional disparities. Inland regions grow due to the displaced demand from coastal areas, but the GDP gains are small (0–1.13%). While recovery benefits the construction sector, public services and industry face significant downturns. We show that prioritising recovery of critical sectors locally reduces massive regional GDP losses, at negligible costs to the overall European economy. Our analysis traces regional economic restructuring triggered by SLR, underscoring the necessity of region-specific adaptation policies that embrace uneven geographic impacts and unique sectoral profiles to inform resilient strategy design. [ABSTRACT FROM AUTHOR]

Ocean heat content (OHC) is a depth-integrated physical oceanographic variable used to precisely measure ocean warming. Because of the limitations associated with in-situ CTD data and Ocean Reanalysis system products, satellite-based approaches have gained importance in estimating the daily to decadal variability of OHC over the vast oceanic region. Efforts to minimize the biases in satellite-based OHC estimates are needed to realize the actual response of the ocean to the brunt of climate change. In the current study, an attempt has been made to better implement the satellite-based ocean thermal expansion method to estimate OHC at 17 depth extents ranging from the surface to 700m. To achieve this objective, an artificial neural network (ANN) model was developed to derive thermosteric sea level (TSL) from a given dataset of sea surface temperature, sea surface salinity, geographical coordinates, and climatological TSL. The model-derived TSL data were used to estimate OHC changes based on the thermal expansion efficiency of heat. Statistical analysis showed high correlation coefficients and low errors in satellite-derived TSL / OHC at 700 m water depth (N 388469, R 0.9926 / 0.9922, RMSE 1.16 m / 1.56 GJ m-2, MBE -0.1917 m / -0.2400 GJ m-2, MBPE -0.4560% / -0.0290%, MAE 0.763 m / 1.029 GJ m-2, and MAPE 2.34% / 0.13%) and nearly similar results at the remaining depth extents. These results suggest that the proposed ANN models are capable of accurately estimating OHC changes on real-time data and three-dimensional distribution patterns of depth-integrated OHC trends in the global ocean. In addition, the first-ever attempt to estimate the ocean thermal expansion component (i.e., TSL) from satellite data was successful and the model-derived TSL can be used to obtain high-end sea-level rise products in the global ocean. [ABSTRACT FROM AUTHOR]

Coastlines globally are sensitive to the effects of sea-level rise, increased coastal storminess and changes in coastal sediment supply and sediment dynamics in the Anthropocene. Coastlines are also influenced by land use change, urbanization and development of built infrastructure. These changes can affect the dynamics of coastal landforms, weaken coastal resilience and make coasts more sensitive to climate hazards. This study critically examines the properties of coastlines that contribute to coastal biophysical resilience in South Africa, highlighting their relativerates of change and dynamic behaviour in response to physical and human forcing factors. Coastal landforms can be considered as 'green infrastructure' that can buffer the effects of climate change as well as providing ecosystem and environmental services in their own right. Viewing coastal landforms as green infrastructure provides a 'nature-based solution' to mitigate against climate change impacts that can work with – not against – the natural geomorphic, sedimentary and ecological processes of coastlines. Coastal landforms can also contribute to socioecological resilience, where they provide environmental and ecosystem services. The green infrastructure approach to coastal resilience has not been well developed in South Africa but is more effective in supporting coastal sustainable development. [ABSTRACT FROM AUTHOR]

The increased melting and rapid retreat of marine-terminating glaciers is a key contributor to sea-level rise. In glacial fjords with shallow sills common in Patagonia, Alaska, and other systems, these bathymetric features can act as a first-order control on the dynamics. However, our understanding of how this shallow bathymetry interacts with the subglacial discharge from the glacier and impacts the fjord circulation, water properties, and rates of submarine melting is limited. To address this gap, we conduct idealized numerical simulations using a coupled plume–ocean fjord model spanning a wide range of initial ocean conditions, sill depths, and subglacial discharge. A previously documented circulation regime leads to strong mixing and vertical transport over the sill, where up to ∼ 70 % of the colder water from the upper-layer outflow is refluxed into the deeper layer, cooling the incoming warm oceanic water by as much as 1 ∘C and reducing the stratification near the glacier front. When the initial stratification is relatively strong or the subglacial discharge is relatively weak, an additional unsteady circulation regime arises where the freshwater flow can become trapped below the sill depth for weeks to months, creating an effective cooling mechanism for the deep water. We also find that submarine melting often increases when a shallow sill is added to a glacial fjord due to the reduction of stratification – which increases submarine melting – dominating over the cooling effect as the oceanic inflow is modified by the presence of the sill. These results underscore that shallow-silled fjords can have distinct dynamics that strongly modulate oceanic properties and the melting rates of marine-terminating glaciers. [ABSTRACT FROM AUTHOR]

Thin, condensed coarse-grained shallow marine successions can be difficult to describe and interpret, especially in the subsurface since the recognition of finer-grained intervals, typically associated with sequence stratigraphic surfaces, is challenging. This lack of mudstones and siltstones means that they also typically make excellent reservoir intervals. The Oxfordian to Volgian intra-Draupne Formation sandstones in the Johan Sverdrup Field, southern Utsira High, represent such a system. This study presents a new sequence stratigraphic model for the Johan Sverdrup Field that unravels the detailed depositional history of the succession and places its formation within a regional Late Jurassic tectonostratigraphic framework. The intra-Draupne Formation sandstones comprise four parasequences deposited following a regional Kimmeridgian marine flooding event. Sediments were mainly supplied through West-derived fan deltas from the Haugaland High and NW-SE-directed tidal currents reworking the Augvald Graben and the Avaldsnes High at the East. The oldest parasequence shows a distinctive suite of facies consisting of fine-grained and mud-rich bioturbated sandstones deposited in a semi-restricted lagoon. Subsequent parasequences lack fine-grained sediments and are dominated by bidirectional cross-stratified, very coarse-to coarse-grained sandstones and gravels deposited in a tidal strait. A progressive reduction of fault-related subsidence in the Middle Volgian along with Late Volgian-Ryazanian sea-level rise and inversion of pre-existing structures promoted backstepping of the feeder systems, sediment starvation and the progressive deposition of the black and green-red shales of the Draupne and Asgard formations. The results of this study account for features previously unidentified in the Johan Sverdrup Field and which have implications for understanding the deposition of coarse-grained shallow marine successions around the Utsira High and other transgressed basement highs. [ABSTRACT FROM AUTHOR]

Coastal landscapes are naturally shifting mosaics of distinct ecosystems that are rapidly migrating with sea-level rise. Previous work illustrates that transitions among individual ecosystems have disproportionate impacts on the global carbon cycle, but this cannot address nonlinear interactions between multiple ecosystems that potentially cascade across the coastal landscape. Here, we synthesize carbon stocks, accumulation rates, and regional land cover data over 36 years (1984 and 2020) for a variety of ecosystems across a large portion of the rapidly transgressing mid-Atlantic coast. The coastal landscape of the Virginia Eastern Shore consists of temperate forest, salt marsh, seagrass beds, barrier islands, and coastal lagoons. We found that rapid losses and gains within individual ecosystems largely offset each other, which resulted in relatively stable areas for the different ecosystems, and a 4% (196.9 Gg C) reduction in regional carbon storage. However, new metrics of carbon replacement times indicated that it would take only ~ 7 years of carbon accumulation in surviving ecosystems to compensate this loss. Our findings reveal unique compensatory mechanisms at the scale of entire landscapes that quickly absorb losses and facilitate increased regional carbon storage in the face of historical and contemporary sea-level rise. However, the strength of these compensatory mechanisms may diminish as climate change exacerbates the magnitude of carbon losses. [ABSTRACT FROM AUTHOR]

Ghost forests consisting of dead trees adjacent to marshes are striking indicators of climate change, and marsh migration into retreating coastal forests is a primary mechanism for marsh survival in the face of global sea‐level rise. Models of coastal transgression typically assume inundation of a static topography and instantaneous conversion of forest to marsh with rising seas. In contrast, here we use four decades of satellite observations to show that many low‐elevation forests along the US mid‐Atlantic coast have survived despite undergoing relative sea‐level rise rates (RSLRR) that are among the fastest on Earth. Lateral forest retreat rates were strongly mediated by topography and seawater salinity, but not directly explained by spatial variability in RSLRR, climate, or disturbance. The elevation of coastal tree lines shifted upslope at rates correlated with, but far less than, contemporary RSLRR. Together, these findings suggest a multi‐decadal lag between RSLRR and land conversion that implies coastal ecosystem resistance. Predictions based on instantaneous conversion of uplands to wetlands may therefore overestimate future land conversion in ways that challenge the timing of greenhouse gas fluxes and marsh creation, but also imply that the full effects of historical sea‐level rise have yet to be realized. [ABSTRACT FROM AUTHOR]

Denmark has been subject to complex interactions of isostatic uplift and eustatic sea level changes since the last deglaciation. Prominent coastal beach ridges as well as lagoonal and lake deposits from this period have been investigated at a number of sites in the region to constrain the relative sea level (RSL) changes. However, despite the common occurrence of former coastal lagoons and lakes in proximity to raised beach ridges, they have rarely been studied in combination. In this study, we use a multiproxy approach including geospatial data, lake sediment coring, ground penetrating radar and optically stimulated luminescence dating to investigate the Holocene coastal evolution and RSL history at Rugård in Mols Bjerge National Park, on the east coast of the Jutland Peninsula. Our results show that the coastal area at Rugård was transgressed between c. 7.6 and 7.0 cal. ka BP and that RSL was ~4.5 m higher than present between c. 6.6 and 5.9 ka ago, when the highest section of the beach ridge plain was deposited. The elevation and timing of this relative highstand are in good agreement with previous estimates of the Littorina transgression and contribute to our combined knowledge about RSL history and coastal evolution in the southern Kattegat. Subsequently, isostatic adjustment has caused uplift and erosion of the beach ridge plain, but renewed progradation and deposition of a lower beach plain have taken place since c. 1740 CE. Our results demonstrate the value of using a multiproxy approach to study RSL changes and coastal evolution. [ABSTRACT FROM AUTHOR]

As the main contributor to global sea-level rise, the Greenland Ice Sheet (GrIS) has undergone significant mass change over the last two decades. The satellite mission of GRACE (Gravity Recovery And Climate Experiment) and its follow-on mission (GRACE-FO) provide accurate observations but low-spatial resolution. In contrast, satellite altimetry provides observations at a high-spatial resolution but with large uncertainties, limiting the understanding of glacier-scale mass change. To derive accurate and high-spatial resolution mass change estimates from GRACE/GRACE-FO observations, we present a novel constraint mascon method in which the regularization matrix is constructed with the signal variances from satellite altimetry. Based on the proposed method, we derive a series of high-resolution (25 km × 25 km) monthly mascon solutions from 2002 April to September. The glacier-scale estimates from the input–output method agree better with those from our mascon solutions than those from the global mascons of CSR (Center for Space Research, the University of Texas), JPL (Jet Propulsion Laboratory), and GSFC (Goddard Space Flight Center), with a higher linear regression coefficient of 0.71. Benefitting from the greatly improved spatial resolution, our estimates provide the first accurate monthly glacier-scale mass change estimates from GRACE/GRACE-FO observations over the GrIS, to our knowledge. The results show that 20 of the 260 glaciers contributed to more than 42 per cent of the ice loss in the GrIS from 2002 to 2022. Most strikingly, the mass loss of Jakobshavn Isbrae was the most significant at –18.7 ± 0.05 Gt yr−1, accounting for 7.4 per cent of the total in the GrIS during the study period. Furthermore, we find that the SMB (surface mass balance) and ice-dynamics-related mass changes contribute nearly equally to the observed mass changes, but the corresponding spatiotemporal characteristics differ. SMB contributed the most to the mass change in 2019, while ice dynamics played the most dominant role in 2018. Moreover, the SMB effect is widespread, and ice-dynamics-related mass loss is mainly concentrated in five small areas. [ABSTRACT FROM AUTHOR]

Bleaching events impact coral reef functionality and carbonate budget dynamics, which is reflected in reduced reef framework accretion, hindering reef ability to keep pace with sea-level rise projections. Reefs in the Arabian Gulf exist in harsh environmental conditions with seasonal temperatures ranging between 16 and 36 °C. Despite the high thermal thresholds (~ 35 °C) of corals in this region, extensive bleaching and high coral mortality have been reported regionally in 2017. We quantify reef carbonate budgets at a near shore and an offshore reef site in Bahrain pre-bleaching in May 2017 and post-bleaching in May 2018 to assess the impacts of the 2017 severe bleaching event on the budgetary state. Results indicate an overall decrease in hard coral cover from 14.2 ± 5.5 to 8.5 ± 1.4% and a decline in the net carbonate budget state from 3.6 ± 2.2 to 0.3 ± 0.3 kg CaCO3 m−2 year−1 at the shallow nearshore Fasht Al Adhm reef indicating a shift from a positive budgetary state to net neutral, while the deeper offshore Reef Bul Thamah has increased positively from 3.7 ± 1.2 to 4.2 ± 0.6 kg CaCO3 m−2 year−1. We attribute the decline in the nearshore reef to the bleaching event which took place between July and October 2017, resulting in high coral mortality rates and subsequent reduced framework carbonate production. Predicted warming trends present a threat to the structural integrity of shallow Bahraini reefs, compromising their ability to keep pace with future sea-level rise projections. [ABSTRACT FROM AUTHOR]

Assessing at-sea distributions and behaviour of seabirds to identify critical foraging sites and spatial overlap with potential threats is a major step for delineating conservation guidelines. The West African Crested Tern (Thalasseus albididorsalis) is the most abundant breeding tern in West Africa, nesting from Mauritania to Guinea. Its restricted breeding range and exclusive nesting at coastal low-lying areas, place this species at particular risk of losing suitable breeding and resting sites as a consequence of current global changes, namely, sea-level rise. The at-sea distribution of this species is mostly unknown, and therefore, the specific threats faced are still unidentified. Here, we characterize the foraging behaviour and distribution of West African Crested terns breeding at the world's second-largest colony of the species, in Guinea-Bissau, by tracking 20 individuals. Overall, terns took an average of 2 trips per day, travelling on average 100 km per trip, but often reaching areas up to 120 km from the colony. Shallow waters, usually not exceeding 10 m in depth, and upwelling areas were mostly used as foraging sites. Nocturnal movements, rarely reported on terns, suggest active foraging at night. Key foraging and resting sites were identified, which altogether may regularly hold 2.5–23% of the global breeding population of the West African Crested Tern. These areas are only partly (ca. 50%) covered by the existing marine Important Bird and Biodiversity Area (IBA). Therefore, our results should be considered in any re-evaluation of the IBA borders. [ABSTRACT FROM AUTHOR]

Coastal water supply infrastructure systems (CWSISs) are exposed to saltwater intrusion (SWI) exacerbated by sea level rise (SLR) stressors. However, most existing definitions of CWSIS resilience are confined to the system's global severity, while uncertainties from SLR are not considered. In this paper, we develop a CWSIS model considering uncertainties from SLR and define a new formula for resilience based on three components of system severity, i.e., social severity (SevS) affected by water shortages to end users, regional severity (SevR) caused by water shortages in water treatment plants (WTPs), and technological severity (SevT) considering water shortages in wells. A case study in Xingcheng is designed to (1) examine the resilience response of CWSISs to future SLR, (2) identify vulnerable components, and (3) compare the cost-effectiveness of different measures for enhancing resilience using scenario analysis with full consideration of future uncertainties from SLR. This paper contributes to the development of sustainability assessments for urban water systems subject to future sea level change. Finding response measures with high adaptiveness across a variety of future scenarios is crucial for establishing a sustainable urban water system in the long term. [ABSTRACT FROM AUTHOR]

This review article delves into the latest advancements and transformative impacts of remotely sensed methods in measuring water depth and underwater topography. It particularly focuses on topobathymetric data acquisition which is crucial for numerous applications including navigation, flood control, coastal erosion, sea-level rise predictions, and mapping, modelling, and monitoring of offshore resources. Traditionally, measuring depths, distribution, and volumes of submerged resources has been challenging due to time, cost, labor, and reliance on sophisticated, mostly airborne technologies. These conventional methods often struggled in remote, hazardous, or shallow water areas. Recent advances in Light Detection and Ranging (LiDAR) technology, especially its miniaturization and integration with unoccupied aerial systems (UAS), have significantly improved the collection of three-dimensional bathymetric data. This progress presents effective solutions for previously faced challenges. Despite these advancements, there's a need for a thorough assessment of the state of LiDAR-based topobathymetric mapping and the impact of the increasing accessibility of UAS in this field. Our systematic review scrutinizes topobathymetric LiDAR technology and research, centering on acquisition platforms and methods in coastal and riverine environments for mapping, planning, monitoring, and inspections. We document the spread of topobathymetric LiDAR research over time, geographically, across disciplines, and in various publication outlets. Utilizing the VOSviewer analytical tool, we conducted a bibliometric keywordbased network analysis, evaluating the distribution of topobathymetric citations, and their bibliographic coupling, co-citation, and co-authorship relationships. Our findings reveal the innovative yet emerging state of UAS applications in topobathymetry and the ongoing reliance on LiDAR technology for 3-D underwater data acquisition. This study provides a fundamental assessment of current trends and developments in coastal and riverine bathymetric applications, highlighting the evolving landscape of remotely sensed methods in underwater topography. [ABSTRACT FROM AUTHOR]

Future sea-level rise projections are characterized by both quantifiable uncertainty and unquantifiable structural uncertainty. Thorough scientific assessment of sea-level rise projections requires analysis of both dimensions of uncertainty. Probabilistic sea-level rise projections evaluate the quantifiable dimension of uncertainty; comparison of alternative probabilistic methods provides an indication of structural uncertainty. Here we describe the Framework for Assessing Changes To Sea-level (FACTS), a modular platform for characterizing different probability distributions for the drivers of sea-level change and their consequences for global mean, regional, and extreme sea-level change. We demonstrate its application by generating seven alternative probability distributions under multiple emissions scenarios for both future global mean sea-level change and future relative and extreme sea-level change at New York City. These distributions, closely aligned with those presented in the Intergovernmental Panel on Climate Change Sixth Assessment Report, emphasize the role of the Antarctic and Greenland ice sheets as drivers of structural uncertainty in sea-level change projections. [ABSTRACT FROM AUTHOR]

Sets of beach ridge plains and sand spit at Laem Pho, Chaiya coast of Surat Thani, the Thai-Malay peninsula, the Gulf of Thailand show their evolution in response to a long-term sea-level change from the middle Holocene to the present. The most landward set of beach ridges defines the paleo-shoreline located at 4.5 km far inland with an elevation up to 4 m of ancient sea level above the present mean sea level. Interestingly, the orientation of beach ridges reflects that they were mainly formed by longshore current in southeast direction likely similar to beach ridges in the other coastal sectors of the western part of the Gulf. The major composition of beach ridge included quartz, whereas minor composition was feldspar. Roundness and sphericity of beach ridge sediments showed sub-rounded and sub-angular. Physical properties of beach sediment and the preservation of feldspar in beach sediment suggest the main source from granite exposure near this coastal plain. Major sediment pathway was possibly supplied from the Phum Rieng canal. Optically stimulated luminescence dating revealed the formation of beach ridge plain here starting from 7,171±460 years BP. The sand spit has been formed at 440 years BP. These ages responded to the formation of beach ridge after sea level had reached the highstand in the middle Holocene. [ABSTRACT FROM AUTHOR]

This review examines the transition of coastal micro-outlets to micro-estuaries, to fully functional and species rich estuaries of various types. The definitions of the different types of microsystems are reviewed and it is apparent that an estuary is not simply a coastal water body where river and seawater meet. A range of other conditions, especially regular marine-estuarine connectivity and the persistence of a relatively large waterbody, are required for a flourishing estuarine biota to become established. In contrast to many global countries, the South African coastline has a continuum of coastal microsystems that cover the full spectrum of micro-outlets of various sizes, through micro-estuaries in the process of becoming estuarine systems, to a range of fully functional estuaries such as temporarily open/closed and predominantly open estuaries, to large estuarine lakes and bays. The impact of sea-level rise and fall on the exposure or inundation of coastal waterfalls is also examined, thus providing additional insights into the transformation of a freshwater outlet into a functional estuary. Furthermore, the creation of artificial concrete canal outlets in some of the major coastal cities is documented, with some estuaries being lost in the process. [ABSTRACT FROM AUTHOR]

Melt rates at the base of Antarctic ice shelves are needed to drive projections of the Antarctic ice sheet mass loss. Current basal melt parameterizations struggle to link open ocean properties to ice‐shelf basal melt rates for the range of current sub‐shelf cavity geometries around Antarctica. We present a proof of concept exploring the potential of simple deep learning techniques to parameterize basal melt. We train a simple feedforward neural network, or multilayer perceptron, acting on each grid cell separately, to emulate the behavior of circum‐Antarctic cavity‐resolving ocean simulations. We find that this kind of emulator produces reasonable basal melt rates for our training ensemble, at least as close as or closer to the reference than traditional parameterizations. On an independent ensemble of simulations that was produced with the same ocean model but with different model parameters, cavity geometries and forcing, the neural network yields similar results to traditional parameterizations on present conditions. In much warmer conditions, both traditional parameterizations and neural network struggle, but the neural network tends to produce basal melt rates closer to the reference than a majority of traditional parameterizations. While this shows that such a neural network is at least as suitable for century‐scale Antarctic ice‐sheet projections as traditional parameterizations, it also highlights that tuning any parameterization on present‐like conditions can introduce biases and should be used with care. Nevertheless, this proof of concept is promising and provides a basis for further development of a deep learning basal melt parameterization. Plain Language Summary: A warmer ocean around Antarctica leads to higher melting of the floating ice shelves, which influence the ice loss from the Antarctic ice sheet and therefore sea‐level rise. In computer simulations of the ocean, these ice shelves are often not represented. For simulations of the ice sheet, so‐called parameterizations are used to link the oceanic properties in front of the shelf and the melt at their base. We show that this link can be emulated with a simple neural network, which performs at least as well as traditional physical parameterizations both for present and much warmer conditions. This study also proposes several potential ways of further improving the use of deep learning to parameterize basal melt. Key Points: We show that simple neural networks produce reasonable basal melt rates by emulating circum‐Antarctic cavity‐resolving ocean simulationsPredicted melt rates for present and warmer conditions are similar or closer to the reference simulation than traditional parameterizationsWe show that neural networks are suited to be used as basal melt parameterizations for century‐scale ice‐sheet projections [ABSTRACT FROM AUTHOR]

This study evaluates the susceptibility of the coastal regions on the Thrace Peninsula to sea-level rise (SLR) and the corresponding vulnerability to climate change. To achieve this, a high-resolution digital elevation model with a 5 m granularity was used to apply the Coastal Vulnerability Index, adjusted for region-specific coastal sensitivity factors. Various global mean sea-level rise scenarios were examined for the near-term (2020–2050), mid-term (2050–2100), and long-term (2100–2300) to assess the impact of SLR. The examination of the immediate consequences of SLR on coastal areas included the analysis of land cover characteristics in the near-term. Results indicate that the Thrace Peninsula is highly susceptible to natural and socio-economic hazards caused by SLR. The concentration of population and socio-economic activities in coastal regions is a primary contributing factor to this vulnerability. In addition, hydrodynamic models are used to enhance understanding of the effects of SLR. The study reveals limited preparedness for planned adaptations to SLR in the region. The data highlight the crucial necessity for policymakers, researchers, and stakeholders to collaborate in executing strategic interventions and proactive initiatives. Upholding the ecological, economic, and societal welfare of the Thrace Peninsula, as well as comparable areas, necessitates addressing both the vulnerability and resilience of immediate coastal regions. [ABSTRACT FROM AUTHOR]

The Cross-Hosgri slope is a bathymetric lineament that crosses the main strand of the Hosgri fault offshore Point Estero, central California. Recently collected chirp seismic reflection profiles and sediment cores provide the basis for a reassessment of Cross-Hosgri slope origin and the lateral slip rate of the Hosgri fault based on offset of the lower slope break of the Cross-Hosgri slope. The Cross-Hosgri slope is comprised of two distinct stratigraphic units. The lower unit (unit 1) overlies the post-Last Glacial Maximum transgressive erosion surface and is interpreted as a Younger Dryas (ca. 12.85-11.65 ka) shoreface deposit based on radiocarbon and optically stimulated luminescence (OSL) ages, Bayesian age modeling, seismic facies, sediment texture, sediment infauna, and heavy mineral component. The shoreface was abandoned and partly eroded during rapid sea-level rise from ca. 11.5 to 7 ka. Unit 2 consists of fine sand and silt deposited in a midshelf environment when the rate of sea-level rise slowed between ca. 7 ka and the present. Although unit 2 provides a thin, relatively uniform cover over the lower slope break of the older shoreface, this feature still represents a valuable piercing point, providing a Hosgri fault slip rate of 2.6 ± 0.8 mm/yr. Full-waveform processing of chirp data resulted in significantly higher resolution in coarser-grained strata, which are typically difficult to interpret with more traditional envelope processing. Our novel combination of offshore radiocarbon and OSL dating is the first application to offshore paleoseismic studies, and our results indicate the utility of this approach for future marine neotectonic investigations. [ABSTRACT FROM AUTHOR]

This study considers climate impacts and environmental challenges (flooding and sea-level rise) in one of the coastal informal settlements in Lagos, Nigeria. A mix of methods was used to generate data. First, 14 residents, selected through purposive sampling, were interviewed. A survey (sample size = 300) of residents was conducted as a follow-up to the interviews. To elicit information on spatio-temporal dimensions, GIS-based mapping showed change in land use/cover from 1990 to 2020 and simulates impacts with 0.5 m, 1 m, 1.5 m and 2 m sea level rise scenarios. The results illuminate negative corollaries at the intersection of informal urbanisation and climate change in coastal settings. Flood-related impacts on the built and natural environment were significant. Climate adaption and resilience will need to involve restoring the decimated natural ecosystem and integration of indigenous systems in the study area and similar low-income coastal urban communities. [ABSTRACT FROM AUTHOR]

Intertidal ecology has been considered the cradle of modern marine ecology with insightful investigations on the biological and ecological mechanisms allowing "life between the tides". Most of the early investigations focused on macrophytes (seagrasses and macroalgae) and benthic invertebrates inhabiting emerged intertidal substrata. However, tidepools also shelter a rich fauna, including fishes, which display a wide diversity and a variety of ecological interactions and functions. Here, we review the diversity, ecology, evolution and conservation of the American tidepool fishes, from definition to trophic roles, ecological vulnerabilities and societal importance that reveal an extraordinary biodiversity and the important roles fishes play in the coastal ecosystems. Tidepool fish studies increased sharply from the mid twentieth century onwards, but many geographic gaps still exist. Tidepool fishes connect marine and terrestrial communities via substantial predation upon insects and exporting energy to land as prey for terrestrial fauna. Sea-level rise driven by climate change will reduce or eliminate current intertidal habitats, where little or no space is available for landward accommodation in the supralittoral zone. Concurrently, tidepool habitat would be 'squeezed' to a narrow intertidal stripe by 'coastal squeeze' process. Endemic, habitat-restricted, and specialist species could be particularly affected by human-induced habitat loss on the coastal stripe. Tidepool fishes provide many ecological services, such as well-being, environmental awareness, outdoor recreation, and bioinspiration for ancient and current societies. The level of intertidal rocky shore protection varies among American countries, but in most cases rocky shores are included in the least effective protection categories allowing extractive activities. [ABSTRACT FROM AUTHOR]

Summary: Predicting the fate of coastal marshes requires understanding how plants respond to rapid environmental change. Environmental change can elicit shifts in trait variation attributable to phenotypic plasticity and act as selective agents to shift trait means, resulting in rapid evolution. Comparably, less is known about the potential for responses to reflect the evolution of trait plasticity.Here, we assessed the relative magnitude of eco‐evolutionary responses to interacting global change factors using a multifactorial experiment. We exposed replicates of 32 Schoenoplectus americanus genotypes 'resurrected' from century‐long, soil‐stored seed banks to ambient or elevated CO2, varying levels of inundation, and the presence of a competing marsh grass, across two sites with different salinities.Comparisons of responses to global change factors among age cohorts and across provenances indicated that plasticity has evolved in five of the seven traits measured. Accounting for evolutionary factors (i.e. evolution and sources of heritable variation) in statistical models explained an additional 9–31% of trait variation.Our findings indicate that evolutionary factors mediate ecological responses to environmental change. The magnitude of evolutionary change in plant traits over the last century suggests that evolution could play a role in pacing future ecosystem response to environmental change. See also the Commentary on this article by Kottler, 240: 1714–1716. [ABSTRACT FROM AUTHOR]

Although shell middens and mounds often occupy the same intertidal spaces as coastal wetlands, biophysical interactions between these cultural features and wetlands are under-investigated. To this end, our geoarchaeological and zooarchaeological research at three coastal archaeological sites within the Tampa Bay Estuary, USA, sought to understand the interactions between shell-bearing sites, sea-level rise, storms, and migrating wetland habitats. Percussion core transects document the accretion of mangrove peat atop intact shell midden, illustrating the ability of mangrove forests to encroach shell midden and preserve cultural material below. Landward wetland deposits are thicker and muddier than those along the seaward margin of the sites, suggesting that shell-bearing sites attenuate wave energy much like other shoreline stabilization structures. Differences in sedimentology, stratigraphy, and invertebrate species compositions highlight the variability in storm impacts between sites. Storm-driven depositional events are identified by medium-to-fine sand beds with high densities of fragmented shell and small intertidal zone snails. Geospatial analyses indicate that wetland encroachment is already occurring at 247 archaeological sites within the Tampa Bay Estuary. Approximately 100 additional archaeological sites currently located in upland habitats may provide topographic relief for migrating coastal wetlands in the future. We contend that shell middens and mounds constructed by Indigenous peoples are important components within estuarine mosaics, as they have been for millennia. We advocate for further collaboration between archaeologists and estuary managers and the inclusion of descendant communities to co-manage the future of their past. [ABSTRACT FROM AUTHOR]

Climate change and sea-level rise cause seawater intrusion into freshwater ecosystems, risking increased salinity exposure for freshwater fish, endangering their long-term sustenance. To understand the effects of environmentally realistic increase in salinity exposure on freshwater fish, a total of 120 banded gourami, Trichogaster fasciata ( 8.54 g average initial weight) were exposed to four different salinities (0, 3, 6, and 9‰) for 90 days. The weight gain and specific growth rate values were significantly higher in the fish exposed to 3‰ compared to 0‰, and the lowest feed conversion ratio and survival rate were recorded in 3‰ and 9‰, respectively. The blood glucose and hemoglobin contents were found to be significantly higher and lower at 9‰ after 30 and 60 days, respectively, relative to 0‰. Moreover, significant low red blood cell counts were found at 6 and 9‰ after 30 and 90 days, respectively. Whereas, the white blood cell counts showed an opposite trend. Abnormalities of erythrocyte shape were significantly higher at 9‰, compared to 0‰. Results suggest that long-term exposure to high salinity (6, and 9‰) would cause osmotic stress and impair the physiological performance of freshwater gourami. [ABSTRACT FROM AUTHOR]

Low-lying, tropical coral reef-lined coastlines are becoming increasingly vulnerable to wave-driven flooding due to population growth, coral reef degradation, and sea-level rise. Early-warning systems (EWS) are needed to enable coastal authorities to issue timely alerts and coordinate preparedness and evacuation measures for their coastal communities. At longer time scales, risk management and adaptation planning require of robust assessments of future flooding hazard considering uncertainties. However, due to diversity in reef morphologies and complex reef hydrodynamics compared to sandy shorelines, there have been no robust, analytical solutions for wave runup to allow the development of large-scale coastal wave-driven flooding EWS and risk assessment frameworks for reef-lined coasts. To address the need for a fast, robust prediction of runup along reef-lined coasts, we constructed the BEWARE-2 (Broad-range Estimator of Wave Attack in Reef Environments) meta-process modeling system. We developed this meta-process model using a training dataset of hydrodynamics and wave runup computed by the XBeach Non-Hydrostatic+ process-based hydrodynamic model for 440 combinations of water level, wave height, and wave period on 195 morphologically diverse representative reef profiles. In validation, the BEWARE-2 modeling system produced runup results that had a root-mean square error of 0.63 m and bias of 0.26 m, relative to runup of 0.17–20.9 m simulated by XBeach Non-Hydrostatic+ for a large range of oceanographic forcing conditions and for a diverse reef morphologies. Incorporating parametric modifications in the modeling system to account for variations in reef roughness and beach slope allows systematic errors (relative bias) in BEWARE-2 predictions to be reduced by a factor of 1.5–6.5 for relatively coarse or smooth reefs, and mild or steep beach slopes. This relatively accurate solution is provided by the BEWARE-2 modeling system 4–5 orders of magnitude faster than the full, process-based hydrodynamic model and could therefore be integrated in large-scale EWS for tropical, reef-lined coasts, as well as used for large-scale flood risk assessments. [ABSTRACT FROM AUTHOR]

River sediments play a critical role in sustaining deltaic wetlands. Therefore, concerns are raised about wetlands' fate due to the decline of river sediment supply to many deltas. However, the dynamics and drivers of suspended sediment near deltaic coasts are not comprehensively assessed, and its response to river sediment supply changes remains unclear. Here we examine patterns of coastal suspended sediment concentration (SSC) and river sediment plume area (RPA) for 349 deltas worldwide using satellite images from 2000 to 2020. We find a global increase in SSC and RPA, averaging +0.46% and +0.48% yr−1, respectively, with over 59.0% of deltas exhibiting an increase in both SSC and RPA. SSC and RPA increases are prevalent across all continents, except for Asia. The relationship between river sediment supply and coastal SSCs varies between deltas, with as much as 45.2% of the deltas showing opposing trends between river sediments and coastal SSCs. This is likely because of the impacts of tides, waves, salinity, and delta morphology. Our observed increase in SSCs near river delta paints a rare promising picture for wetland resilience against sea-level rise, yet whether this increase will persist remains uncertain. River sediments play a critical role in sustaining coastal ecosystems. This study examines patterns of coastal suspended sediment concentration (SSC) for 349 deltas worldwide via satellite images and investigated the possible driving factors. [ABSTRACT FROM AUTHOR]

Florida Bay, a large and shallow estuary, serves as a vital habitat for a diverse range of marine species and holds significant environmental, commercial, and recreational value. The salinity structure of the bay plays a key role in the bay's ecosystem. Florida Bay receives 45% of its freshwater directly from rainfall, the largest source of freshwater, while the Taylor River is the second largest source. A hydrodynamic model was applied to determine if doubling the Taylor River flow, as currently planned, is adequate to meet salinity performance measures and protect the bay's ecosystem health. Model-predicted salinity indicated that rainfall caused the largest reduction (10–15 ppt) followed by Taylor River discharges, and none of the predicted salinity scenario means exceeded 38 ppt. The salinity restoration target was achieved more than 70% of the time, by doubling the Taylor River freshwater discharges, only for the existing bay conditions. To protect Florida Bay's ecosystem health and counterbalance saltwater intrusion in the Everglades wetlands, caused by future sea-level rise, additional freshwater sources needs to be identified. Yet, the question becomes, do we have enough available freshwater sources to achieve the restoration target and protect the bay's ecosystem health now and for future sea-level rise? [ABSTRACT FROM AUTHOR]