Sea-level Changes Research Articles

Late Jurassic paleoenvironmental reconstruction based on stable oxygen isotopes in bulk carbonates from the Qiangtang Basin, eastern Tethys

A composite eastern Tethyan oxygen and carbon isotope curve reveals major climate changes through the Late Jurassic. Despite significantly lower values and different amplitudes in scale, the δ18O data from whole-rock carbonates present fluctuant temperature results similar with well-studied composite δ18O curves of diagenetically-screened biogenic calcites, and are possibly acceptable as a paleotemperature proxy. The paleoclimate trends imply a cool global Callovian-Oxfordian transition, a mid-Oxfordian warming, a late Oxfordian cooling, a turbulent Kimmeridgian climate, a warm earliest Tithonian and rapid early Tithonian cooling event. The climate shift from the earliest Tithonian warmth to the middle early Tithonian cool climate was up to 8 °C decrease in some regions. These paleoclimate changes are greatly consistent with the eustatic sea-level changes, biological evolutions and paleoatmospheric CO2 reconstructions, and are recorded by coeval carbon isotope perturbations relating to the organic carbon accumulations in marine sediments. Coupled δ18O and δ13C chemostratigraphy evidence that higher temperatures lead to more rapid continental weathering, increased nutrient-rich runoff into the oceans, and intensified marine productivity, resulting in increased organic‑carbon burial and more positive δ13C values in limestones. The decrease in primary productivity and burial rates during cooling periods is, in turn, commonly accompanied by low δ13C values.

Paleogeographic reconstruction and sedimentary evolution of tidal-dominated estuarine depositional systems: Insights from the campanian M1 sandstone formation, Oriente Basin, Ecuador

The Oriente Basin is a back-arc basin located east of the Ecuadorian Andes in South America. Evidence suggests that during the Cretaceous period, the basin's margins received a terrigenous shallow marine sedimentation. Due to regional variations in accommodation and depositional controlling factors near a shoreline, the sedimentary environments in the fluvial-marine transitional zones exhibit considerable variability. In this study, we analyzed the sedimentological characteristics of the M1 Sandstone Formation unit (∼83 Ma-72 Ma), which comprises a set of ancient estuarine deposits preserved in the northern part of the basin. We quantified the impact of mixed hydrodynamic processes on the distribution of tidal-dominated estuarine facies and discussed the development conditions and evolutionary processes of an estuarine formation under the background of persistent transgression. Core, well log, and seismic data provide evidence for reconstructing the tidal-dominated estuarine environment. In the core section, we identified 14 lithofacies and 7 major facies association types. The frequent occurrence of sedimentary structures associated with tidal currents indicates that tidal processes extensively reworked the deposits. The spatial distribution trends of facies associations reveal the evolution of mixed hydrodynamic conditions dominated by tidal processes in the estuary and allow us to divide the M1 Sandstone Formation into four depositional periods: the initial development, rapid development, decline, and the post-infilling open coast tidal flat development periods. Furthermore, through a systematic analysis of hydrodynamic conditions and sediment distributions, we identified multiple depositional centers in the tidal-dominated estuary influenced by different hydrodynamic processes. These correspond to the upstream fluvial-dominated tidal point bar depositional region, the middle mixed-energy depositional interaction zone, and the downstream tidal-dominated tidal sand bar depositional region. In these regions, the substantial accumulation of sandy deposits, represented by tidal sand bars, reflects the high accommodation space characteristic of tidal-dominated estuaries. Our findings indicate that the slow subsidence of a broad and gently sloping coastal topography, stable material transport, and sea level change dominated by marine transgression ensured the necessary accommodation for the development of the estuary in the M1 Sandstone Formation. The sedimentological study of the M1 Sandstone Formation provides a case for understanding the sedimentary evolution in fluvial-marine transitional zones.

Gap filling of missing satellite data from MODIS and CMEMS for chlorophyll-a in the waters of Aceh, Indonesia

The motivation behind our study is to identify a robust method to enhance the accuracy of missing data, particularly chlorophyll-a data, which often goes undetected due to various factors. This study analyzes chlorophyll-a concentrations and sea level changes due to tides using three methods: Linear Interpolation, Fillgaps, and Modified Fillgaps. Two experiments were conducted: Experiment I involved random data removal (60% and 70%), and Experiment II combined sequential and random data removal (25% sequentially on the right, 35% and 45% randomly on the left). In Experiment I, the Modified Fillgaps method showed high correlation coefficients (up to 0.96) between original and reconstructed data, demonstrating its effectiveness in accurately filling significant data gaps. This method also exhibited low Root Mean Square Error and Mean Absolute Error values, confirming its predictive precision. In Experiment II, despite structured and realistic data loss patterns, the method maintained high correlation and low prediction errors, with low Normalized Root Mean Squared Error and Mean Absolute Percentage Error values, further validating its reliability. Additionally, the method excelled in two-dimensional chlorophyll-a maps, outperforming Linear Interpolation and Fillgaps methods in scenarios with 50% and 60% data loss, achieving higher correlation and lower prediction errors. These findings are crucial for environmental and climatological studies relying on satellite-derived data, confirming the Modified Fillgaps method as the most reliable and effective for handling significant data loss in chlorophyll-a map analyses. Future research should explore its application to other environmental data types and more complex data loss patterns.

Transdisciplinary Research Supports the Sustainability of Barrier Island Systems Threatened by Climate Change

AbstractThe management of developed barrier islands is often piece‐meal and reactionary despite the complex, dynamic nature of these systems, and sustainable practices will become increasingly difficult due to heightened pressures of climate change. Adaptation actions, including nature‐based solutions, need to be thoroughly evaluated prior to implementation to understand system‐wide impacts and avoid maladaptation. Anarde et al. (2024a), (https://doi.org/10.1029/2023ef003672), Anarde et al. (2024b), (https://doi.org/10.1029/2023ef004200) is the latest important contribution in a growing body of transdisciplinary research that more robustly evaluates the complex physical process‐and‐response relationship of barrier systems via sophisticated numerical modeling approaches that also interface with socioeconomic models to inform coastal management actions in response to mitigating coastal risk. This new research indicates the importance of coordinated system‐scale barrier island management, as strategies to reduce coastal hazard risk in one location will directly affect adjacent communities. Further, this work demonstrates that reducing barrier management interventions may actually promote barrier recovery and sustainability in the face of sea level rise. In addition, recent advances in the analysis and application of remotely sensed data from satellites and oblique aerial photography provide scientists an unprecedented opportunity to track coastal evolution over a wide range of spatial and temporal scales at minimal cost. As sea level rise and changing storm patterns challenge the sustainable management of barrier island systems, integrating these advanced, transdisciplinary tools will enable scientists and coastal practitioners to more thoroughly evaluate coastal adaptation options, efficiently invest limited resources to mitigate coastal hazard risk for communities, support healthy ecosystems, and reduce system‐wide impacts.

FEATURES OF THE LITHOLOGICAL STRUCTURE AND DEVELOPMENT OF RESERVOIR ROCKS AND HYDROCARBON RESERVOIRS IN THE MIDDLE DEVONIAN SEDIMENTS OF THE SOUTHERN PART OF THE TUZLIV DEPRESSION (DOBRUDJA FOREDEEP)

The aim of the work was to clarify the features of the lithological structure of the Middle Devonian sediments of the Zhovtoyarska-Tuzlivska and Biloliska-Zarichnenska prospective areas of the Dobrudja Foredeep and to determine its influence on the formation of reservoir rocks, traps and hydrocarbon reservoirs. The research was based on the results of geophysical research of wells (radioactive methods) in combination with fragmentary geological (lithological) data. As a result, 9 lithocycles of regressive nature were identified in the section for the first time (e-1 – e-5; g-1 – g-4). Each lithocycle is characterized by a two-membered structure and represents a separate productive horizon (PH). The lower parts of the latter are composed of porous and fractured reservoir rocks (limestones, dolomites, siltstones, sandstones), and the upper parts are composed of fluid-resistant packs (marls, anhydrites). It has been shown that cyclites are grouped into larger units (mesocyclites) of re- or progressive nature, which in different wells (in separate intervals) exhibit a certain similarity or difference in structure. Such spatial and age variability is caused, on the one hand, by the placement of wells in different facies zones of the sulfate-carbonate shelf, and on the other, by the processes of interaction of synsedimentary tectonic movements and paleoceanographic (sea level changes, etc.) factors. The consequence of this is the lateral lithological heterogeneity, which in the petrogeological aspect is manifested in the morphological features of the reservoirs and the character of the development of various types of reservoirs and ultimately determines, taking into account secondary rock changes, the prospects of specific productive horizons. Thus, for the Zhovtoyarska-Tuzlivska area, the vaulted trap is localized near borehole Zhovtoyarska-1 (e-1, e-2 productive horizons), according to other horizons it is fixed near borehole Zhovtoyarska-2. The development of lithological traps is predicted in e-1, e-3 and e-4 productive horizons, which is associated with the wedging of pore reservoirs in the direction from borehole Tuzlivska-2 to borehole Zhovtoyarska -2 and -1. For most productive horizons, the quality of reservoir rocks is expected to deteriorate in the same direction, which suggests the possibility of catagenetic screening of fluids. For the Biloliska-Zarichnenska area, along all productive horizons, trap vaults are localized near borehole Zarichnenska-1 or further south. The most capacious are the traps of horizons e-1, e-4 and e-5, composed mainly of pore-type collectors, the quality of which is low due to anhydritization. The best reservoir rocks are predicted in the Givetian sediments (g-2 – g-4 productive horizons) of borehole Zarichnenska -1.

Genome of Halimeda opuntia reveals differentiation of subgenomes and molecular bases of multinucleation and calcification in algae

Algae mostly occur either as unicellular (microalgae) or multicellular (macroalgae) species, both being uninucleate. There are important exceptions, however, as some unicellular algae are multinucleate and macroscopic, some of which inhabit tropical seas and contribute to biocalcification and coral reef robustness. The evolutionary mechanisms and ecological significance of multinucleation and associated traits (e.g., rapid wound healing) are poorly understood. Here, we report the genome of Halimeda opuntia, a giant multinucleate unicellular chlorophyte characterized by interutricular calcification. We achieve a high-quality genome assembly that shows segregation into four subgenomes, with evidence for polyploidization concomitant with historical sea level and climate changes. We further find myosin VIII missing in H. opuntia and three other unicellular multinucleate chlorophytes, suggesting a potential mechanism that may underpin multinucleation. Genome analysis provides clues about how the unicellular alga could survive fragmentation and regenerate, as well as potential signatures for extracellular calcification and the coupling of calcification with photosynthesis. In addition, proteomic alkalinity shifts were found to potentially confer plasticity of H. opuntia to ocean acidification (OA). Our study provides crucial genetic information necessary for understanding multinucleation, cell regeneration, plasticity to OA, and different modes of calcification in algae and other organisms, which has important implications in reef conservation and bioengineering.

Feedback mechanisms controlling Antarctic glacial-cycle dynamics simulated with a coupled ice sheet–solid Earth model

Abstract. The dynamics of the ice sheets on glacial timescales are highly controlled by interactions with the solid Earth, i.e., the glacial isostatic adjustment (GIA). Particularly at marine ice sheets, competing feedback mechanisms govern the migration of the ice sheet's grounding line (GL) and hence the ice sheet stability. For this study, we developed a coupling scheme and performed a suite of coupled ice sheet–solid Earth simulations over the last two glacial cycles. To represent ice sheet dynamics we apply the Parallel Ice Sheet Model (PISM), and to represent the solid Earth response we apply the 3D VIscoelastic Lithosphere and MAntle model (VILMA), which, in addition to load deformation and rotation changes, considers the gravitationally consistent redistribution of water (the sea-level equation). We decided on an offline coupling between the two model components. By convergence of trajectories of the Antarctic Ice Sheet deglaciation we determine optimal coupling time step and spatial resolution of the GIA model and compare patterns of inferred relative sea-level change since the Last Glacial Maximum with the results from previous studies. With our coupling setup we evaluate the relevance of feedback mechanisms for the glaciation and deglaciation phases in Antarctica considering different 3D Earth structures resulting in a range of load-response timescales. For rather long timescales, in a glacial climate associated with the far-field sea-level low stand, we find GL advance up to the edge of the continental shelf mainly in West Antarctica, dominated by a self-amplifying GIA feedback, which we call the “forebulge feedback”. For the much shorter timescale of deglaciation, dominated by the marine ice sheet instability, our simulations suggest that the stabilizing sea-level feedback can significantly slow down GL retreat in the Ross sector, which is dominated by a very weak Earth structure (i.e., low mantle viscosity and thin lithosphere). This delaying effect prevents a Holocene GL retreat beyond its present-day position, which is discussed in the scientific community and supported by observational evidence at the Siple Coast and by previous model simulations. The applied coupled framework, PISM–VILMA, allows for defining restart states to run multiple sensitivity simulations from. It can be easily implemented in Earth system models (ESMs) and provides the tools to gain a better understanding of ice sheet stability on glacial timescales as well as in a warmer future climate.

Scottish landform example: isolation basins of Arisaig

ABSTRACT An isolation basin is a geomorphological landform that enables the precise reconstruction of the former height and age of relative sea level. A series of isolation basins at different elevations within a small geographical area can provide a high-resolution record of the timing and magnitude of relative sea-level change. Arisaig, on the west coast of Scotland, provides the longest post-Last Glacial Maximum record of relative sea-level change in the UK, produced from the analysis of a series of 16 isolation basins. The records produced from these basins continue to provide important constraints that inform understanding of processes acting from local to global scales, such as glacial and climatic transitions, glacio-isostatic adjustment and global meltwater pulses.

Reconstructing the rapid transitions of ecosystems during the mid-late Holocene: A pollen record from Haixing wetland in Bohai Bay, North China

Vegetation in coastal regions is sensitive to climate and sea-level changes. However, currently there is still a lack of understanding about the stability of the Holocene coastal ecosystem and the rapid conversion processes of different coastal wetland ecosystems. In this study, the high-resolution vegetation succession history of the southwest coast of Bohai Bay during the mid-late Holocene was revealed, based on pollen analysis and REVEALS model, and the rate of vegetation change was estimated. Furthermore, the characteristics and mechanisms of different ecosystem changes were explored. The results indicate that there was a prolonged transition from shallow sea to lagoon before the formation of the Haixing wetland during the interval of 7500–4100 cal yr BP. The rate of watershed vegetation change increase significantly under the common influence of the 4.2 ka event and human activities, causing a regime shift in the mountain forest ecosystems and a decrease in landscape resilience. It was characterized by a substantial reduction in broad-leaved forests (from>30% to<5%), especially for Quercus (∼3%), which have not recovered to pre-event levels since the end of the 4.2 ka event. Since 3500 cal yr BP, the Haixing area was completely detached from the influence of the Bohai Sea, forming freshwater wetlands. The local vegetation rapidly shifted from alkali-tolerant communities that followed the sea retreat to freshwater marsh plant communities. During 2000–1100 cal yr BP, under the strong impact of human activities, the succession of forest and grassland communities in the basin became more frequent. The area of coastal salt marshes expanded, with salt-tolerant plant communities taking the absolute advantage. The wetland vegetation landscape became closer to the modern appearance. Overall, our study provides new evidence for understanding the rapid evolution of coastal ecosystems in East Asia influenced by a combination of climate, hydrology and humans. It will help guide the coastal regions in facing the challenges of future global climate changes.

The Main Controlling Factors of the Development and Extinction of ' Carbonate Factory '

Building upon the profound foundation of previous research on carbonate factories, this paper systematically organizes the classification system of carbonate factories and delves into the primary controlling factors of their demise, thereby providing a more precise portrayal of the diverse facets and intricate evolution of carbonate factories throughout geological history. Based on carbonate rock types, sedimentary environment characteristics, the dominant agents in the construction process, deposition and precipitation patterns, as well as oceanographic conditions, the carbonate factories are categorized into five major groups, each of which is comprehensively described. Furthermore, this paper summarizes six key controlling factors: fluctuations in nutrient levels, anoxic events, tectonic activities, massive inputs of terrestrial materials, mass extinctions of organisms, and significant changes in sea level. It delves into how these factors, acting either independently or synergistically, lead to the demise of carbonate factories, elaborating on the corresponding processes and mechanisms in detail.

Links between anhydrite precipitation and dolomitization during cycles of sea level change: Insights from the Late Jurassic Arab Formation, Abu Dhabi, United Arab Emirates

Despite extensive research in the field of evaporative dolomitization, the close link between anhydrite precipitation and dolomitization is still poorly explored within the context of sequence stratigraphy. This comprehensive diagenetic and sequence stratigraphic study of the Late Jurassic Arab Formation, Abu Dhabi, United Arab Emirates, provides important insights into the relationship between anhydrite precipitation and dolomitization within the 2nd, 3rd, and 4th orders of relative sea-level cycles. Initial good connectivity between the inner ramp and open sea during 2nd order late transgressive-early regression cycles accounts for the limestone-dominated lithology with limited anhydrite formation. Conversely, the following progressive 2nd order fall in the relative periodic restriction of the inner platform during 2nd order early regressive cycles (early highstand systems tracts, HST) caused seepage reflux dolomitization and the precipitation of scattered to pervasive anhydrite cement in the dolostones. Variations in the extent of dolomitization were controlled by the permeability and reactivity of the precursor limestones, resulting in the formation of what is known as dolomite fingers. The most laterally extensive dolomitization during late 2nd order regression resulted in the formation of microcrystalline dolostones with nodular and chickenwire anhydrite by a combination of evaporative sabkha pumping and the seepage reflux of lagoon brines. The δ1³C and δ1⁸O of calcite and dolomite reveal the influence of degree of restriction of the inner ramp, and related extent of seawater evaporation. The lower limestone-dominated interval (3rd order HST) is characterized by lower δ1³C values (+2.0‰ to +2.5‰) owing to periodic restriction of seawater circulation, which resulted in oxidation of organic matter during aging of the seawater. This study approach provides important insights into the genetic links between interbedded platform limestones, dolostones, and anhydrites, and hence a better understanding and prediction of reservoir quality distribution and compartmentalization.

Facies variability and depositional cyclicity in central Northern Switzerland: insights from new Opalinus Clay drill cores

The Opalinus Clay, a silty to sandy claystone formation, Early to Middle Jurassic (Toarcian and Aalenian) in age, has been selected as the host rock for deep subsurface disposal of radioactive waste in Switzerland. Over the past thirty years, numerous geotechnical, mineralogical, and sedimentological studies have been conducted on the Opalinus Clay within the framework of the Nagra (National Cooperative for the Disposal of Radioactive Waste) deep drilling campaigns and the Mont Terri Project, an international research program dedicated to the study of claystone. The present study aims to unravel the variability of the lateral and vertical facies of the Opalinus Clay in central Northern Switzerland and to place this variability in a regional and basinal context. Analyses of new cores drilled in central Northern Switzerland, including petrographic, mineralogical (X-ray diffraction, multi-mineral interpretation), geochemical (X-ray fluorescence), statistical (non-metric multidimensional scaling analysis), and bedding dip and azimuth data, shed new light on the depositional facies and the spatial and temporal variability of the Opalinus Clay. Petrographic descriptions encompass nine new drill cores using a revised subfacies/facies classification scheme based on texture (colour, grain size, bedding) and composition (mineralogy). Particularly, one new subfacies (SF6) is described and interpreted as mass-wasting deposits. The drill cores are correlated laterally using specific marker horizons. This correlation is achieved by combining thorough facies investigations with lithostratigraphy, biostratigraphy, and chemostratigraphy. Six to seven small coarsening-upward cycles and two long-term coarsening-upward sequences can be interpreted as regressive trends. The observed trends are influenced by the interplay between sediment supply, eustatic sea level change, synsedimentary subsidence, but also the palaeogeographic configuration in an epicontinental sea, provenance and delivery of sediments, current dynamics and climate change. Finally, combined results show that the current dynamics in the Opalinus Clay has been underestimated until now and new depositional models, including the occurrence of drift deposits, are discussed.

Reconciled estimation of Antarctic ice sheet mass balance and contribution to global sea level change from 1996 to 2021

AbstractThe Antarctic Ice Sheet (AIS) has been losing ice mass and contributing to global sea level rise (GSLR). Given its mass that is enough to cause ∼58 m of GSLR, accurate estimation of mass balance trend is critical for AIS mass loss monitoring and sea level rise forecasting. Here, we present an improved approach to reconciled solutions of mass balance in AIS and its regions from multiple contributing solutions using the input-out, altimetric, and gravimetric methods. In comparison to previous methods, such as IMBIE 2018, this approach utilizes an adaptive data aggregation window to handle the heterogeneity of the contributing solutions, including the number of solutions, temporal distributions, uncertainties, and estimation techniques. We improved the regression-based method by using a two-step procedure that establishes ensembled solutions within each method (input-output, altimetry, or gravimetry) and then estimates the method-independent reconciled solutions. For the first time, 16 contributing solutions from 8 Chinese institutions are used to estimate the reconciled mass balance of AIS and its regions from 1996 to 2021. Our results show that AIS has lost a total ice mass of ∼3213±253 Gt during the period, an equivalent of ∼8.9±0.7 mm of GSLR. There is a sustained mass loss acceleration since 2006, from 88.1±3.6 Gt yr−1 during 1996–2005 to 130.7±8.4 Gt yr−1 during 2006–2013 and further to 157.0±9.0 Gt yr−1 during 2014–2021. The mass loss signal in the West Antarctica and Antarctic Peninsula is dominant and clearly presented in the reconciled estimation and contributing solutions, regardless of estimation methods used and fluctuation of surface mass balance. Uncertainty and challenges remain in mass balance estimation in East Antarctica. This reconciled estimation approach can be extended and applied for improved mass balance estimation in the Greenland Ice Sheet and mountain glacier regions.

A noisy-input generalized additive model for relative sea-level change along the Atlantic coast of North America

A noisy-input generalized additive model for relative sea-level change along the Atlantic coast of North America

Depositional Environment and Ecological Response of Bioconstructions: A Case Study of Southern China (Guizhou Province) in Moscovian-Gzhelian.

From the late Carboniferous to the early Permian, multiple pulses of glaciation and deglaciation have been caused by the LPIA. The Pennsylvanian period experienced phases of recovery, proliferation, and decline, ultimately forming a reef system distinctly different from that of the Mississippian period. During the late Bashkirian to Moscovian, the metazoan reef experienced a limited resurgence, with reef predominantly formed by chaetetid developing in the United States, northern China, and Japan. During the Kasimovian to Gzhelian, the phylloid algal reef dominated the global reef systems. In the late Pennsylvanian, bioconstruction cases and paleoenvironmental proxies in southern Guizhou Province were studied to investigate the composition, recovery, and evolutionary processes of the bioconstructions as well as their response to environmental variations during this period. Several bioconstructions have been reported in the Lumazhai section of Houchang Town, Guizhou Province, southern China, from the Moscovian to the Gzhelian. The upper Carboniferous strata are well-preserved and continuously exposed. The continuous strata, abundant fossils, and diverse bioconstructions provide excellent research materials for exploring the mutual constraints between organisms and their environment. This study identified ten microfacies, whose vertical evolution indicated significant changes in the depositional environment related to relative sea-level fluctuations. Skeletal grains are widely present in these facies. Among them, foraminifera, algae, bryozoans, crinoids, and Tubiphytes are the most common and exhibit distinct distribution characteristics in various environments. Quantitative statistics, CCA and theoretical ecospace have been utilized to examine and interpret environmental impact factors. Quantitative analysis of their relative abundance and distribution patterns provides insights into the complex interactions between organisms and environmental factors. The relative abundances of different organisms and factors controlling their bioconstructions are influenced by relative sea-level changes. CCA analysis reveal that hydrodynamic conditions are the primary influencing factor. Variation trends in average tiering and motility reveal the characteristics of biological communities during environmental changes in phylloid algae and microbial bioconstructions. These bioconstructions are not directly correlated with changes in environmental factors, and the biological communities in phylloid algae mounds and biostromes exhibit similar organism compositions and ecological niches across different environments.

Steric Sea Level Rise and Relationships with Model Drift and Water Mass Representation in GFDL CM4 and ESM4

Abstract Density-driven steric seawater changes are a leading-order contributor to global mean sea level rise. However, inter-model differences in the magnitude and spatial patterns of steric sea level rise exist at regional scales and often emerge during the spin-up and pre-industrial control integrations of climate models. Steric sea level results from an eddy-permitting climate model, GFDL-CM4, are compared with a lower resolution counterpart, GFDL-ESM4. The results from both models are examined through basin-scale heat budgets and watermass analysis, and we compare the patterns of ocean heat uptake, redistribution, and sea level differ in ocean-only (i.e. OMIP) and coupled climate configurations. After correcting for model drift, both GFDL-CM4 and GFDL-ESM4 simulate nearly equivalent ocean heat content change and global sea level rise during the historical period. However, the GFDL-CM4 model exhibits as much as a 40% increase in surface ocean heat uptake in the Southern Ocean and subsequent increases in horizontal export to other ocean basins after bias correction. The results suggest regional differences in the processes governing Southern Ocean heat export, such as the formation of AAIW, SPMW, and gyre transport between the two models, and that sea level changes in these models cannot be fully bias-corrected. Since the process-level differences between the two models are evident in the preindustrial control simulations of both models, these results suggest that the control simulations are important for identifying and correcting sea-level related model biases.

Palaeoenvironment and bio-events of the Cretaceous sediments of the Cauvery Basin, India

The Cauvery Basin is an important rift margin basin on the east coast of India. Its long research history began in the mid-nineteenth century with the pioneering work of H. F. Blanford. While much of the Cretaceous succession in the basin is fault-controlled, some of the recorded events represent global sea level changes, especially in the mid-Cretaceous. Macrofossils (ammonites, bivalves, etc.) and foraminifera are abundant throughout, and there is an important occurrence of fossil wood and ‘log-grounds’ in the Turonian–Coniacian. The basin is subdivided into a series of sub-basins (known as depressions in earlier literature), which, in places, have their own distinctive depositional history. The results of our collective fieldwork have provided a re-assessment of the lithostratigraphy, biostratigraphy and the tectono-stratigraphical history of the Ariyalur outcrop. Three sedimentary units have been identified: the syn-rift Gondwana Group (of early Cretaceous age), the syn-rift Uttatur Group (of Albian to Coniacian age) and the post-rift Ariyalur Group (of Santonian to Maastrichtian age). Both microfossil and macrofaunal information have been integrated in order to construct a biostratigraphical framework for the basin and develop a tectono-stratigraphical model. Structures exposed onshore, which have occasionally been interpreted as Albian reefs, are thought to be irregularly shaped limestone olistoliths and olistostromes produced by significant intra-Cretaceous faulting and slumping within the basin.

Modeling cross-shore profile evolution in response to climate change: A case study for the Southwestern Black Sea Coast

Changes in wave climate and sea level as a result of global climate change cause significant effects on coastal morphology. Especially increasing wave heights, more frequent storms, and sea level rise (SLR) significantly alter the morphology of cross-shore profiles and diminish the security of coastal areas. In this study, profile surveys were carried out in two distinct regions along the Western Coast of the Black Sea, and the profile evolutions were analyzed using the XBeach numerical model. The XBeach model was executed using both its default parameters and the parameters derived from on-site measurements. This study was also conducted under the influence of hydrodynamic conditions (wave parameters) that vary according to the RCP4.5 and RCP8.5 climate scenarios, along with the effects of sea level rise (SLR), to analyze the potential impacts of climate change on profile evolution. The results indicated a linear relationship between the upper beach erosion and sea-level rise (SLR). The increased water level in front of the upper beach leads to greater erosion volume. The model results for the scenarios demonstrated moderate sensitivity to variations in offshore wave height, peak wave period, and storm duration, but were predominantly sensitive to accelerated sea level rise (SLR).

Sedimentological evidence of Late Pleistocene Shorelines in Oman

As the climate crisis intensifies, estimating sea-level rise will become increasingly relevant, in particular assessing changes in the relative sea level in different regions. One key to comprehending global sea-level changes is the study of past sea-level highstands. Many regional studies help refine the reconstruction of paleo sea levels globally. Thus far, the Middle East remains understudied.This paper presents evidence for Quaternary sea-level variations along the shores of the western Indian Ocean. Eight coastal outcrops along the northern and eastern coasts of Oman are presented in detail. The sedimentological evidence for sea-level highstands varies within the study area. However, in relation to recent sea-level conditions, all of these marine and beach deposits are now found well above the environments where such formations would typically form. Dating the timing of sea-level highstands remains a challenging task within the study area. In different studies, attempts to 14C date samples from that area were unsuccessful, as the time of sediment deposition lies beyond the dating limit of 14C, precluding a Holocene formation of these sediments. Thus, the sediments are regarded as deposits formed during Pleistocene sea-level highstands, presumably during MIS 5e. For some sections, optically stimulated luminescence dating could provide a solution, as igneous source rocks supply quartz and feldspar. This paper aims to localise eight sea-level related outcrops along the Omani coast and depict their potential for future work, which should include dating and elevation measurements. Through this, our work contributes to the ongoing effort to globally identify records of sea-level changes, as well as providing insights into the regional setting in Oman.

Changes in the Water Surface Level of the Baltic Sea from Satellite Altimetry and Gravity Missions

ABSTRACT Satellite altimetry provides high-accuracy geometrical measurements of sea level changes. We analyze altimetry time series representing sea surface height anomalies over the mean sea surface provided by the TOPEX/Poseidon, Jason-1, Jason-2, and Jason-3 satellite missions to estimate the annual rate of sea level rise. Then, we compare the results with satellite gravimetric data from GRACE and GRACE Follow-On missions and surface water temperature data, employing statistical analyses to examine the interrelationships and correlations between them. We carry out the main analyses for the period 2001–2021 with a division into 5-year periods for six different areas of the Baltic Sea. The altimetric results show that between 2001 and 2021, the water level of the Baltic Sea rose by 5.8 mm/year on average. About 72% of the changes detected by altimetry missions can be explained by satellite gravimetry from GRACE and GRACE Follow-On, which means that the mass component is responsible for most of the observed sea level change, whereas the remaining 28% can be greatly explained by thermal expansion due to the water temperature rise.