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The island sanctuary of Barrow Island on the edge of the inner North-West continental shelf of Australia holds significant environmental as well as Indigenous and colonial cultural value. Insights on past occupation dynamics, particularly in response to Post-Glacial sea-level rise, continue to emerge from analysis of archaeological assemblages. However, there is limited temporal and landscape information from the wider island with which to better contextualise the physical site formation history of these cultural records. We present a new, modelled Post-Glacial sea-level curve for the region and new geochronological and sedimentological data (including rare earth element and quartz microtextural data) from non-archaeological site contexts to help infer changes in the coastal environment. This new data provides new insights on the island's paleogeography and evolution since approximately 80 ka BP in the context of inherited Last Interglacial features and highly dynamic oceanographic processes. Ongoing physical weathering processes have influenced dune building and reworking, such that neither colour nor numeric age are reliable indicators of sediment compositional and textural maturity. The results continue to emphasise how the continued integration of the island's geological, sedimentological and archaeological records help to understand aspects of cultural site formation, as well as expose some of the limiting factors in our understanding of past and present island physical dynamics. Ministry of Education (MOE) National Research Foundation (NRF) Submitted/Accepted version This study was made possible through a Research Collaboration Award from the University of Western Australia, with additional funding provided from an Australian Research Council Discovery Early Career Award to IW (DE180100601). Archaeological data was collected by the Barrow Island Archaeological Project funded by an ARC Discovery Grant (DP130100802) 2013–2015 awarded to PV and team. Department of Biodiversity Conservation and Attractions, Chevron Australia and WA Oil are thanked for their logistical and personnel support in the field, as also are Mick O’Leary and Peter Kendrick. We acknowledge the support of Buurabalayji Thalanyji Aboriginal Corporation. We thank Dick Peltier for providing the ICE-7G_NA ice model and Kurt Lambeck and Anthony Purcell for providing the ANU-ICE ice model. The global ANU-ICE combination model used in this study was kindly provided by Holger Steffen. Tanghua Li is supported by the Singapore Ministry of Education Academic Research Fund MOE2019- T3-1-004 and MOE2018-T2-1-003, the National Research Foundation Singapore, and the Singapore Ministry of Education, under the Research Centers of Excellence initiative. The GIA modelling is conducted in part using the research computing facilities and/or advisory services offered by Information Technology Services, the University of Hong Kong. This work comprises Earth Observatory of Singapore contribution no. 424. The authors also acknowledge the facilities, and the scientific and technical assistance of Microscopy Australia at the Centre for Micro- scopy, Characterisation & Analysis, the University of Western Australia, a facility funded by the University, State and Commonwealth Govern- ments. Acknowledgement is given to Mark Basgall David Zeanah and David Glover of Sacramento University for use of artefact distribution maps; and to Mick O’Leary for the DEM image of the Chair (Loop Beach).

Holocene relative sea-level (RSL) data from far-field islands in the mid-Pacific have been used to validate the ice-melting histories of glacial isostatic adjustment (GIA) models. However, a lack of quality control in the reconstruction of RSL hinders the understanding of regional variability that can constrain ice-equivalent sea-level changes. Here, we present a standardised database of Holocene RSL data from five regions in the mid-Pacific (Cook Islands, Tuamotu Islands, Christmas (Kiritimati) Island, Gilbert Islands and Fiji). We categorised the data as high or low quality based on the susceptibility of samples to age and/or elevation errors. Of the 614 data points that were reviewed, 25% were rejected and 100 sea-level index points (SLIPs) were reinterpreted as limiting data. The new database consists of 141 SLIPs and 262 marine and 56 terrestrial limiting data points reconstructed from a variety of sea-level indicators (e.g., coral microatolls, mangrove peat, beachrock, and beach ridges), of which 71% provide high-quality constraints on RSL. The early to mid Holocene RSL evolution in the Cook Islands, Gilbert Islands and Fiji are poorly constrained due to a lack of high-quality SLIPs and limiting data during this period. The Tuamotu Islands provided the only record of early to mid Holocene evolution of RSL, indicating rapid RSL rise from between −22.9 m and −15.2 m at ∼9.0 ka to between −0.2 m and 0.5 m by ∼6.5 ka, at rates as high as 9.8 ± 5.1 mm/a, with a slowdown in the rate of RSL rise sometime between ∼8.2 ka and ∼6 ka. The Christmas (Kiritimati) Island record indicates stable RSL within ∼1.5 m of present-day levels over the past ∼6.6 ka. In the late Holocene, the Cook Islands record suggests a gradual fall in RSL over the past ∼2.9 ka at rates below 0.1 ± 4.3 mm/a. SLIPs at Fiji also indicate a slight fall in RSL at rates of less than 0.5 ± ∼4.4 mm/a at ∼4 ka, following which RSL fell from above 0.9 m at ∼3 ka to between −0.3 m and 0.6 m by ∼2.5– ∼2.1 ka. We highlight the importance of standardisation and quality control to critically evaluate the processes controlling RSL and validate GIA models. Indeed, the new standardised database has implications for the timing of the mid- Holocene highstand, which has been used to support the ICE-4G and ICE-7G_NA models. Due to the poor constraints of data in the mid-Pacific islands, particularly in the early Holocene, there remains no unique solution for a global ice-melting history. Ministry of Education (MOE) National Research Foundation (NRF) Published version Fangyi Tan, Tanghua Li, Je˛drzej Majewski, and Benjamin P. Horton are supported by the Singapore Ministry of Education Academic Research Fund MOE2019-T3-1-004 and MOET2EP50120-0007, the National Research Foundation Singapore, and the Singapore Ministry of Education, under the Research Centers of Excellence initiative.

Analyses of glacial isostatic adjustment (GIA) and deglacial relative sea-level (RSL) change in the Russian Arctic deliver important insights into the Earth's viscosity structure and the deglaciation history of the Eurasian ice sheet complex. Here, we validate the 1D GIA models ICE-6G_C (VM5a) and ICE-7G_NA (VM7) and select new 3D GIA models in the Russian Arctic against a quality-controlled deglacial RSL database of >500 sea-level data points from 24 regions. Both 1D models correspond to the RSL data along the southern coast of the Barents Sea and Franz Josef Land from ∼11 ka BP to present but show notable misfits (>50 m at 10 ka BP) with the White Sea data. We find 3D model predictions of deglacial RSL resolve most of the misfits with the observed data for the White Sea while retaining comparable fits in other regions of the Russian Arctic. Our results further reveal: (a) RSL in the western Russian Arctic is sensitive to elastic lithosphere with lateral thickness variation and 3D viscosity structure in the upper mantle; and (b) RSL in the whole Russian Arctic is less sensitive to 3D viscosity structure in the lower mantle compared to the upper mantle. The 3D models reveal a compromise in the upper mantle between the background viscosity and scaling factor to best fit the RSL data, which needs to be considered in future 3D GIA studies. Ministry of Education (MOE) National Research Foundation (NRF) Published version Tanghua Li, Timothy A. Shaw, and Benjamin P. Horton are supported by the Singapore Ministry of Education Academic Research Fund MOE2019 -T3-1-004, MOE2018-T2-1-030 and MOE-T2EP50120-0007, the National Research Foundation Singapore, and the Singapore Ministry of Education, under the Research Centers of Excellence initia- tive. The research of W. Richard Peltier at Toronto is supported by NSERC discov- ery Grant A9627. The work of Alisa Baranskaya was supported by the Russian Science Foundation Grant 22-77-10,031; she used equipment and facilities obtained within the State Budget Theme АААА- А16-116032810055-0. The FE calcula- tion was performed with the ABAQUS package from Hibbitt, Karlsson and Sorensen Inc. This research is conducted in part using the research computing facilities and/or advisory services offered by Information Technology Services, the University of Hong Kong. The authors acknowledge HOLSEA and PALSEA, working groups of the International Union for Quaternary Sciences (INQUA) and Past Global Changes (PAGES), which in turn received support from the Swiss Academy of Sciences and the Chinese Academy of Sciences. This article is a contribution to International Geoscience Program (IGCP) Project 639, “Sea-Level Changes from Minutes to Millennia.” We express our gratitude to Muhammad Hadi Ikhsan for support with the graphics. This work is Earth Observatory of Singapore contribution 435.

Determining the rates, mechanisms, and geographic variability of relative sea-level (RSL) change following the Last Glacial Maximum (LGM) provides insight into the sensitivity of ice sheets to climate change, the response of the solid Earth and gravity field to ice-mass redistribution, and constrains statistical and physical models used to project future sea-level rise. To do so in a scientifically robust way requires standardized datasets that enable broad spatial comparisons that minimize bias. As part of a larger goal to develop a unified, spatially-comprehensive post-LGM global RSL database, in this special issue we provide a standardized global synthesis of regional RSL data that resulted from the first ‘Geographic variability of HOLocene relative SEA level (HOLSEA)’ meetings in Mt Hood, Oregon (2016) and St Lucia, South Africa (2017). The HOLSEA meetings brought together sea-level researchers to agree upon a consistent protocol to standardize, interpret, and incorporate realistic uncertainties of RSL data. This special issue provides RSL data from ten geographical regions including new databases from Atlantic Europe and the Russian Arctic and revised/expanded databases from Atlantic Canada, the British Isles, the Netherlands, the western Mediterranean, the Adriatic, Israel, Peninsular Malaysia, Southeast Asia, and the Indian Ocean. In total, the database derived from this special issue includes 5634 (5290 validated) index (n = 3202) and limiting points (n = 2088) that span from ∼20,000 years ago to present. Progress in improving the standardization of sea-level databases has also been accompanied by advancements in statistical and analytical methods used to infer spatial patterns and rates of RSL change from geological data that have a spatially and temporally sparse distribution and geochronological and elevational uncertainties. This special issue marks the inception of a unified, spatially-comprehensive post-LGM global RSL database. Ministry of Education (MOE) National Research Foundation (NRF) Published version NSK and BPH were funded by the Singapore Ministry of Edu- cation Academic Research Fund MOE2018-T2-1-030, the National Research Foundation Singapore, and the Singapore Ministry of Education, under the Research Centres of Excellence initiative. This work is Earth Observatory of Singapore contribution 252. AR ac- knowledges the Institutional Strategy of the University of Bremen, funded by the German Excellence Initiative (ABPZuK-03/2014) and the SEASCHANGE (RO-5245/1-1) from the Deutsche For- schungsgemeinschaft (DFG) as part of the Special Priority Program (SPP)-1889 00Regional Sea Level Change and Society”. TET ac- knowledges support from the Paleo Perspectives on Climate Change program of the US National Science Foundation (OCE- 1502588). We thank Maren Bender for her help in preparing the comparison of data from Southeast Asia. This article is a contribu- tion to PALSEA (Palaeo-Constraints on Sea-Level Rise) and Inter- national Geoscience Program (IGCP) Project 639, “Sea Level Change from Minutes to Millennia”.

Proxy reconstructions of estuarine evolution provide perspectives on regional to global environmental changes, including relative sea-level changes, climatic changes, and agricultural developments. Here, we present a new benthic foraminiferal record along with δ13C and C/N, and lithological data from a sediment core in the Pearl River estuary (Lingding Bay) adjacent to the South China Sea. The core has relatively thick Holocene sediments (>40 m) due to its location in the paleo-valley of the Pearl River. The lithologic and foraminiferal record reveal an evolution in paleoenvironment from fluvial, inner estuary to middle estuary between 11300 and 8100 cal a BP in response to rapid sea-level rise. δ13C and C/N data indicate high freshwater discharge from 10500 to 8100 cal a BP driven by a strong Asian monsoon. The middle Holocene (8100 - 3300 cal a BP) sediment is absent in the core due to subaqueous erosion resulting from the unique geomorphology of the Pearl River Delta. In the late Holocene from 3300 cal a BP to the present, the lithology and foraminiferal assemblages suggest a further evolution from outer estuary, middle estuary channel, to middle estuary shoal, resulting from deltaic progradation under stable relative sea levels. In the last 2000 years, δ13C and C/N values reveal the intensive development of agriculture coupled with the reduction of freshwater input derived from a weakening Asian monsoon. Ministry of Education (MOE) National Research Foundation (NRF) Accepted version This work was supported by the National Natural Science Foundation of China (NSFC: 41276079). Professor Huang Kangyou was thanked for his assistance in improving the English. This work was supported by the following grants: the National Natural Science Foundation of China (NSFC: 41661144003). NSK and BPH were funded by the Singapore Ministry of Education Academic Research Fund MOE2018-T2-1-030, the National Research Foundation Singapore, and the Singapore Ministry of Education, under the Research Centres of Excellence initiative. This article is a contribution to PALSEA2 (Palaeo-Constraints on Sea-Level Rise) and International Geoscience Program (IGCP) Project 639, “Sea Level Change from Minutes to Millennia”. This work is Earth Observatory of Singapore contribution 243.

The coast of China is located in the far-field of past large ice sheets, and therefore relative sea-level (RSL) data from this region have been used to infer sea-level equivalent changes during the Holocene using geophysical models of the glacial-isostatic adjustment (GIA) process. However, there are known misfits between GIA models and Holocene RSL data along the coast of China. For example, GIA model predictions compared to RSL data from China and the Malay-Thailand peninsula show misfits in the amplitude and timing of maximum RSL (highstand) and temporal variations of RSL from the highstand to the present. Furthermore, two different preferred viscosity profiles were recognized between China and the Malay-Thai Peninsula, suggesting the presence of lateral (3D) variations in mantle viscosity across this region. These previous findings lead to several questions: 1) Are the interpretations of RSL proxies and ages robust? 2) Do 3D GIA models improve the fit compared to 1D models? and 3) Are other local- to regional-scale processes significantly influencing RSL on the China coast?We aim to answer these questions by completing an updated, quality-controlled database of Holocene RSL data and integrating it into a spatio-temporal empirical hierarchical model (STEHM) and comparing the results to GIA models. Here, we use standardized protocols to present a preliminary compilation of Holocene RSL data (105 index points and 134 limiting points) from the southern China coast, which extends geographically from 119.19°N (Fuzhou city of Fujian Province) to 111.82°N (Xisha Islands) and 21.82 °E (Qinzhou city of Guanxi Province) to 25.22 °E (Putian city of Fujian Province). Sedimentary (salt marsh, mangrove, tidal flat, lagoon), geomorphic (Chenier ridge, beach rock), fixed biological (oyster), and coral indicators comprise the majority of RSL data in the compilation for the last 12 ka. The database is divided into sub-regions to investigate the influence of tectonics and GIA on RSL.We apply the STEHM to the preliminary dataset to estimate the magnitudes and rates of RSL, and compare them to the radially symmetric (1D) ICE-6G_C (VM5a) GIA model pairing and an analysis of the sensitivity of the region to 3D viscosity structure. We find that sub-regional variability (i.e., spatial variability over a shorter spatial scale than the long-wavelength GIA signal) is observed throughout the Holocene. This spatial pattern suggests there is strong influence of local- to regional-scale processes causing RSL to vary from GIA model predictions because no data from sub-regions most sensitive to 3D viscosity structure (e.g., Bohai Bay) were included in these model runs. This preliminary analysis lays the groundwork to assess the potential influence of local-scale processes, such as sediment compaction and tidal range change, as well as regional impacts from tectonic vertical motion.

Holocene relative sea-level (RSL) records from regions distal from ice sheets (far-field) are commonly characterized by a mid-Holocene highstand, when RSL reached higher than present levels. The magnitude and timing of the mid-Holocene highstand varies spatially due to hydro-isostatic processes including ocean syphoning and continental levering. While there are open questions regarding the timing, magnitude and source of ice-equivalent sea level in the middle to late Holocene.Here, we compare Glacial Isostatic Adjustment (GIA) model predictions to a standardized database of sea-level index points (SLIPs) from Southeast Asia where we have near-complete Holocene records. The database has more than 130 SLIPs that span the time period from ~9.5 ka BP to present. We investigate the sensitivity of mid-Holocene RSL predictions to GIA parameters, including the lateral lithospheric thickness variation, mantle viscosity (both 1D and 3D), and deglaciation history from different ice sheets (e.g., Laurentide, Fennoscandia, Antarctica).We compute gravitationally self-consistent RSL histories for the GIA model with time dependent coastlines and rotational feedback using the Coupled Laplace-Finite Element Method. The preliminary results show that the timing of the highstand is mainly controlled by the deglaciation history (ice-equivalent sea level), while the magnitude is dominated by Earth parameters (e.g., lithospheric thickness, mantle viscosity). We further investigate whether there is meltwater input during middle to late Holocene and whether the RSL records from Southeast Asia can reveal the meltwater source, like Antarctica.

Rising global sea level, a consequence of climate change, results from an increase in the world ocean’s water volume and mass. Recent climate warming is responsible for producing the highest rate of global average sea-level rise of the past few millennia, and this rate will accelerate through the 21st century and beyond, exposing low-lying islands and coastal regions to significant flood risks. The flood risks can be compounded or diminished locally because changes in sea level are not uniform. In this review, we briefly discuss ice sheets as drivers of global and local sea levels, and how they could evolve under modern climate change. We underline some of the impacts of sea level change on coastal communities, and emphasize that local sea-level projections can be very different from estimates of the global average.

Sea-level budgets account for the contributions of processes driving sea-level change, but are predominantly focused on global-mean sea level and limited to the 20th and 21st centuries. Here we estimate site-specific sea-level budgets along the U.S. Atlantic coast during the Common Era (0–2000 CE) by separating relative sea-level (RSL) records into process-related signals on different spatial scales. Regional-scale, temporally linear processes driven by glacial isostatic adjustment dominate RSL change and exhibit a spatial gradient, with fastest rates of rise in southern New Jersey (1.6 ± 0.02 mm yr−1). Regional and local, temporally non-linear processes, such as ocean/atmosphere dynamics and groundwater withdrawal, contributed between −0.3 and 0.4 mm yr−1 over centennial timescales. The most significant change in the budgets is the increasing influence of the common global signal due to ice melt and thermal expansion since 1800 CE, which became a dominant contributor to RSL with a 20th century rate of 1.3 ± 0.1 mm yr−1., Sea-level rise is an important part of climate change, but most sea-level budgets are global and cannot capture important regional changes. Here the authors estimate sea-level budgets along the U.S. Atlantic coast, finding a faster rate of rise during the 20th century than any time in the past 2000 years.

We quantify GIA prediction uncertainties of 250 1D and 3D glacial isostatic adjustment (GIA) models through comparisons with deglacial relative sea‐level (RSL) data from North America and rate of vertical land motion ( urn:x-wiley:00948276:media:grl60497:grl60497-math-0001) and gravity rate of change ( urn:x-wiley:00948276:media:grl60497:grl60497-math-0002) from GNSS and GRACE data, respectively. Spatially, the size of the RSL uncertainties varies across North America with the largest from Hudson Bay and near previous ice margins along the northern Atlantic and Pacific coasts, which suggests 3D viscosity structure in the lower mantle and laterally varying lithospheric thickness. Temporally, RSL uncertainties decrease from the Last Glacial Maximum to present except for west of Hudson Bay and the northeastern Pacific coast. The uncertainties of both these regions increase from 30 to 45 m between 15 and 11 ka BP, which may be due to the rapid decrease of surface loading at that time. Present‐day urn:x-wiley:00948276:media:grl60497:grl60497-math-0003 and urn:x-wiley:00948276:media:grl60497:grl60497-math-0004 uncertainties are largest in southwestern Hudson Bay with magnitudes of 2.4 mm/year and 0.4 μGal/year, mainly due to the 3D viscosity structure in the lower mantle. Ministry of Education (MOE) National Research Foundation (NRF) Published version We thank Donald Argus and an anonymous reviewer for their very constructive comments, which have helped to improve the manuscript. Patrick Wu received GRF grant 17315316 from the Hong Kong Research Grants Council. Tanghua Li and Benjamin P. Horton are supported by the Singapore Ministry of Education Academic Research Fund MOE2019‐T3‐1‐004 and MOE2018‐T2‐1‐030, the National Research Foundation Singapore, and the Singapore Ministry of Education, under the Research Centers of Excellence initiative. Hansheng Wang is funded by the National Key R & D Program of China (2017YFA0603103) and National Natural Science Foundation of China (41431070 and 41974009). The research of W.R. Peltier at Toronto is supported by NSERC discovery grant A9627. The FE calculation was performed with the ABAQUS package from Hibbitt, Karlsson, and Sorensen Inc. This research is conducted in part using the research computing facilities and/or advisory services offered by Information Technology Services, the University of Hong Kong. This article is a contribution to PALSEA (Palaeo‐Constraints on Sea‐Level Rise), HOLSEA, and International Geoscience Program (IGCP) Project 639, “Sea‐Level Changes from Minutes to Millennia”. This work is Earth Observatory of Singapore contribution 293. The mean GIA signals of RSL, urn:x-wiley:00948276:media:grl60497:grl60497-math-0076, and urn:x-wiley:00948276:media:grl60497:grl60497-math-0077 with 1σ, 2σ, and 3σ uncertainties are provided for downloading in DR‐NTU (Data) with open access (https://doi.org/10.21979/N9/26AY8H). The deglacial RSL data, observed GNSS data used in this study are from the supplementary information of the corresponding references (with link) that are listed in the References List: Engelhart & Horton, 2012; Engelhart et al., 2015; Hawkes et al., 2016; Khan et al., 2017; Love et al., 2016; Peltier et al., 2015; Vacchi et al., 2018.

Sea-level rise projections and knowledge of their uncertainties are vital to make informed mitigation and adaptation decisions. To elicit projections from members of the scientific community regarding future global mean sea-level (GMSL) rise, we repeated a survey originally conducted five years ago. Under Representative Concentration Pathway (RCP) 2.6, 106 experts projected a likely (central 66% probability) GMSL rise of 0.30–0.65 m by 2100, and 0.54–2.15 m by 2300, relative to 1986–2005. Under RCP 8.5, the same experts projected a likely GMSL rise of 0.63–1.32 m by 2100, and 1.67–5.61 m by 2300. Expert projections for 2100 are similar to those from the original survey, although the projection for 2300 has extended tails and is higher than the original survey. Experts give a likelihood of 42% (original survey) and 45% (current survey) that under the high-emissions scenario GMSL rise will exceed the upper bound (0.98 m) of the likely range estimated by the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, which is considered to have an exceedance likelihood of 17%. Responses to open-ended questions suggest that the increases in upper-end estimates and uncertainties arose from recent influential studies about the impact of marine ice cliff instability on the meltwater contribution to GMSL rise from the Antarctic Ice Sheet. Ministry of Education (MOE) National Research Foundation (NRF) Published version Sea-level rise projections and knowledge of their uncertainties are vital to make informed mitigation and adaptation decisions. To elicit projections from members of the scientific community regarding future global mean sea-level (GMSL) rise, we repeated a survey originally conducted five years ago. Under Representative Concentration Pathway (RCP) 2.6, 106 experts projected a likely (central 66% probability) GMSL rise of 0.30–0.65 m by 2100, and 0.54–2.15 m by 2300, relative to 1986–2005. Under RCP 8.5, the same experts projected a likely GMSL rise of 0.63–1.32 m by 2100, and 1.67–5.61 m by 2300. Expert projections for 2100 are similar to those from the original survey, although the projection for 2300 has extended tails and is higher than the original survey. Experts give a likelihood of 42% (original survey) and 45% (current survey) that under the high-emissions scenario GMSL rise will exceed the upper bound (0.98 m) of the likely range estimated by the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, which is considered to have an exceedance likelihood of 17%. Responses to open-ended questions suggest that the increases in upper-end estimates and uncertainties arose from recent influential studies about the impact of marine ice cliff instability on the meltwater contribution to GMSL rise from the Antarctic Ice Sheet.

Last millennium relative sea-level (RSL) changes along the U.S. Atlantic coast are spatially variable. Glacial isostatic adjustment (GIA) has been a significant driving factor in RSL rise during the last millennium, producing maximum rates of vertical land motion in the mid-Atlantic region due to its proximity to the margin of the former Laurentide Ice Sheet. However, there is uncertainty surrounding the influence of other regional and local processes on RSL changes such as ocean and atmosphere circulation dynamics; gravitational, rotational, and deformational signals associated with ice mass and distribution changes; sediment compaction; and tidal range change.Here, we examined the high spatial density of high-resolution RSL records along a ~200 km stretch of coastline from New York City to southern New Jersey to distinguish between local, regional, and global scale drivers. We produced a new high-resolution (decimeter vertical, decadal temporal) RSL record of the last millennium in northern New Jersey and integrated it into an updated global database of instrumental and proxy sea-level records of the Common Era. We used a spatiotemporal empirical hierarchical model to estimate past RSL and rates of RSL change and their associated uncertainties in the context of broader regional changes by decomposing the records into global, regional linear, regional non-linear, and local components.We found that RSL in northern New Jersey continuously rose over the last 1000 years at a rate of 1.2 ± 0.2 mm/yr (2σ) from 1000 to 1700 CE before increasing to 1.3 ± 0.7 mm/yr from 1700-1800 CE to 1.8 ± 0.6 mm/yr from 1800-1900 CE to 3.0 ± 0.6 mm/yr from 1900-2000 CE. Most of the RSL rise during the past 1000 years is attributed to regional-scale linear processes that we interpret primarily as GIA. The linear component of the RSL records exhibits a north to south gradient, with a greater contribution of RSL rise in southern New Jersey and a smaller contribution in New York City. The regional-scale non-linear contribution from the records have a magnitude

Determining the rates, mechanisms and geographic variability of sea-level change is a priority science question for the next decade of ocean research. To address these research priorities, the HOLocene SEA-level variability (HOLSEA) working group is developing the first standardized global synthesis of Holocene relative sea-level data to: (1) estimate the magnitudes and rates of global mean sea-level change during the Holocene; and (2) identify trends in spatial variability and decipher the processes responsible for geographic differences in relative sea-level change.Here we present the efforts of the working group to compile the database, which includes over 12,000 sea-level index points and limiting data from a range of different indicators across seven continents from the Last Glacial Maximum to present. We follow a standard protocol that incorporates full consideration of vertical and temporal uncertainty for each sea-level index point, including uncertainties associated with the relationship of each indicator to past sea-level and the methods used to date each indicator. We highlight important challenges overcome to aggregate the standardized global synthesis, and discuss those that still remain. Finally. we apply a spatio-temporal empirical hierarchical statistical model to the database to estimate global sea-level variability and spatial patterns in relative sea level and its rates of change, and consider their driving mechanisms. Long-term, this effort will enhance predictions of 21st century sea-level rise, and provide a vital contribution to the assessment of natural hazards with respect to sea-level rise.

Proxy reconstructions of estuarine evolution provide perspectives on regional to global environmental changes, including relative sea-level changes, climatic changes, and agricultural developments. Although there are studies of the Holocene sedimentary processes in the Pearl River estuary, the understanding of early Holocene sedimentation in unknown due to limited preservation.Here, we present a new record of lithological, benthic foraminiferal, and geochemical (δ13C and C/N) change from a sediment core in the west shoal of the modern Lingding Bay along a paleo-valley. The lithologic and foraminiferal record reveal the transgressive evolution from fluvial, inner estuary to middle estuary in the early Holocene between 11300 and 8100 cal a BP in response to rapid sea-level rise. δ13C and C/N data indicate high freshwater discharge from 10500 to 8100 cal a BP driven by a strong Asian monsoon. The middle Holocene (8100 - 3300 cal a BP) sediment is absent in this core and others in the northward of the Lingding Bay. Seismic profiles reveal a tidal ravinement surface across Lingding Bay, which contributed to subaqueous erosion on the mid-Holocene sedimentation hiatus, might be resulted from unique geomorphology of the Pearl River Delta. In the late Holocene (3300 cal a BP to the present), the lithology and foraminiferal assemblages suggest further regressive evolution from outer estuary, middle estuary channel, to middle estuary shoal due to deltaic progradation under stable relative sea levels. In the last 2000 years, δ13C and C/N values reveal the intensive development of agriculture coupled with the reduction of freshwater input derived from a weakening Asian monsoon. Our study illustrates the interaction of Asian monsoon and sea-level changes within the Pearl River estuary landform and their impact on Holocene sedimentary processes.

Sea-level rise projections and knowledge of their uncertainties are vital to make informed mitigation and adaptation decisions. To elicit expert judgments from members of the scientific community regarding future global mean sea-level (GMSL) rise and its uncertainties, we repeated a survey originally conducted five years ago. Under Representative Concentration Pathway (RCP) 2.6, 106 experts projected a likely (at least 66% probability) GMSL rise of 0.30–0.65 m by 2100, and 0.54–2.15 m by 2300, relative to 1986–2005. Under RCP 8.5, the same experts projected a likely GMSL rise of 0.63–1.32 m by 2100, and 1.67–5.61 m by 2300. Expert projections for 2100 are similar to those from the original survey, although the projection for 2300 has extended tails and is higher than the original survey. Experts give a likelihood of 42% (original survey) and 45% (current survey) that under the high emissions scenario GMSL rise will exceed the upper bound (0.98 m) of the likely (i.e. an exceedance probability of 17%) range estimated by the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Responses to open-ended questions suggest that the increases in upper-end estimates and uncertainties arose from recent influential studies about the impact of marine ice cliff instability on the meltwater contribution to GMSL rise from the Antarctic Ice Sheet.

Foraminifera from salt-marsh environments have been used extensively in quantitative relative sea-level reconstructions due to their strong relationship with tidal level. However, the influence of temporal and spatial variability of salt-marsh foraminifera on quantitative reconstructions remains unconstrained. Here, we conducted a monitoring study of foraminifera from four intertidal monitoring stations in New Jersey from high marsh environments over three years that included several extreme weather (temperature, precipitation, and storm surge) events. We sampled four replicates from each station seasonally (four times per year) for a total of 188 samples. The dead foraminiferal assemblages were separated into four site-specific assemblages. After accounting for systematic trends in changes in foraminifera over time among stations, the distribution of foraminiferal assemblages across monitoring stations explained ~87% of the remaining variation, while ~13% can be explained by temporal and/or spatial variability among the replicate samples. We applied a Bayesian transfer function to estimate the elevation of the four monitoring stations. All samples from each station predicted an elevation estimate within a 95% uncertainty interval consistent with the observed elevation of that station. Combining samples into replicate- and seasonal-aggregate datasets decreased elevation estimate uncertainty, with the greatest decrease in aggregate datasets from Fall and Winter. Information about the temporal and spatial variability of modern foraminiferal distributions was formally incorporated into the Bayesian transfer function through informative foraminifera variability priors and was applied to a Common Era relative sea-level record in New Jersey. The average difference in paleomarsh elevation estimates and uncertainties using an informative vs uninformative prior was minimal (

The rate of relative sea-level (RSL) rise at Sandy Hook, NJ (4.0 ± 0.5 mm/yr) was higher than The Battery, NY (3.0 ± 0.3 mm/yr) from 1900 to 2012 despite being separated by just 26 km. The difference cannot be explained by differential glacial isostatic adjustment (GIA; 1.4 ± 0.4 and 1.3 ± 0.4 mm/yr RSL rise, respectively) alone. We estimate the contribution of sediment compaction to subsidence at Sandy Hook using high-resolution grain size, percent organic matter, and porosity data from three upper Quaternary (≤13,350 cal yr) cores. The organic matter content (

The persistence of coastal marsh is dependent on its ability to maintain elevation relative to sea level, particularly for marshes experiencing high rates of shoreline erosion due to wave-attack, storms, and sea level rise. Sediments eroded at the marsh edge are either delivered onto the marsh platform or into the estuary, the latter resulting in a net loss of marsh sediments and soil carbon. Knowledge on the timing, pattern, and quantity of sediment deposition versus shoreline erosion along the marsh-estuary interface is critical for evaluating the overall health and vulnerability of coastal marshes to future scenarios of sea level rise and for estimating sediment budgets. Here we examined marsh shoreline erosion and sediment deposition for marsh sites experiencing a range of shoreline erosion rates and different levels of wind-wave exposure within the Grand Bay National Estuarine Research Reserve and Wildlife Refuge in Mississippi. We developed a method for calculating an erosion-deposition sediment budget using marsh elevation profiles, shoreline erosion rate, and sediment deposition measurements. Sediment budgets were calculated at four sites with varying shoreline erosion rates. Much of the sediment eroded at the marsh edge can be accounted for as marsh platform deposition, except at the most erosive site, suggesting a possible erosion threshold where eroded sediment mass is greater than platform deposition. Consistent with other studies of marsh creeks, sediment delivery to the marsh platform appears to be largely driven by wave climate. These data suggest that for erosive bay-estuarine shorelines, sediment delivered into the marsh is largely concentrated near the marsh shoreline, although shoreline erosion does not always result in a net loss of sediments from the marsh system in either decadal or annual assessments.

Marine inundation associated with the 5 to 8 m storm surge of Typhoon Haiyan in 2013 left overwash sediments inland on the coastal plains of the northwestern shores of Leyte Gulf, Philippines. The Haiyan overwash deposit provides a modern sedimentary record of storm surge deposition from a Category 5 landfalling typhoon. We studied overwash sediments at two locations that experienced similar storm surge conditions but represent contrasting sedimentological regimes, namely a siliciclastic coast and a mixed siliciclastic-carbonate coast. The contrasting local geology is significantly reflected in the differences in sediment grain size, composition and sorting at the two sites. The Haiyan overwash sediments are predominantly sand and silt and can be traced up to ~ 1.6 km inland, extending farther beyond the previously reported < 300 m inland limit of sedimentation. Sites with similar geology, topographic relief, and overland flow conditions show significant spatial variability of sediment thickness and inland extent. We infer that other local factors such as small-scale variations in topography and the type of vegetation cover might influence the spatial distribution of overwash sediments. The Haiyan overwash deposits exhibit planar stratification, a coarsening upward sequence, a non-systematic landward fining trend, and a sharp depositional (rarely erosional) basal contact with the underlying substrate. Overall, the Haiyan deposits have sedimentologic and stratigraphic characteristics that show a hybrid signature common to both storm and tsunami deposits. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore) Published version

Comparisons of pre-earthquake and post-earthquake microfossils in tidal sequences are accurate means to measure coastal subsidence during past subduction earthquakes, but the amount of subsidence is uncertain, because the response times of fossil taxa to coseismic relative sea-level (RSL) rise are unknown. We measured the response of diatoms and foraminifera to restoration of a salt marsh in southern Oregon, USA. Tidal flooding following dike removal caused an RSL rise of ∼1 m, as might occur by coseismic subsidence during momentum magnitude (M w ) 8.1–8.8 earthquakes on this section of the Cascadia subduction zone. Less than two weeks after dike removal, diatoms colonized low marsh and tidal flats in large numbers, showing that they can record seismically induced subsidence soon after earthquakes. In contrast, low-marsh foraminifera took at least 11 months to appear in sizeable numbers. Where subsidence measured with diatoms and foraminifera differs, their different response times may provide an estimate of postseismic vertical deformation in the months following past megathrust earthquakes.

We present a Holocene relative sea-level (RSL) database for the Caribbean region (5°N to 25°N and 55°W to 90°W) that consists of 499 sea-level index points and 238 limiting dates. The database was compiled from multiple sea-level indicators (mangrove peat, microbial mats, beach rock and acroporid and massive corals). We subdivided the database into 20 regions to investigate the influence of tectonics and glacial isostatic adjustment on RSL. We account for the local-scale processes of sediment compaction and tidal range change using the stratigraphic position (overburden thickness) of index points and paleotidal modeling, respectively. We use a spatio-temporal empirical hierarchical model to estimate RSL position and its rates of change in the Caribbean over 1-ka time slices. Because of meltwater input, the rates of RSL change were highest during the early Holocene, with a maximum of 10.9 ± 0.6 m/ka in Suriname and Guyana and minimum of 7.4 ± 0.7 m/ka in south Florida from 12 to 8 ka. Following complete deglaciation of the Laurentide Ice Sheet (LIS) by ∼7 ka, mid-to late-Holocene rates slowed to

Mangroves under sea level rise The rate of sea level rise has doubled from 1.8 millimeters per year over the 20th century to ∼3.4 millimeters per year in recent years. Saintilan et al. investigated the likely effects of this increasing rate of rise on coastal mangrove forest, a tropical ecosystem of key importance for coastal protection (see the Perspective by Lovelock). They reviewed data on mangrove accretion 10,000 to 7000 years before present, when the rate of sea level rise was even higher than today as a result of glacial ice melt. Their analysis suggests an upper threshold of 7 millimeters per year as the maximum rate of sea level rise associated with mangrove vertical development, beyond which the ecosystem fails to keep up with the change. Under projected rates of sea level rise, they predict that a deficit between accretion and sea level rise is likely to commence in the next 30 years. Science , this issue p. 1118 ; see also p. 1050

On low-lying, tropical and sub-tropical coastlines freshwater marshes may be replaced by salt‑tolerant mangroves in response to relative sea-level rise. Pollen analysis of radiocarbon‑dated sediment cores showed that such a change occurred in Hungry Bay, Bermuda during the late Holocene. This well-established paleoenvironmental trajectory provides an opportunity to explore if geochemical proxies (bulk-sediment δ13C and Rock-Eval pyrolysis) can reconstruct known environmental changes and relative sea level. We characterized surface sediment from depositional environments in Bermuda (freshwater wetlands, saline mangroves, and wrack composed of Sargassum natans macroalgae) using geochemical measurements and demonstrate that a multi-proxy approach can objectively distinguish among these environments. However, application of these techniques to the transgressive sediment succession beneath Hungry Bay suggests that freshwater peat and mangrove peat cannot be reliably distinguished in the sedimentary record, possibly because of post‑depositional convergence of geochemical characteristics on decadal to multi‑century timescales and/or the relatively small number of modern samples analyzed. Sediment that includes substantial contributions from Sargassum is readily identified by geochemistry, but has a limited spatial extent. Radiocarbon dating indicates that beginning at –700 CE, episodic marine incursions into Hungry Bay (e.g., during storms) carried Sargassum that accumulated as wrack and thickened through repeated depositional events until ~300 CE. It took a further ~550 years for a peat‑forming mangrove community to colonize Hungry Bay, which then accumulated sediment rapidly, but likely out of equilibrium with regional relative sea-level rise. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore) Published version

Relative sea-level (RSL) records from far-field regions distal from ice sheets remain poorly understood, particularly in the early Holocene. Here, we extended the Holocene RSL data from Singapore by producing early Holocene sea-level index points (SLIPs) and limiting dates from a new ~40 m sediment core. We merged new and published RSL data to construct a standardized Singapore RSL database consisting of 88 SLIPs and limiting data. In the early Holocene, RSL rose rapidly from −21.0 to −0.7 m from ~9500 to 7000 cal. yrs. BP. Thereafter, the rate of RSL rise decelerated, reaching a mid-Holocene highstand of 4.0 ± 4.5 m at 5100 cal. yrs. BP, before falling to its present level. There is no evidence of any inflections in RSL when the full uncertainty of SLIPs is considered. When combined with other standardized data from the Malay-Thai Peninsula, our results also show substantial misfits between regional RSL reconstructions and glacial isostatic adjustment (GIA) model predictions in the rate of early Holocene RSL rise, the timing of the mid-Holocene highstand and the nature of late-Holocene RSL fall towards the present. It is presently unknown whether these misfits are caused by regional processes, such as subsidence of the continental shelf, or inaccurate parameters used in the GIA model. Ministry of Education (MOE) Ministry of National Development (MND) Nanyang Technological University National Environmental Agency (NEA) National Research Foundation (NRF) Published version This research was supported by the Earth Observatory of Singapore (EOS) grants M4430132.B50-2014 (Singapore Quaternary Geology), M4430139.B50-2015 (Singapore Holocene Sea Level), M4430188.B50-2016 (Singapore Drilling Project), M4430245. B50-2017 and M4430245.B50-2018 (Kallang Basin Project). SC, ADS, TL, HC, TAS and BPH are supported by the Singapore Ministry of Education Academic Research Fund MOE2019-T3-1-004 and MOE2018-T2-1-030, the National Research Foundation Singapore, the Singapore Ministry of Education under the Research Centers of Excellence initiative, and by the Nanyang Technological University. This research is also supported by the National Research Foundation, Prime Minister’s Office, Singapore and the Ministry of National Development, Singapore under the Urban Solutions & Sustainability – Integration Fund (USS-IF Award No. USS-IF-2020-1). It is part of the National Sea Level Programme under the National Environment Agency.

We present PALEO-SEAL, a simple web interface that allows visualizing, querying and downloading Holocene sea-level datapoints formatted following the HOLSEA data template. The data is hosted on a mySQL database, and the interface uses AngularJS. PALEO-SEAL is scalable to large datasets and can be deployed in few easy steps, that require only basic knowledge of SQL and HTML. The tool is released in the open domain.

Building robust age-depth models to understand climatic and geologic histories from coastal sedimentary archives often requires composite chronologies consisting of multi-proxy age markers. Pollen chronohorizons derived from a known change in vegetation are important for age-depth models, especially those with other sparse or imprecise age markers. However, the accuracy of pollen chronohorizons compared to other age markers and the impact of pollen chronohorizons on the precision of age-depth models, particularly in salt marsh environments, is poorly understood. Here, we combine new and published pollen data from eight coastal wetlands (salt marshes and mangroves) along the Atlantic Coast of the United States (U.S.) from Florida to Connecticut to define the age and uncertainty of 17 pollen chronohorizons. We found that 13 out of 17 pollen chronohorizons were consistent when compared to other age markers (radiocarbon, radionuclide 137Cs and pollution markers). Inconsistencies were likely related to the hyperlocality of pollen chronohorizons, mixing of salt marsh sediment, reworking of pollen from nearby tidal flats, misidentification of pollen signals, and inaccuracies in or misinterpretation of other age markers. Additionally, in a total of 24 models, including one or more pollen chronohorizons, increased precision (up to 41 years) or no change was found in 18 models. Ministry of Education (MOE) National Research Foundation (NRF) Published version MC was funded by the National Science Foundation EAR 1624551. NSK, TS, and BPH were funded by the Ministry of Education Academic Research Fund MOE2018-T2-1-030 and MOE2019-T3-1-004, the National Research Foundation Singapore, and the Singapore Ministry of Education, under the Research Centres of Excellence initiative. This article is a contribution to International Geoscience Program (IGCP) Project 639, “Sea Level Change from Minutes to Millennia”. This work is Earth Observatory of Singapore contribution 349. AP wishes to acknowledge the funding Science Foundation Ireland Career Development Award (17/CDA/4695); an investigator award (16/IA/4520); a Marine Research Programme funded by the Irish Government, co-financed by the European Regional Development Fund (Grant-Aid Agreement No. PBA/CC/18/01); European Union’s Horizon 2020 research and innovation programme under grant agreement No 818144; and SFI Research Centre awards 16/RC/3872 and 12/RC/2289_P2.

Coastal geologic records allow for the assessment of long-term patterns of tropical cyclone variability. However, the accuracy of geologic reconstructions of tropical cyclones is limited by the lack of modern analogues. We describe the microfossil (foraminifera and testate amoebae) assemblages contained within overwash sediments deposited by Typhoon Haiyan when it made landfall on the islands of Leyte and Samar in the Philippines on 7 November 2013 as a Category 5 super typhoon. The overwash sediments were transported up to 1.7 km inland at four study sites. The sediments consisted of light brown medium sand in a layer

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

High-quality relative sea-level (RSL) data reveal spatial and temporal variations in crustal movements during the Holocene, which are used for many applications, ranging from calibrating models of earth rheology and ice sheet reconstructions to the development of coastal lowlands and human occupation. Here, we present a Holocene RSL database for the Atlantic coast of Europe (ACE) and estimate rates of RSL change from the ACE database using a spatio-temporal empirical hierarchical model. The database contains 214 index points, which locate the RSL position in space and time, and 126 limiting dates, which constrain RSL to above or below a certain elevation at a specific point in time. The temporal distribution extends from present to ~11.5 ka, with only 42 index points older than 7 ka. The spatial distribution spans 1700 km from French Flanders (France) to Algarve (Portugal), with more than half of the index points concentrated along the French coast. The ACE database shows RSL was below present during the Holocene. Rates of RSL change were highest during the early Holocene, ranging between 6.8 ± 0.5 mm yr-1 in middle Portugal and 6.3 ± 0.8 mm yr-1 in southern France from 10 to 7 ka. Mid-to late-Holocene rates decreased over time with rates ranging between 0.9 ± 0.4 mm yr-1 in middle France and 0.1 ± 0.5 mm yr-1 in middle Portugal from 4 ka to present. Comparison of the RSL data to output from a glacial-isostatic adjustment model suggests that deglaciation of the British-Irish and Fennoscandian Ice Sheets dominates the large-scale variability captured by the ACE database, which reflects a decreasing influence of the collapsing British-Irish and Fennoscandian peripheral forebulge that migrated from the northeast to the northwest after ~4 ka. (c) 2018 Elsevier Ltd AGA received a postdoctoral grant from the Basque Government ( POS-2014-1-51 ). AC and AGA were supported by Antropicosta (MINECO, CGL2013-41083-P ), Harea-Coastal Geology Research Group ( EJ/GV, IT976-16 ) and Quaternary Unit for Research and Education ( UPV/EHU , UFI11/09 ) grants. REK was supported in part by NSF grants OCE-1458904 and OCE-1702587 . BPH was supported by Singapore Ministry of Education Academic Research Fund Tier 1 RG119/17 , the National Research Foundation Singapore , and the Singapore Ministry of Education, under the Research Centres of Excellence initiative

We present the first quality-controlled relative sea-level (RSL) database for the Russian Arctic coast from the Barents Sea in the west to Laptev Sea in the east (29–152oE and 63 to 81oN). The database consists of 385 sea-level index points and 249 limiting dates and spans 24 ka to present. Sea-level indicators are derived from multiple proxies, including isolation basins, raised beaches, glacial erratics, marine terraces, laidas (salt marshes), and deltaic salt marshes. Here, we calculate the indicative meanings for all indicators and evaluated possible elevation errors. We have estimated the ages and uncertainties of index points and limiting dates using the most recent calibration datasets. In the western Russian Arctic (Barents and White Seas), RSL was driven by glacial isostatic adjustment (GIA) due to deglaciation of the Eurasian ice sheet complex. For example, within the Baltic crystalline shield, RSL fell rapidly from 80 to 100 m at 11–12 ka to 15–25 m at ∼4–5 ka. In the Arctic Islands of Franz-Joseph Land and Novaya Zemlya, RSL gradually fell from 25 to 35 m at 9 ka to 5–10 m at 3 ka. The Timan coast and the Kara Sea shelf are characterized by constant RSL rise due to proglacial forebulge collapse; Yamal and the Gydan Peninsula and Novaya Zemlya are all marked by a high LGM position of RSL, followed by a lowstand and consequent rise to a late Holocene highstand of several meters. Data from the Laptev Sea coasts and shelf and the New Siberian Islands demonstrate post-LGM RSL rise with a Holocene highstand of up to 5–10 m, with scatter caused by differential tectonic movements along a diffuse lithospheric plate boundary. The collected database allowed to estimate and discuss the reasons of both spatial and temporal variability of RSL histories in different parts of the Russian Arctic.

This study presents a synthesis of century-scale hydroclimate variations in North America for the Common Era (last 2000 years) using new age models of previously published multiple proxy-based paleoclimate data. This North American Hydroclimate Synthesis (NAHS) examines regional hydroclimate patterns and related environmental indicators, including vegetation, lake water elevation, stream flow and runoff, cave drip rates, biological productivity, assemblages of living organisms, and salinity. Centennial-scale hydroclimate anomalies are obtained by iteratively sampling the proxy data on each of thousands of age model realizations and determining the fractions of possible time series indicating that the century-smoothed data was anomalously wet or dry relative to the 100 BCE to 1900 CE mean. Results suggest regionally asynchronous wet and dry periods over multidecadal to centennial timescales and frequent periods of extended regional drought. Most sites indicate drying during previously documented multicentennial periods of warmer Northern Hemisphere temperatures, particularly in the western U.S., central U.S., and Canada. Two widespread droughts were documented by the NAHS: from 50 BCE to 450 CE and from 800 to 1100 CE. Major hydroclimate reorganizations occurred out of sync with Northern Hemisphere temperature variations and widespread wet and dry anomalies occurred during both warm and cool periods. We present a broad assessment of paleoclimate relationships that highlights the potential influences of internal variability and external forcing and supports a prominent role for Pacific and Atlantic Ocean dynamics on century-scale continental hydroclimate., final draft, peerReviewed

Characterizing the spatio-temporal variability of relative sea level (RSL) and estimating local, regional, and global RSL trends requires statistical analysis of RSL data. Formal statistical treatments, needed to account for the spatially and temporally sparse distribution of data and for geochronological and elevational uncertainties, have advanced considerably over the last decade. Time-series models have adopted more flexible and physically-informed specifications with more rigorous quantification of uncertainties. Spatio-temporal models have evolved from simple regional averaging to frameworks that more richly represent the correlation structure of RSL across space and time. More complex statistical approaches enable rigorous quantification of spatial and temporal variability, the combination of geographically disparate data, and the separation of the RSL field into various components associated with different driving processes. We review the range of statistical modeling and analysis choices used in the literature, reformulating them for ease of comparison in a common hierarchical statistical framework. The hierarchical framework separates each model into different levels, clearly partitioning measurement and inferential uncertainty from process variability. Placing models in a hierarchical framework enables us to highlight both the similarities and differences among modeling and analysis choices. We illustrate the implications of some modeling and analysis choices currently used in the literature by comparing the results of their application to common datasets within a hierarchical framework. In light of the complex patterns of spatial and temporal variability exhibited by RSL, we recommend non-parametric approaches for modeling temporal and spatio-temporal RSL., Comment: 30 pages, 7 figures

Future sea-level rise generates hazards for coastal populations, economies, infrastructure, and ecosystems around the world. The projection of future sea-level rise relies on an accurate understanding of the mechanisms driving its complex spatio-temporal evolution, which must be founded on an understanding of its history. We review the current methodologies and data sources used to reconstruct the history of sea-level change over geological (Pliocene, Last Interglacial, and Holocene) and instrumental (tide-gauge and satellite alimetry) eras, and the tools used to project the future spatial and temporal evolution of sea level. We summarize the understanding of the future evolution of sea level over the near (through 2050), medium (2100), and long (post-2100) terms. Using case studies from Singapore and New Jersey, we illustrate the ways in which current methodologies and data sources can constrain future projections, and how accurate projections can motivate the development of new sea-level research questions across relevant timescales. Ministry of Education (MOE) National Research Foundation (NRF) The authors acknowledge funding from Singapore Ministry of Education Academic Research Fund Tier 1 RG119/17, the National Research Foundation Singapore, and the Singapore Ministry of Education, under the Research Centres of Excellence initiative; US National Ocean and Atmospheric Administration (NOAA) Grant NA11OAR4310101; US National Science Foundation (NSF) Grants ICER-1663807, OCE 1458904 and 1702587, EAR 1520683, and Postdoctoral Fellowship 1625150; National Aeronautics and Space Administration (NASA) Grant 80NSSC17K0698; the Community Foundation of New Jersey; and David and Arleen McGlade. This article is a contribution to PALSEA2 (Palaeo-Constraints on Sea-Level Rise), International Geoscience Program (IGCP) Project 639, “Sea Level Change from Minutes to Millennia,” and INQUA Project 1601P “Geographic variability of HOLocene relative SEA level (HOLSEA).” This work is Earth Observatory of Singapore contribution no. 198.

We examined the use of d 13 C, TOC and C/N geochemistry of sedimentary organic matter to reconstruct former sea levels and paleoenvironments in the absence of suitable microfossil data. The modern distribution of d 13 C, TOC and C/N of 33 vegetation and 74 surface sediment samples collected from four coastal wetlands in the Thames Estuary and Norfolk, UK are described. The d 13 C, TOC and C/N geochemistry of sediments varied in relation to the input of in situ vascular vegetation versus allochthonous particulate organic matter and algae, which was controlled primarily by tidal inundation. We reviewed published and unpublished studies to produce an English database of vegetation (n ¼257) and sediment (n ¼132) d 13 C, TOC and C/N geochemistry. Four elevation-dependent environments in the database had statistically distinct d 13 C, TOC and C/N values: (1) tidal flat/low marsh (d 13 C: � 24.9 � 1.2‰; TOC: 3.6 � 1.7%; C/N: 9.9 � 0.8); (2) middle marsh/high (d 13 C: � 26.2 � 1.0‰; TOC: 9.8 � 6.7%; C/N: 12.1 � 1.8); (3) reed swamp (d 13 C: � 27.9 � 0.7‰: TOC: 36.5 � 11.5%; C/ N: 13.9 � 1.2); and (4) fen carr (d 13 C: � 29.0 � 0.6‰; TOC: 41.6 � 5.7%; C/N: 17.4 � 3.1). The d 13 C, TOC and C/ N geochemistry database was applied to a Holocene sediment core collected from the Thames Estuary to produce three new sea-level index points and one limiting date, illustrating the utility of d 13 C, TOC and C/N values to reconstruct Holocene relative sea levels. Copyright © 2015 John Wiley & Sons, Ltd.

We investigated the influence of inter-annual and seasonal differences on the distribution of live and dead foraminifera, and the inter-annual variability of stable carbon isotopes (d 13 C), total organic carbon (TOC) values and carbon to nitrogen (C/N) ratios in bulk sediments from intertidal environments of Bandon Marsh (Oregon, USA). Living and dead foraminiferal species from 10 stations were analyzed over two successive years in the summer (dry) and fall (wet) seasons. There were insignificant inter-annual and seasonal variations in the distribution of live and dead species. But there was a noticeable decrease in calcareous assemblages (Haynesina sp.) between live populations and dead assemblages, indicating that most of the calcareous tests were dissolved after burial; the agglutinated assemblages were comparable between constituents. The live populations and dead assemblages were dominated by Miliammina fusca in the tidal flat and low marsh, Jadammina macrescens, Trochammina inflata and M. fusca in the high marsh, and Trochamminita irregularis and Balticammina pseudomacrescens in the highest marsh to upland. Geochemical analyses (d 13 C, TOC and C/N of bulk sedimentary organic matter) show no significant influence of inter-annual variations but a significant correlation of d 13 C values (R = 20.820, p , 0.001), TOC values (R = 0.849, p , 0.001) and C/N ratios (R = 0.885, p , 0.001) to elevation with respect to the tidal frame. Our results suggest that foraminiferal assemblages and d 13 C and TOC values, as well as C/N ratios, in Bandon

Sea-level and ice-sheet databases have driven numerous advances in understanding the Earth system. We describe the challenges and offer best strategies that can be adopted to build self-consistent and standardised databases of geological and geochemical information used to archive palaeo-sea-levels and palaeo-ice-sheets. There are three phases in the development of a database: (i) measurement, (ii) interpretation, and (iii) database creation. Measurement should include the objective description of the position and age of a sample, description of associated geological features, and quantification of uncertainties. Interpretation of the sample may have a subjective component, but it should always include uncertainties and alternative or contrasting interpretations, with any exclusion of existing interpretations requiring a full justification. During the creation of a database, an approach based on accessibility, transparency, trust, availability, continuity, completeness, and communication of content (ATTAC3) must be adopted. It is essential to consider the community that creates and benefits from a database. We conclude that funding agencies should not only consider the creation of original data in specific research-question-oriented projects, but also include the possibility of using part of the funding for IT-related and database creation tasks, which are essential to guarantee accessibility and maintenance of the collected data.

Stable carbon isotopes (δ13C) and the ratio of organic carbon to total nitrogen (C/N) are able to differentiate sources of organic matter that accumulate in coastal depositional sequences, which makes them useful to reconstruct former sea levels. This chapter describes the factors that influence δ13C and C/N geochemistry of coastal wetland sediments, outlines basic methods for its use in relative sea-level reconstruction, and draws attention to several case studies.

Holocene relative sea-level (RSL) records exhibit spatial and temporal variability that arises mainly from the interaction of eustatic (land ice volume and thermal expansion) and isostatic (glacio- and hydro-) factors. We fit RSL histories from near-, intermediate-, and far-field locations with noisy-input Gaussian process models to assess rates of RSL change. Records from near-field regions (e.g., Antarctica, Greenland, Canada, Sweden, and Scotland) reveal a complex pattern of RSL fall from a maximum marine limit due to the net effect of eustatic sea-level rise and glacio-isostatic uplift with rates of RSL fall as great as -69 �� 9 m/ka. Intermediate-field regions (e.g., mid-Atlantic and Pacific coasts of the United States, Netherlands, Southern France, St. Croix) display variable rates of RSL rise from the cumulative effect of isostatic and eustatic factors. Fast rates of RSL rise (up to 10 �� 1 m/ka) are found in the early Holocene in regions near the center of forebulge collapse. Far-field RSL records exhibit a mid-Holocene highstand, the timing (between 8 and 4 ka) and magnitude (between

Management and restoration of the Mississippi River deltaic plain (southern United States) and associated wetlands require a quantitative understanding of sediment delivery during large flood events, past and present. Here, we investigate the sedimentary fingerprint of the 2011 Mississippi River flood across the Louisiana coast (Atchafalaya Delta, Terrebonne, Barataria, and Mississippi River Delta basins) to assess spatial patterns of sedimentation and to identify key indicators of sediment provenance. The sediment deposited in wetlands during the 2011 flood was distinguished from earlier deposits based on biological characteristics, primarily absence of plant roots and increased presence of centric (planktonic) diatoms indicative of riverine origin. By comparison, the lithological (bulk density, organic matter content, and grain size) and chemical (stable carbon isotopes of bulk organic matter) properties of flood sediments were nearly identical to the underlying deposit. Flood sediment deposition was greatest in wetlands near the Atchafalaya and Mississippi Rivers and accounted for a substantial portion (37% to 85%) of the annual accretion measured at nearby monitoring stations. The amount of sediment delivered to those basins (1.1–1.6 g cm−2) was comparable to that reported previously for hurricane sedimentation along the Louisiana coast (0.8–2.1 g cm−2). Our findings not only provide insight into how large-scale river floods influence wetland sedimentation, they lay the groundwork for identifying previous flood events in the stratigraphic record.