Increasing Sea Level Rise Research Articles

Coupled ice–ocean interactions during future retreat of West Antarctic ice streams in the Amundsen Sea sector

Abstract. The Amundsen Sea sector has some of the fastest-thinning ice shelves in Antarctica, caused by high, ocean-driven basal melt rates, which can lead to increased ice streamflow, causing increased sea level rise (SLR) contributions. In this study, we present the results of a new synchronously coupled ice-sheet–ocean model of the Amundsen Sea sector. We use the Wavelet-based, Adaptive-grid, Vertically Integrated ice sheet model (WAVI) to solve for ice velocities and the Massachusetts Institute of Technology general circulation model (MITgcm) to solve for ice thickness and three-dimensional ocean properties, allowing for full mass conservation in the coupled ice–ocean system. The coupled model is initialised in the present day and run forward under idealised warm and cold ocean conditions with a fixed ice front. We find that Thwaites Glacier dominates the future SLR from the Amundsen Sea sector, with a SLR that evolves approximately quadratically over time. The future evolution of Thwaites Glacier depends on the lifespan of small pinning points that form during the retreat. The rate of melting around these pinning points provides the link between future ocean conditions and the SLR from this sector and will be difficult to capture without a coupled ice–ocean model. Grounding-line retreat leads to a progressively larger Thwaites Ice Shelf cavity, leading to a positive trend in total melting, resulting from the increased ice basal surface area. Despite these important sensitivities, Thwaites Glacier retreats even in a scenario with zero ocean-driven melting. This demonstrates that a tipping point may have been passed in these simulations and some SLR from this sector is now committed.

Intrinsically Episodic Antarctic Shelf Intrusions of Circumpolar Deep Water via Canyons

Abstract The structure of the Antarctic Slope Current at the continental shelf is crucial in governing the poleward transport of warm water. Canyons on the continental slope may provide a pathway for warm water to cross the slope current and intrude onto the continental shelf underneath ice shelves, which can increase rates of ice shelf melting, leading to reduced buttressing of ice shelves, accelerating glacial flow and hence increased sea level rise. Observations and modeling studies of the Antarctic Slope Current and cross-shelf warm water intrusions are limited, particularly in the East Antarctica region. To explore this topic, an idealized configuration of the Antarctic Slope Current is developed, using an eddy-resolving isopycnal model that emulates the dynamics and topography of the East Antarctic sector. Warm water intrusions via canyons are found to occur in discrete episodes of large onshore flow induced by eddies, even in the absence of any temporal variability in external forcings, demonstrating the intrinsic nature of these intrusions to the slope current system. Canyon width is found to play a key role in modulating cross-shelf exchanges; warm water transport through narrower canyons is more irregular than transport through wider canyons. The intrinsically episodic cross-shelf transport is found to be driven by feedbacks between wind energy input and eddy generation in the Antarctic Slope Current. Improved understanding of the intrinsic variability of warm water intrusions can help guide future observational and modeling studies in the analysis of eddy impacts on Antarctic shelf circulation.

A mud budget of the Wadden Sea and its implications for sediment management

The world’s coasts and deltas are progressively threatened by climate change and human activities. The degree at which coastlines can adapt to these changes strongly depends on the sediment availability. The availability of muddy sediments is however poorly known. This study aims at developing a mud budget for the world’s largest system of uninterrupted tidal flats: the Wadden Sea. The resulting mud budget is nearly closed: ~ 12 million ton/year enters the system on its western end, ~ 1.5 million ton/year is added by local rivers, while ~ 12 million ton annually deposits or is extracted by anthropogenic activities. A mud deficit already exists in the downdrift areas, which will only become more pronounced with increased sea level rise rates. Mud is thus a finite resource similar to sand, and should be treated as such in sediment management strategies. Resolving future challenges will therefore require a cross-border perspective on sediment management.

The missing link in New Jersey’s Hurricane Sandy recovery: Land use management

Hurricane Sandy devastated New Jersey with record storm surge, coastal erosion and inundation, widespread flooding, and associated property damage. The federal response to this catastrophic storm event was swift, with passage of a supplemental appropriation bill in excess of $60 billion to facilitate response and recovery. In New Jersey, hurricane recovery included a range of positive mitigation actions, including structural elevation of residential and smaller commercial buildings, property acquisitions, restoration of natural resources, enhanced construction standards, and large-scale beach nourishment. However, New Jersey’s recovery plan promoted quick rebuilding without consideration of long-term storm vulnerability concerns, and without fully understanding the cause of damages and appropriate land use management actions that could mitigate future storm and flood damages. There was a conspicuous absence of land use planning and management strategies in the context of future conditions of increasing sea level rise, chronic coastal erosion and increasing risk to people and property. This deficiency represents a significant gap in New Jersey’s Hurricane Sandy recovery and a missed opportunity to address a long-standing vulnerability.

TRANSFORMING DEVELOPMENT MODELS TO ADAPT TO CLIMATE CHANGE IN VIETNAM TODAY

In the context of climate change and increasing sea level rise, unpredictably affecting the survival of humanity, there is a danger of erasing the economic development achievements of countries. In response to climate change and sea level rise, countries have transformed their growth model to green growth - considering this an inevitable development trend, both a means and a result of sustainable development and environmental protection. Vietnam is not an exception to that general trend. The article clarifies a number of contents related to climate change, overviews climate change in Vietnam in the past time and scenarios to cope with climate change to clarify the transition to green growth in accordance with the circumstances of Vietnam, thereby making some recommendations to better implement green growth in Vietnam in the coming time.<p> </p><p><strong> Article visualizations:</strong></p><p><img src="/-counters-/soc/0099/a.php" alt="Hit counter" /></p>

A global assessment of estuarine tidal response to sea level rise

Climate change induced sea level rise (SLR) is one of the greatest challenges threatening the sustainable management of estuaries worldwide. Current knowledge regarding SLR and estuarine hydrodynamics is primarily focused on individual case studies, which provides limited guidance on how different estuary typologies will respond to SLR. To expand the current knowledge, this research used an idealised hydrodynamic approach to analyse the tidal range dynamics of 25 real-world estuaries with diverse shapes and boundary conditions, providing insights into estuarine response to SLR-induced tidal variations. Under present-day conditions, short length estuaries with wide entrances, deep waters, strong convergence, macro-tidal conditions, low values of roughness, and low upland river inflows are likely to experience amplified tidal range patterns; whereas lengthy estuaries with narrow entrances, shallow water depths, micro/meso-tidal conditions, high values of roughness, and high upland river inflows often exhibit a mix of dampened-amplified or fully dampened tidal range patterns. Under the effects of SLR, estuarine tidal range dynamics change depending on their present-day tidal range patterns. Where the present-day tidal range pattern is either dampening, a mix of dampening/amplification, or amplification, SLR increases (up to 61 %), moderately increases (up to 26 %), and slightly decreases/increases (up to 5 %) the tidal range of estuaries, respectively. Considering the relationship between an estuary's present-day tidal range pattern and its response to SLR, the presented approach may be useful in providing an initial assessment of SLR effects in estuaries worldwide. This approach may also help to identify sites most impacted by future SLR, and to direct decision-making towards evidence-based management approaches.

Climate-driven tradeoffs between landscape connectivity and the maintenance of the coastal carbon sink

Ecosystem connectivity tends to increase the resilience and function of ecosystems responding to stressors. Coastal ecosystems sequester disproportionately large amounts of carbon, but rapid exchange of water, nutrients, and sediment makes them vulnerable to sea level rise and coastal erosion. Individual components of the coastal landscape (i.e., marsh, forest, bay) have contrasting responses to sea level rise, making it difficult to forecast the response of the integrated coastal carbon sink. Here we couple a spatially-explicit geomorphic model with a point-based carbon accumulation model, and show that landscape connectivity, in-situ carbon accumulation rates, and the size of the landscape-scale coastal carbon stock all peak at intermediate sea level rise rates despite divergent responses of individual components. Progressive loss of forest biomass under increasing sea level rise leads to a shift from a system dominated by forest biomass carbon towards one dominated by marsh soil carbon that is maintained by substantial recycling of organic carbon between marshes and bays. These results suggest that climate change strengthens connectivity between adjacent coastal ecosystems, but with tradeoffs that include a shift towards more labile carbon, smaller marsh and forest extents, and the accumulation of carbon in portions of the landscape more vulnerable to sea level rise and erosion.

Impact assessment of climate change on compound flooding in a coastal city

Flood disasters in coastal cities are generally caused by the combined effect of typhoon rainfall, storm surge and other factors. Coastal cities will face more severe compound flooding under climate change. Although some studies have analyzed compound flooding under climate change, there is a lack of research considering the combined effect of sea level rise (SLR) and future rainfall changes, especially lack of the jacking effect of SLR on the volume and duration of compound flooding. This paper investigates the impact of future rainfall changes and SLR on compound flood risk, via a case study of a coastal city, Haikou, China. Future rainfall in Haikou is obtained by bias correction of rainfall from five global climate models (GCMs) in CMIP5. The SLR in 2050 and 2090 is predicted according to IPCC. Then, a 1D/2D hydrological-hydrodynamic model for dynamic simulation of surface runoff is applied to simulate compound flooding. Results show that both future rainfall changes and SLR will lead to the increase of flood extent, flood depth and flood duration. But future rainfall changes will have a greater impact on flood, and the combined effect of future rainfall changes and SLR on flood is greater than the sum of their individual effects. The individual effects of SLR and future rainfall changes would increase flood depth in 10.6 % and 32.1 % of the study area, respectively, while their combined effect would increase this proportion to 34.9 %. Also, the jacking effect of SLR on compound flooding will lead to an increase in flood volume, but it presents a nonlinear relationship that gradually slows down with the increase of SLR. A SLR of 0.3 m and 0.63 m will lead to a 2.34 % and 3.22 % increase in flood volume, respectively. And the jacking effect of SLR is more obvious when future rainfall changes are considered, which will lead to a sharp increase in the duration of compound flooding. Moreover, water storage facilities and tidal gates are effective ways to reduce the impact of climate change on compound flooding.

Sea level rise may pose conservation challenges for the endangered Cape Sable seaside sparrow

Biodiversity conservation under a changing climate is a challenging endeavor. Landscapes are shifting as a result of climate change and sea level rise but plant communities in particular may not keep up with the pace of change. Predictive ecological models can help decision makers understand how species are likely to respond to change and then adjust management actions to align with desired future conditions. Florida’s Everglades is a wetland ecosystem that is host to many species, including a large number of endangered and endemic species. Everglades ecosystem restoration has been ongoing for decades, but consideration of sea level rise impacts in restoration planning is more recent. Incorporating potential impacts from sea level rise into restoration planning should benefit species and their coastal habitats, most notably at the southern Florida peninsula. The endangered Cape Sable seaside sparrow (Ammospiza maritima mirabilis) occurs in marl prairie habitat at the southern end of the Everglades. The locations of three of its six subpopulations are proximate to the coast. We used a spatially explicit predictive model, EverSparrow, to estimate probability of sparrow presence considering both hydrologic change from restoration and sea level rise. We found that the probability of sparrow presence decreased with increasing sea level rise. Within approximately 50 years, probability of presence significantly decreased for all three coastal subpopulation areas, with areas above 40% probability increasingly limited. Given the exceptionally low dispersal ability of this species and the geographic restrictions for habitat expansion, our results highlight the importance of freshwater flow into the southern Everglades marl prairie for habitat conservation.

Assessing the effects of sediment and tidal level variability on coastal wetland evolution

• We include short-term sediment and tidal variability on coastal wetland evolution. • We first simulate 10-year evolution of a mangrove-saltmarsh wetland using field data. • Stormy years promote saltmarsh transgression, but accretion is barely affected. • MC method and synthetic data are used next to assess uncertainty over the century. • Results excluding variability underestimate wetland extent/accretion by up to 25% Assessments of coastal wetland vulnerability to Sea Level Rise (SLR) frequently use simplified representations of tidal levels and sediment input (i.e., average or representative values), disregarding short and long-term variations. The expensive computational cost of using high-resolution time series is one of the main reasons for such simplification. However, observed series contain short-term variations (such as severe storms) and interannual variability induced by climate and ocean phenomena. In this study, we used a previously developed ecogeomorphological model and high-performance computing to carry out simulations with observed and synthetic high-resolution datasets to account for both types of variations. We performed two experiments. In the first experiment we used observed water levels and satellite-derived sediment concentrations from 2002 to 2011 to assess the capability of the model to reproduce in situ measurements of soil elevation change in a mangrove-saltmarsh wetland in SE Australia. Results showed increased wetland extent (particularly in saltmarsh) and soil elevation change in years with important storms, but little effect on the long term trends of soil elevation and wetland evolution. In the second experiment, we implemented a Monte Carlo (MC) approach comprising 100 realizations of 100-year duration using synthetically-generated input data based on 13 years of high-resolution values of water levels and sediment load. Each simulation covered the period between 2000 and 2100 and included increases in SLR following the RCP 8.5 scenario. The MC results show that the variability of inputs generate uncertainties in wetland evolution, with up to 20% of wetland area extent classified as highly uncertain during the second half of the century. In agreement with the first experiment, uncertainty was higher in saltmarsh. In addition, uncertainty in elevation change was lower than in wetland extent. MC results were compared with simulations using representative sinusoidal waves and constant sediment concentration, one using the mean tidal range and the other using a combination of neap, mean and spring tidal ranges. Both simplified formulations underestimated wetland extent (particularly in saltmarsh), but the simulations with the combination of tidal ranges were able to match the soil elevation change results from the MC approach.

Elevation change of the Antarctic Ice Sheet: 1985 to 2020

Abstract. The largest uncertainty in future projections of sea level change comes from the uncertain response of the Antarctic Ice Sheet to the warming oceans and atmosphere. The ice sheet gains roughly 2000 km3 of ice from precipitation each year and loses a similar amount through solid ice discharge into the surrounding oceans. Numerous studies have shown that the ice sheet is currently out of long-term equilibrium, losing mass at an accelerated rate and increasing sea level rise. Projections of sea level change rely on accurate estimates of the contribution of land ice to the contemporary sea level budget. The longest observational record available to study the mass balance of the Earth's ice sheets comes from satellite altimeters. This record, however, consists of multiple satellite missions with different life spans and inconsistent measurement types (radar and laser) of varying quality. To fully utilize these data, measurements from different missions must be cross-calibrated and integrated into a consistent record of change. Here, we present a novel approach for generating such a record that implies improved topography removal, cross-calibration, and normalization of seasonal amplitudes from different mission. We describe in detail the advanced geophysical corrections applied and the processes needed to derive elevation change estimates. We processed the full archive record of satellite altimetry data, providing a seamless record of elevation change for the Antarctic Ice Sheet that spans the period 1985 to 2020. The data are produced and distributed as part of the NASA MEaSUREs ITS_LIVE (Making Earth System Data Records for Use in Research Environments Inter-mission Time Series of Land Ice Velocity and Elevation) project (Nilsson et al., 2021, DOI: https://doi.org/10.5067/L3LSVDZS15ZV​​​​​​​).

Dynamics and Causes of Sea Level Rise in the Coastal Region of Southwest Bangladesh at Global, Regional, and Local Levels

Global greenhouse gas emissions have caused sea level rise (SLR) at a global and local level since the industrial revolution, mainly through thermal expansion and ice melting. Projections indicate that the acceleration of SLR will increase in the near future. This will affect coastal and deltaic populations worldwide, such as in Bangladesh, where almost half of the population resides in regions lower than 5 m above sea level. This study found three coastal tidal gauges and five deltaic gauge stations, which showed increases in SLR at greater rates than the regional and global averages. This research also used satellite altimetry data to analyze regional and global SLR averages in the recent past and the 21st century. There is a trend towards increasing sea level based on results from three tide gauge stations: Char Changa with 7.6 mm/yr, Hiron Point at 3.1 mm/yr from 1993 to 2019, and 14.5 mm/yr at Cox’s Bazar from 1993 to 2011. Based on the linear trend from these time frames, it is projected that SLR in Char Changa will increase by 228 mm from 2020 to 2050, and by 608 mm by 2100, at Hiron Point by 93 mm in 2050 and 248 mm by 2100, and at Cox’s Bazar by almost 435.7 mm by 2050, and more than 1162 mm by 2100. Based on an average from satellite altimeters, assuming a linear increase in SLR, the Bay of Bengal shows an increase of 0.4 mm compared to the global trend. Other river delta stations in the study area also show increasing SLR, specifically, at Kalaroa, Benarpota, Kaikhali, Tala Magura, and Elarchari. Kalaroa and Benarpota show the highest, with SLR of >40 mm/yr. It is also observed that increasing SLR trends are far higher than coastal tide gauges, indicating that physical processes in the delta region are affecting SLR, further contributing to either an increase in water volume/SLR or activating land subsidence. This is partly due to the subsidence of the delta as a result of natural and anthropomorphic effects, as well as an increase in Himalayan glacier melting due to global warming. This indicates that Bangladesh coastal areas will soon experience a far greater SLR than the rest of the Bay of Bengal or other global coastal areas.

Beach nourishment provides resilient protection for critical coastal infrastructure

Hurricanes this century have produced almost a trillion dollars in damages in the U.S., often to critical infrastructure that requires large costs and unacceptable times to repair or replace. There is a need for resilient protection of critical infrastructure where the protection must have the “ability to anticipate, absorb, adapt to, and/or rapidly recover from a potentially disruptive event” and be cost-effective. Coastal infrastructure can be protected by moving infrastructure back from the ocean (retreat), building protective structures, or by beach nourishment to effectively move the ocean back from the infrastructure. Retreat is very costly and highly unpopular on developed shores. Structures are expensive and lack resilience because their failure is usually catastrophic and repair slow. Beach nourishment is the favored protection option on developed shorelines because it significantly reduces infrastructure damage, provides resilient protection, and is cost effective with a high return on investment. The aftermath of Hurricane Sandy provided an example of the tremendous reduction of infrastructure damage due to beach nourishment. Dr. Stewart Farrell, director of the Coastal Research Center in New Jersey, reported: “It really, really works. Where there was a federal beach fill in place, there was no major damage — no homes destroyed. Where there was no beach nourishment, the destruction was complete. Older homes were ripped from foundations and tossed about.” A post-Sandy analysis showed that Corps of Engineers’ beach nourishment projects saved an estimated $1.3 billion in avoided damages. Beach nourishment provides resilient protection. It is partially self-healing, because during a storm some of the sand moves to offshore bars where it causes waves to break and reduces infrastructure damage, and then much of it returns to shore after the storm passes. It can be repaired relatively rapidly by use of a mobile dredge to replace net sand loss. It is a highly adaptable approach to climate change because its rate of sand placement can be varied to raise profiles to offset increased sea level rise. Beach nourishment pays for itself as nice, wide beaches sit in readiness to protect critical coastal infrastructure from storms, while in the meantime, tourists typically generate more than $100 in taxes annually to local, state, and the federal governments for every $1 these governments invest in beach nourishment.

Holocene and historic rates of rock coast erosion – A discussion focussed on Southeast England

Cliff erosion is of concern along inhabited coastlines especially under a scenario of increasing sea level rise. Extrapolation of past erosion rates are often used as a first approximation of future rates, which are or form part of the input into numerical models. However, cliff erosion rates in the Holocene are poorly understood. This is due to the generally short record based on historical maps, which can mask or accentuate erosion rates based on different event frequencies, and, for the more recent cosmogenic exposure dating method, it reflects the large number of variables influencing the concentration of cosmogenic nuclides in rocks at the surface of intertidal shore platforms. The study uses historic maps that go back 400 years, updated (to 2020) recent erosion rates, evidence from mid-Holocene terrestrial habitats in front of present-day cliffs, and a geomorphological landscape type interpretation to provide a better understanding of cliff evolution and erosion history for the cliffs in East Sussex (Southeast England). The paper demonstrates that cliff erosion can only have started in the last few centuries with remnants of Eemian cliffs still present in places. This is supported by published 10Be data. The coastline investigated also shows a persistent decrease in erosion rates to less than half the maximum rate observed in the late 19th to early 20th century despite sea level rise. As a consequence, it appears imperative to understand the local drivers of coastal cliff erosion to assess the future consequences of climate change rather than applying general concepts for example in relation to erosion changes with increasing sea level rise.

Housing Based on Communal Connectivity to Enhance Resilience in Response to Rob Flood

Rob flood is one of flood types caused by the increasing sea level rise submerging in area with lower level than the sea surface. With the hazard occurring regularly, this will be able to threaten the community’s vulnerability in responding to rob flood which includes social, economic, and physical impacts. With the existing housing precedents that lacks in providing a multifaceted aspect between users and its built environment, this paper aims to offer design concept based on communal connectivity to increase the resilience of community in responding rob flood. Communal connectivity focuses on the concept where communities are able to adapt and mitigate either pre-disaster, during disaster, and post-disaster. The study takes place in Semarang at Jl. Ngilir Timur that regularly has rob flood each year with 2050 as the time context. The typology offered in this design is a co-housing settlement with community resilience approach, where this approach focuses on ways to increase the communities‘adaptive capacity. Using force base framework, the main concept offered is a settlement with communal connectivity concept which focuses on several aspects in formal, spatial, material, construction, landscape, and utility. The main concept of this design mainly discusses on social connectivity and supported co-housing in formal and technical explorations which will be able to enhance community resilience in social, economy, and environment aspects.

Importance of Protection Service Against Erosion and Storm Events Provided by Coastal Ecosystems Under Climate Change Scenarios

Increasing sea level rise (SLR), and frequency and intensity of storms, paired with degrading ecosystems, are exposing coastal areas to higher risks of damage by storm events. Coastal natural habitats, such as dunes or saltmarshes, can reduce exposure of coastlines to these events and help to reduce the impacts and the potential damage to coastal property. The goal of our study was to evaluate the current vulnerability of the Portuguese northern coast to erosion and flooding caused by extreme events and to assess the contribution of natural habitats in reducing both vulnerability and property damages considering SLR scenarios. The Integrated Valuation of Environmental Services and Trade-offs (InVEST) Coastal Vulnerability model was used to produce an Exposure Index (EI) for the northern Portuguese coastline, for the current situation, and for future International Panel for Climate Change (IPCC) scenarios Representative Concentration Pathway (RCP) 2.6, RCP4.5, and RCP8.5, considering the presence and absence of coastal habitats. Results showed an increase in exposure with rising sea levels and expansion of high vulnerability areas. Coastal habitats contributed to a 28% reduction of high exposed segments for the Current scenario, corresponding to a potential reduction of coastal property damage of 105 M€ during extreme events. For the SLR scenarios, coastal habitats could potentially reduce the amount of property damage by 190 M€ in 2050 and 285 M€ in 2100, considering RCP8.5 projections. This study highlighted the importance of natural habitats in protecting vulnerable coastlines and reducing the potential damages to properties from flooding. Such results can be incorporated in management plans and support decision-making toward implementing an ecosystem-based approach to increase the resilience of coastal communities to cope with future environmental changes.

Extended Water Level Trends at Long‐Record Tide Gauges Via Moving Window Averaging and Implications for Future Coastal Flooding

AbstractQuantifying the nature and patterns of sea level rise (SLR) is a critical challenge for the sustainability and resilience of coastal zones. Studies of SLR typically consider time‐averaged mean sea level (MSL) trends, however, coastal flooding is more sensitive to extended water level (EWL), which includes time‐variable components such as tides and seasonal variability. Here, we describe a new way to determine long‐term trends of peak extended water levels (PEWL) considering combined monthly averaged MSL and tidal range and their changes in linear rates and variability, which are compared to trends in mean extended water levels (MEWL) over moving 20‐year time windows at long‐period tide gauges over two epochs: century‐scale, and half‐century‐scale. Results show that a majority of locations exhibit different PEWL trends than MEWL trends in both epochs, and this difference has intensified in the past 50 years. There are strong regional coherencies observed: positive PEWL trends along western boundaries of basins (US Atlantic Coast, Japan, and Australia), and negative PEWL trends in most of Europe and the US Pacific Coast. Strong correlations to the Atlantic Multidecadal Oscillation and the Pacific Decadal Oscillation are also observed at many locations. Significant contributions from changes in tidal range and/or variability highlights the importance of considering multiple components of the water level spectrum beyond MSL. Our results are further analyzed in the context of IPCC projections to demonstrate that increased rates of PEWL may have additional implications for future flood levels at locations which have large projected increases in SLR.

Projecting Relative Sea Level Rise under Climate Change at the Phrachula Chomklao Fort Tide Gauge in the Upper Gulf of Thailand

This study aims to project future sea-level rise (SLR) at the Phrachula Chomklao Fort (PCF) tide gauge station in the Upper Gulf of Thailand (UGoT) using the outputs of 35 climate models under two greenhouse gas concentration scenarios: representative concentration pathway 4.5 (RCP4.5) and RCP8.5. The Linear Scaling method was found to be better than Variance Scaling and Quantile Mapping methods for removing biases in raw Global Circulation Models (GCMs) sea level data. Land subsidence, induced by excessive groundwater abstraction, was found to contribute significantly to SLR during the observed period the PCF gauging station; hence, the effects of land subsidence had to be removed from relative sea level before bias correction. The overall increase in SLR is projected to be 0.94–1.05 mm/year under RCP4.5 and 1.07–1.18 mm/year under RCP8.5 for the twenty-first century in the UGoT. The results suggest that future SLR due to climate change will not be as severe in the study region compared to average global projections. However, land subsidence can amplify future SLR. It is therefore important to regulate groundwater abstraction in the future so that SLR can be restricted. It is even more relevant in the UGoT as the raw water intake from the Chao Phraya River for municipal water supply to Bangkok is close to the estuary, and SLR in the future can pose additional challenges for the water utility.

Hydroperiod and Salinity Interactions Control Mangrove Root Dynamics in a Karstic Oceanic Island in the Caribbean Sea (San Andres, Colombia)

Mangroves sustain high soil accretion and carbon sequestration rates, yet it is still unknown if they can keep pace with increasing sea level rise (SLR) across a wider range of coastal geomorphic settings. Because accretion rates are controlled by mineral sediment inputs and organic matter accumulation, it is paramount to assess the relative contribution of root productivity to soil formation. Here, we evaluated root biomass, production, and turnover in three mangrove ecotypes to evaluate the role of soil nutrient limitation, stressors, and hydroperiod in controlling root dynamics in San Andres Island (SAI), a karstic oceanic island in the Caribbean Sea. Root production was modulated by soil stress conditions and not by nutrient availability as it has been reported for other karstic environments. The lowest root biomass allocation, and both production and turnover of fine roots were measured under low flooding duration, and low salinity (<20 PSU) and sulfide concentrations (0.84 ± 0.4 mM). Yet, when soil stress conditions increased during high flooding duration (6207 h y–1) and low oxygen conditions (Eh), root tissues reached the highest biomass and production values, including a relative fast turnover of fine roots (<2 mm; 0.75 y–1). Our results follow the predictions of the plant root longevity cost-benefit hypothesis where plants maintain roots only until the efficiency of resource acquisition is maximized by water and nutrient acquisition. Because of the importance of groundwater in controlling porewater salinity and mangrove root productivity in karstic oceanic islands such as SAI, water use and coastal development should be regulated in the short term to avoid the loss of mangrove area and concomitant ecosystem services.

Predicting the impacts of sea level rise in sea turtle nesting habitat on Bioko Island, Equatorial Guinea.

Sea level is expected to rise 44 to 74 cm by the year 2100, which may have critical, previously un-investigated implications for sea turtle nesting habitat on Bioko Island, Equatorial Guinea. This study investigates how nesting habitat will likely be lost and altered with various increases in sea level, using global sea level rise (SLR) predictions from the Intergovernmental Panel on Climate Change. Beach profiling datasets from Bioko’s five southern nesting beaches were used in GIS to create models to estimate habitat loss with predicted increases in sea level by years 2046–2065 and 2081–2100. The models indicate that an average of 62% of Bioko’s current nesting habitat could be lost by 2046–2065 and 87% by the years 2081–2100. Our results show that different study beaches showed different levels of vulnerability to increases in SLR. In addition, on two beaches erosion and tall vegetation berms have been documented, causing green turtles to nest uncharacteristically in front of the vegetation line. We also report that development plans are currently underway on the beach least susceptible to future increases in sea level, highlighting how anthropogenic encroachment combined with SLR can be particularly detrimental to nesting turtle populations. Identified habitat sensitivities to SLR will be used to inform the government of Equatorial Guinea to consider the vulnerability of their resident turtle populations and projected climate change implications when planning for future development. To our knowledge this is the first study to predict the impacts of SLR on a sea turtle nesting habitat in Africa.