Water balance of the Black Sea catchment area is studied and volumetric analysis of the Black Sea basin is performed in order to estimate sealevel fluctuations during the Last glacial cy- cle. In order to reconstruct the most plausible scenario of the Black Sea reconnection with the Mediterranean, we integrated various data sets available in the literature. These data sets include meteorological re-analysis (ERA-40), as well as more reliable hydro-meteorological observations for the present-day conditions. The latter makes possible to correct the re-analysis data. Hydrological forcing for the past is compiled from various sources including pollen re- constructions and δ 18 O oscillations. Eurasian ice sheet extension is inferred from geological observations and modelling reconstruction available in literature. The latter also has a tem- poral resolution suitable to calculate the corresponding glacial melt water flux at the times of deglaciation. It turns out that about 500 km 3 · y −1 increase of river discharge into the Caspian Sea is needed in order to enable a transport trough the Manych Pass to the Black Sea. Further- more, the mechanisms influencing the variability of the global hydrological cycle due to the glacio-eustaticsealevel change are investigated with the Earth System Model of Intermediate Complexity (EMIC). It is shown that the redistribution of sea - land can have a significant im- pact on the regional climate. In particular, in the Mediterranean area, cooling due to mountain uplift would cause the hydrologic cycle to shift towards drier conditions, while warming due to a changed sea-land distribution would cause a shift towards wet conditions. This result and the above mentioned data are combined to perform an extensive sensitivity study of the Black Sealevel response to the changes of the hydrological cycle components. It is shown that according to the geological reconstruction of the climate the Black Sea water balance remained positive during the Holocene and the catastrophic flood (the Mediterranean waterfall) is not likely to have happened. However, precipitation and evaporation above the sea remain uncertain at that time. Therefore, we have estimated that the increase of maritime evaporation and decrease of maritime precipitation has to be 1.7 times the present-day values in order to achieve a sea-level drop of 140 m which is hypothesized in the flood theory. These results together with geological observations of the last Quaternary glaciation such as oxygen isotopes ratio ( δ 18 O, maritime and ice core record) oscillations and Eurasian ice-sheet extension as an indicator of hydrologi- cal regime change are used to provide theoretical portrayals of likely configurations of the Black
This study focuses on the trigger mechanisms of gravity-driven sediment transport in two submarine canyons at the passive continental margin off NW-Africa during the past 240 kyr. The sedimentary records allow to determine the turbidite emplacement times based on high resolution age models. The sediment textures of the turbidites were studied by using X-ray radiographies. The sedimentary properties like the terrigenous silt size distribution and XRF- core scanning element data allow to identify the variability of the aeolian dust input in the hemipelagic sediments. These variations can be used to reconstruct the climatic conditions in the hinterland which strongly influence the sediment supply on the shelf. In addition a clay mineral assemblage was used to reconstruct the fluvial input of the West-African rivers. The trigger mechanisms of gravity-driven sediment transport in submarine canyons during sealevel changes has been reported from many regions. However, the relationship of sealevel changes and short-term climatic events with turbidite deposition is poorly documented. The turbidite history of the Dakar Canyon during the late Quaternary was reconstructed using gravity cores directly recovered from the canyon axis. The highest frequency of turbidite deposition is restricted to the last two major climatic terminations when remobilisation of sediments from the shelf was triggered by eustaticsealevel rise. Coarse terrigenous silt size data and high Ti/Ca ratios reflect an overall increased dust supply during the last two peak glacials resulting in the formation of extensive sand seas covering the exposed shelf. The interglacials were characterised by less intensive wind stress. However, sporadic turbidite events coincide with the timing of Heinrich events in the North Atlantic. During these times continental climate has changed rapidly towards increased aridity and enhanced wind strength. This in turn led to a higher dust supply which has fed turbidity currents.
During the last decade, several studies investigated the mass loss of the Greenland and West Antarctic Ice Sheet. The melt water ﬂows into the ocean and increases the eustaticsealevel by about 0.3 mm/yr if 100 Gt/yr of mass is lost. To investigate the oceanic response to the additional melt water, diﬀerent amounts of fresh water have been added as additional volume ﬂux along the coast of Greenland. Results are compared to a reference model simulation and conﬁrm the magnitude of global mean sealevel rise, estimated by other studies. The additional volume is distributed over the ocean within days, as barotropic waves are generated. In these perturbation experiments global sealevel rises due to the additional water mass, a small portion of global mean sealevel change originates from varying heat exchange between ocean and atmosphere, which cannot be related to a speciﬁc region. This eﬀect is at least one order of magnitude smaller than the sealevel change caused by the mass of the melt water inﬂow. It can be attributed to the non-linear nature of oceanic processes and may be regarded as a measure of uncertainty.
Fig. 6 (c&d) shows the depth and duration of flooding in the cases of a SLR of 1.0 m and 2.0 m above current sea levels. The influence of a 1.0 m SLR increases flood duration in the southern bank of the estuary, while the 2.0 m rise submerges most of the lower lands for more than 240 hours per month. This longer flood duration (in the 2.0 m scenario) has a number of serious consequences, which are, flooding and both villages are totally submerged for a duration 240 hours (apart from the area to the north of Ynyslas). Although high sand dunes protect the area, the unflooded areas could be blocked by water, and evacuation processes might be difficult, as flooding will cause disruption on the roads that connect the countryside and the coast. Failure of existing coastal defenses is because they are designed to withstand against 1/100 year event (4.14 m); therefore, rise of sealevel by 2 m increased mean sealevel to 4.85 m (AOD), as follows. The Borth Bog and other conservation sites are submerged and potentially destroyed. In Aberdyfi, the lowland coastal area at the mouth of the estuary is under extreme risk due to the insufficient height of existing sea defenses.
4 Study results
The study results presented here are based on a one-metre SLR, which is the basis of the inundation data adopted for the study. A sealevel rise of one metre will affect the existing estimated road infrastructure in Vietnam to the extent of 19,000 km of road infrastructure inundated and destroyed; just under 12 per cent of existing road infrastructure. This is a cost of approximately US$2.09 billion to replace the inundated infrastructure (Table 3). This is for all road types. The projected SLR is distributed unevenly, with the majority of damage affecting coastal regions in the southern part of the country. There are several provinces where a complete inundation is projected, resulting in a loss of at or near 100 per cent. These include Bac Lieu, Hau Giang, Soc Trang, Tra Vinh and Ca Mau. The ten most affected provinces are located in the Mekong River Delta region and have an average of 77 per cent of road infrastructure destroyed— a total of nearly 15,200 km. Figures 1-3 illustrate the percentage of road infrastructure damaged and total cost estimates at both regional and provincial levels. A full table of approximated damages can be seen in Appendix A.
Figure 1 presents the contribution to sea-level change resulting from the changes in the GIS following the LGM. We first examine the response when excluding the neoglaciation. The ice model (Fleming & Lambeck, 2004) defines the GIS as having reached its current extent by 7.5 ka BP. The signal is dominated by falling sea levels (crustal uplift), particularly pronounced in the southwest, east and north, where the GIS had expanded the most during the last glacial period relative to the present-day (Figure 1a, see also Le Meur & Huybrechts, 2001; Tarasov & Peltier, 2002). The maximum rates are of the order of -5 mm yr −1 , with the associated uncertainties,
Local geoid modeling, tide gauge data analysis, and the combination of all results in order to determine absolute sealevel heights has not been performed yet, as the primary goal at this stage is to identify first the achievable internal accuracies of the transponder positioning with the geodetic SAR technique. The processors for local geoid refinement and tide gauge data processing are already in place and tested. What is still missing is the identification of possible transponder related systematic effects, which could be visible in the positioning results. In conclusion, future work to be performed after having about one year of SAR observations available will include the following analyses: (1) Refinement of SAR positioning for phase center variations due to satellite-ground station geometry and electronic antenna behavior; (2) Relative SAR positioning and comparison to results from absolute positioning; (3) Calibration of transponder positioning versus GNSS positions and identification of possible systematic delays; (4) Local geoid refinement at the tide gauge stations; (5) Processing tide gauge observations with identical setup and applying same background models; (6) Transformation of coordinates from all three observation systems into a unique reference frame; (7) Computation of absolute sealevel heights at tide gauge stations and identification of possible systematic height system offsets between stations at two different countries; (8) Validation of height system differences by means of comparison to leveled heights at tide gauge stations.
countries lack abilities to mitigate climate change and instead try to incorporate physical and social hazards into their livelihoods as their coping mechanism (Mula 1999; Maxwell 1999; Meze-Hausken 2000; Findley 1994).
Pycroft, Abrell, and Ciscar (2015) estimate the impact of migration on GDP and find that the PRC, the Republic of Korea, and Indonesia have the highest estimated total impact among the region at a combined $6 billion, or almost 10% of the world’s estimates under the high scenario by 2080 (Table 2). Ericson et al. (2006) estimate that there are around 8.7 million people expected to be displaced by 2050 due to rising sea levels. ADB (2013) also reaches a similar conclusion, stating that SLR is projected to significantly impact the Pacific region, damaging infrastructure and human habitats. The ADB results are based on the IPCC Special Report on Emissions Scenarios and are interpreted as percentage deviations from a baseline situation without projected changes in climate conditions. The two integrated assessment models—Framework for Uncertainty, Negotiation and Distribution 3.6 (FUND3.6) and Policy Analysis of the Greenhouse Effect 09 (PAGE09)—estimate the total costs of climate change as a percentage of GDP increase every year. 8 Estimates from FUND3.6 indicate that
ABSTRACT: Sealevel rise (SLR) can give various impacts such as inundation in the low-lying areas, in- crease the coastal erosion and extreme events such as storm surge, wave overtopping, salt intrusion and damage to existing coastal infrastructure, hence affects the socio-economy and the livelihood of the coastal communities. The projected SLR along the Sandakan coast for the year 2020, 2040 and 2060 are 0.1 m, 0.25 m and 0.5 m, respectively. This study was carried out to assess the impacts of SLR to Sanda- kan coast for 2020, 2040 and 2060; and to recommend some relevant adaptation measures to reduce the impact. Hydrodynamic model with simulations of 2020 and 2040 projected SLR show no significant change in Sandakan Town when compared to the existing condition, probably due to its high platform level. However, model simulations for 2060 projected SLR show that the wave heights may increase by 0.18 m compared to the existing 2.6 m, although the wave heights in Teluk Sandakan will not change much. Similarly, the maximum current velocities will increase by 0.15 m/s in 2060, compared to the ex- isting condition of 0.3 - 0.5 m/s. Overall, more impacts of SLR can be observed at Pulau Duyong due to its low-lying area. There will be a reduction in land area; about 958 hectares out of the existing 1,800 hec- tares of mangrove forests and coastal vegetation will be lost due to inundation and erosion, generated by the 0.5 m projected SLR in 2060. Construction of railings, low walls and rock bunds are recommended as an adaptation measures to ensure the safety of the people living along the Sandakan coast. There is also a need to raise the bund and platform levels for jetties and slipways at the Marine Police Complex to avoid inundation. The estimated cost for the recommended adaptation measures is about RM18.25 Million.
The RSL height resulting from load model NAWI-A2 (Figures 5.4 and 5.5, solid lines) mainly decreases until 100 ka BP (SVM) or 110 ka BP (LVM) due to the viscoelastic relaxation following the previous deglaciation. Then, a further decrease is also caused by the glaciation of the northern hemisphere and the associated global sea-level fall. After 50 ka BP, the changes of the RSL height are dominated by the radial displace- ment induced by the increase of the ice load near Berkner Island. The minimum of the RSL height is reached at 56 ka BP (SVM, −141.4 m) or 51 ka BP (LVM, −80.9 m). Time of sediment deposition
ABSTRACT: Sealevel change is one of the main factors which cause major impacts along the global coastlines and it vary widely in the past few decades due to global warming. Global sealevel change is usually caused by melting of land-based ice and thermal expansion, as water warms. As the global warm- ing based sealevel rise (SLR) is alarming in ocean waters, it is increasingly important to assess the effect of the same in all the coastal processes. . In this study, the effects of SLR on the tidal hydrodynamics along the Gulf of Khambhat, India are investigated. Selected major diurnal and semi-diurnal constituents, M2, S2, N2, K1, O1 and P1, have been taken up for a detailed investigation through finite-element based numerical modelling, TELEMAC-2D. The numerical model results of the existing conditions are com- pared with available literature data and found to be in agreement. Tidal propagation is predicted for the above mentioned six tidal constituents with and without sealevel rise conditions. Three sealevel rise sce- narios (0.1m, 0.5m and 1m) had been adopted for the study. The amplitudes and velocities of individual constituents, extracted along a specific stretch of gulf were compared with that of no SLR condition, to obtain the percentage variations.
fine-grained Yellow River sediment and because its shore- line is situated on the broad shelf of the East China Sea (Fig. 1). During the Holocene sea-level rise the increasing water load in the west Pacific Ocean basin should have lifted the Bohai Sea shelf and pushed the shoreline landward, while the fluvial sediment input should have pushed the shoreline seaward. The two processes may have peaked at different times and their contrasting effect on shoreline migration may have varied accordingly. Beyond that, being situated in the far field, the shoreline should have migrated landward in re- sponse to the rising water level. The shelf effect and the ris- ing water level is well-described by sea-level physics, and the associated glacio-isostatic adjustment (GIA) models predict a sealevel elevated by up to 10 m height due to shelf lever- ing (e.g. Milne and Mitrovica, 2008). Indeed, a several-metre sea-level highstand is predicted for the East China Sea coast during the mid-Holocene (Bradley et al., 2016), but this high highstand seems to be an overestimate when compared to ob- servational data (Bradley et al., 2016) which indicate a mi- nor Holocene highstand for the East China Sea coast (Zong, 2004) and no obvious Holocene highstand for delta area of Yangtze River (Xiong et al., 2020) and the Pearl River delta (Xiong et al., 2018). From this the question arises whether the observational data are inaccurate, whether the GIA model parameters are too poorly constrained and how fluvial sedi- ment supply influences the sea-level history.
3.1 Do SLR’s scientists offer enough certainties to decision-takers? Let us consider an airport’s governance particularly aware about SLR. It intends planning future mitigating investments for the long term. For instance, airport may be located on the Mediterranean coast for near seashore airports (Barcelona (1m) or Nice (2-3m) or, still, Roma (Leonardo da Vinci, 3m). Let us assume that the planner prospects for the future forty years (2055). What are the factors he should take into considerations? Can he reasonably rule out the assumption of finding another location for a new airport? An appropriate answer to this question needs having a clear understanding of the SLR consequences. Indeed, the decision-maker faces several unknown data. Mainly, the analysis defines three scenarios. The first one corresponds to IPCC’s view that considers that the SLR does not exceed one meter during the 21 st century. The second one comes from scientists that raise doubts about it. This need considering then the three following points: i) The relevancy of the 2°C assumption, ii) Sea-level rise and past warm periods and, iii) The relevancy of semi-empirical models that deal with SLR.
methods are based on a combination of models and data, which are more useful when trying to estimate hazard extent where there is limited historical information. Methods for shoreline analysis vary in approach and accuracy. Delineating and using shoreline positions from photos to compute shoreline change analysis also require identification and quantification of biases and uncertainties associated with the shoreline position, such as photo resolution, georeferencing error, shoreline position error (tidal changes), and shoreline digitization error because these errors or uncertainties in turn influence the estimation of the shoreline change rate (Genz et al. 2007). These studies on coastal recession in Ghana have also lacked information on the contributions of regional SLR to coastal recession in Ghana, which to a large extent is a result of deficient historical tide gauge data for Ghana. Despite the questionable quality of historical tide gauge data, the National Oceanic and Atmospheric Administration (NOAA 2013), attempted to compute sea-level trends for the Takoradi tide gauge station in Ghana, yielding a rate of 2.16 ± 0.39 mm/y of relative SLR, taking into consideration only monthly tide gauge data covering the years 1929 to 1965, and some selected monthly records for 1992, 2007, 2008, and 2009 that were considered to provide accurate data. There is the need for more information on SLR, how SLR contributed to historical shoreline change in Ghana, and if possible the need for predictions of future shoreline in Ghana. The research purpose is to provide this useful information for coastal adaptation strategies by analyzing historical shoreline change for the entire Ghana coast, and quantify and predict the contribution of SLR to the shoreline change in Ghana.
Abed and Yaghan (2000) and Abed (2000) found it difficult to divide the Lisan Formation into members because these deposits are not the same in different parts of the lake. On the Lisan Peninsula, these deposits are chemical, consisting of grey aragonite laminae deposited in winter and white gypsum laminae deposited in summer. South of the Khunizera fault, the Lisan Formation consist of chemical laminae with sand. The Lisan Formation can be divided into three members only in the area between the north of the Dead Sea and Marma Feiyad: the Lower Laminated Member (15 m) consisting of interlaminated calcareous silt and aragonite, the Middle Member (9 m) consisting of massive black clay, and the Upper Laminated Unit (~18 m) consisting of interlaminated aragonite and silt (Fig. 1.4). The upper 5-7 m of this unit is a white cliff identical to the White Cliff of Begin et al. (1974). It consists of gypsum and aragonite, indicating a change to dry climatic conditions and a negative water balance within the Lake Lisan basin. Radiocarbon dating of the White Cliff sediments indicates that it accumulated between 33-15 ka BP (Kaufman, 1971) or 35-15 ka BP (Vogel and Waterbolk, 1972). Abed (2000) gave a younger age of 23-22 to 16-15 ka BP, depending on the sedimentation rate assumed. A similar age of about 24 cal ka BP was also derived by Landmann et al. (2002) based on a rough varve count. The two gypsum layers at the top of the sections in Massada Plain and Perazim Valley which may represent the White Cliff yielded an age of 17 cal ka BP (Stein, 2000; Stein et al., 1997; Bartov et al., 2002).
The costs of coastal sector impacts from sealevel rise (SLR) are an important component of the total projected economic damages of climate change, a major input to decision-making and design of climate policy. Moreover, the ultimate costs to coastal resources will depend strongly on adaptation, society’s response to cope with the impacts. This paper presents a new model to assess coastal impacts from SLR, combining global scope with high spatial resolution to fill a gap between very detailed local studies and aggregate global estimates. The Coastal Impact and Adaptation Model (CIAM) determines the optimal strategy for adaptation at the local level, evaluating over 12,000 coastal segments, as described in the DIVA database (Vafeidis et al, 2006), based on their socioeconomic characteristics and the potential impacts of relative sealevel rise and uncertain storm surge. An application of CIAM is then presented to demonstrate the model’s ability to assess local impacts and direct costs, choose the least-cost adaptation, and estimate global net damages for several probabilistic SLR scenarios (Kopp et al, 2014). CIAM finds that there is large potential for coastal adaptation to reduce the expected impacts of SLR compared to the alternative of no adaptation, lowering global net present costs by a factor of 10 to less than $1.5 trillion over the next two centuries, although this does not include initial transition costs to overcome an under-adapted current state. In addition to producing aggregate estimates, CIAM results can also be interpreted at the local level, where we find that retreat (e.g., relocate inland) is often a more cost-effective adaptation strategy than protect (e.g., construct physical defenses).
We further recall that gravity changes caused by GIA in the upper mantle need to be reduced from the GRACE data before interpreting the residuals as long-term changes in barystatic sealevel. The history of ice accumulation and melting on Earth during the last glacial cycle of approximately 120,000 years is a topic of ongoing research, and much progress has been made since the launch of GRACE both in terms of understanding the involved dynamics and modeling the present-day consequences (Whitehouse, 2018). Uncertainties in GIA forward models particularly arise from imprecise knowledge about the land ice history and the rheology of the Earth. For example, Li et al. (2018) combined global relative sealevel data, crustal uplift rates obtained from coordinate series of Global Navigational Satellite Systems (GNSS) receivers, and peak gravity rates from satellite gravimetry with the aim to find best fitting 3-D mantle viscosity models in Fennoscandia and Laurentia. By considering both GRACE mass balance estimates and present-day uplift rates from GNSS, van der Wal et al. (2015) evaluated GIA models for Antarctica to identify regions of highest model uncertainties.
Changes in tidal current velocities induced by sea-level rise are mostly compensated by the considered topographic changes of the Wadden Sea. The results demonstrate the significance of sea- level rise induced topographic changes in the Wadden Sea for estimating local effects of sea-level rise on tidal dynamics.