The elevation of sealevel is not a constant level and changes over time. Since the last glacial maximum sealevel is generally rising, although with different rates. The industrial revolution and the related global warming, accelerated the rate of sea-levelrise. Precise predictions of future sea-levelrise are therefore essential for developing shoreline protection strategies. These predictions are calibrated to the sea-level highstand in past warmer climates and need consequently accurate estimates of the paleo sea levels. Besides the Holocene, the most studied past period in sealevel studies is the last major interglacial, the Marine Isotopic Stage (MIS) 5e between ca. 128 and 116 ka. During this period the global sealevel was 6-9 m higher than today with probably one or two rapid sea-level rises. The only direct observations of sealevel in this time, can be made by the investigation of paleo relative sea-level (RSL) indicators. Any geological feature with a quantifiable relation to the sealevel during the time of its formation can be used as RSL indicators. This relationship is called the indicative meaning and is quantified with two values: the distance between the feature and sealevel (i.e. the reference water level) and the possible, vertical variability (i.e. the indicative range). Studies of the MIS 5e sealevel have explored a large number of locations to assess the paleo sea-level elevation, but is currently facing five fundamental problems: (i) the measurement of RSL indicator elevations needs to be done always with the highest precision and referred to a defined tidal or geodetic datum; (ii) the indicative meaning needs to be utilized as standard procedure in all MIS 5e studies, as it is done for Holocene sea-level studies; (iii) the age attribution outside areas with fossil corals is often difficult and needs more research; (iv) the effects of post-depositional movements have to be attributed to all studies of RSL indicators; (v) in contrast to Holocene sea-level studies, MIS 5e studies are often lacking a stand- ardized structure to report their results.
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.
Sediment sources for the Elbe estuary are both from riverine and marine. The tidal Elbe River has a tendency for sedimentation due to the asymmetrical tide. On a very small scale locations can be found with alternating erosion and sedimentation. This is mainly due to morphological adjustments to human induced changes (dredging, fixing the shipping route, canalisation, land reclamation). Since the beginning of the last century, the Elbe estuary has been deepened several times to allow ships of increasing cargo capacities and draughts to reach the Port of Hamburg. The most recent deepening by about 1 m to 14.4 m depth was carried out during spring 1999. A further deepening to a depth of about 16 m along the whole longitudinal profile is recently planned. The objective of the deepening project is to allow vessels with an actual draught of 13.5m to use the Lower and Outer Elbe estuary without any tidal restrictions. Moreover, vessels with a draught of 14.5m must be able to enter and particularly leave the port with the corresponding tides. To create these improved access conditions the present fairway will have to be deepened by between 1.5m and 2.4m. However, as the present channel bed is above the required depth only in certain sections, the project will involve dredging only specific stretches of the Elbe estuary, and not the entire 130 km. In total, 38.5 million m³ of material will be dredged out of the channel, 75% of which will be used to build underwater structures, 22% will be relocated in the estuary and 3% will be used to charge and partly recharge polders (Osterwald et al., 2008). The morphology of the Elbe estuaries has been adapted by humans in order to optimize their function as shipping routes. Upstream, at the narrow end that leads into the docks, the channel was given a funnel like shape (Kausch, 1993). The canalization has resulted in a loss of intertidal and shallow sub tidal areas and in an increase of the tidal range (4 m at spring tide) in Hamburg. Other hydrological parameters like the diurnal asymmetry of the tides, the flow velocities during low and high tide (Kappenberg and Grabemann, 2001) are long‐term trends and cannot be associated with a specific deepening event. It is also found that the outer southern shore is mostly subjected to sedimentation. The northern coastline shows a constantly changing process of erosion and sedimentation.
Civil courts follow the same rules for global warming harm than for “usual” prejudices. Therefore, accepting the complainants’ request needs fulfilling three criteria. The first one is standing for adjudication (interest in acting) which associates the injury. The second one must highlight a causal link between harm and the polluters’ activities (causation). Finally, the third one consists in the tribunal jurisdiction’s ability to define remedies and relief. These three elements apply to civil courts (common law) as well as for administrative queries (statutory claims). In the United States, the standing question is linked to the nature of the damage. Accordingly, the Kivali village, in Alaska, argued that climate change highlighted the storms strength, the melting of the icebergs raised the water level and the shore erosion resulted in a deterioration of its inhabitant’s life quality. Plaintiffs questioned all the actors that they thought responsible for global warming as, primarily, EXXON Corporation and the major energy companies 16. In fact, this case falls within litigation which dismisses the plaintiffs’ claims. Indeed, these last ones have relied on Common Law which requires the accurate identification of those responsible in the reconstitution of the causal chain that was impossible here.
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 eustatic sealevel 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 sealevelrise, 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.
ature and salinity lead to density differences of water masses. Together with the circulation of the tides and the predominant wind pattern, these factors are responsible for the formation of currents. In the mean this results in a counter clockwise circulation in the North Sea. North West Europe is char- acterised by westerly winds, which enforce this circulation. However, strong easterly winds may occasionally turn this into a clockwise circulation (OSPAR Commission, 2000). The interaction of the tides and the meteorological surge, resulting from the wind and atmospheric pressure field determines the height of sealevel at a location to a specific time. If severe storms occur together with spring tide, this may result in an extreme sealevel. Coastal areas of the German Bight were often destroyed by storm surges. Within the last century, the most devastating storm surge occurred in February 1962. It especially affected the area around Hamburg. It took 340 lifes and destroyed many dikes and houses. Since then the coastal defense was systematically improved, but people are still threatened by a possible storm surge. The tidal cycle and the meteorological surge both change within hours, that is a storm surge is also an event of that time scale. A rise in the MSL means a higher base water level on which the tides and the meteorological surge act. This results in a higher risk for storm surges as the whole frequency distribution of water levels is shifted towards higher values.
For each estuary we apply an individually calibrated model. Figure 1 shows the model domains. The horizontal resolutions of the unstructured grids vary from a few metres to several hundreds of metres. At the seaward boundary we force the models with water levels and salinities extracted from a simulation with a North Sea model. The North Sea model is forced at the open boundary towards the North Atlantic by water levels composed of partial tides and constant salinities varying between 33 and 35 PSU along the boundary. For the period of simulation time we choose a period in summer 2006 which is character- ised by low wind velocities and rather low fresh water discharges. We apply observed values for the freshwater discharge entering the estuaries at the weirs. In the Elbe estuary fresh water discharge varies between 250 m³/s and 460 m³/s, in the Weser estuary it ranges from 126 m³/s to 159 m³/s, and in the Ems estuary freshwater discharge lies between 25 m³/s and 50 m³/s in the period analysed. The length of the simulations is at least two spring neap cycles. For the analyses only the last spring neap cycle simulated (20 July 2006 till 3 August 2006) is used. Compared with climate simulations, which usually simulate several decades, our simulation time periods are rather short. These short simulation time periods are pos- sible, because the modelled processes respond rapidly to changes of external drivers.
The salt concentration was found to be variable longitudinally, laterally and vertically. In the longitudinal direction, the concentration decreased from the D.S. towards the U.S. side. In the lateral direction, the higher the water depth the higher was the concentration. In the vertical direction, the concentration increased towards the bottom direction and clear stratification with a brackish water layer at the surface was noticed. The same three scenarios for the sealevelrise that were simulated in the 2D model were simulated also in the 3D model. The results revealed that the sealevelrise caused more propagation of saline water towards the Nile with values of 1.2 km, 5.1 km, and 6.6 km in case of sealevelrise of 0.24 m, 0.69 m and 1.0 m respectively. To mitigate the sealevelrise impact, discharging more water from Edfina Barrage could be required. The discharge of Edfina barrage will be increased by about 1.15, 3.67 and 5.88 BCM/year, such amount is considered as a considerable loss of the Egyptian water budget (55.5 BCM/year). Some compromises could be done in which more salt water intrusion can be allowed to a certain extent.
that model. It is assumed that the sealevel variability can be neglected in case of the 10-day constraint. Both the PCA model, made from five years of sealevel height data, and the PCA-CCA model, made from three years of sealevel height and sea surface temperature data, have an accuracy of about two centimetres. The accuracy of the extrapolated PCA-CCA model, constructed from three years of sealevel height data and from five years of sea surface temperature data using the sea surface temperature as the predictor, is lower, of about four centimetres, and still acceptable. It is concluded that the three SLA models are a good representation of the sealevel variability in the Mediterranean Sea at wavelengths longer than 50 kilometres and periods greater than 30 days. An additional reason for the interest on this test of accuracy, is that the DXO differences provide an estimate of the relative bias and drift between the two satellites, if the sealevel variability can be neglected or eliminated by a single-mission variability model. The observed drift in the DXO differences and their mean different from zero are interpreted as a relative bias and drift between ERS and T/P. The drift is due to a non homogeneous pre-processing of the ERS data, whereas the relative bias is related to ERS gravity induced orbit errors and has a geographical distribution. An interesting application of the extrapolated PCA-CCA model is the estimation of bias and drift between multi-mission data from not overlapping mission, as the usual method, based on DXO differences with a few days time difference constraint, is in that case not applicable. The single-mission sealevel height variability models are a first step towards the construction of multi-mission models, build from harmonised multi-mission sealevel height data to cover a longer time interval with increased spatial and temporal resolution.
The rate of geocentric sealevel change ˙g measured by altimetry in the period 1993-2001 is evaluated in each point of the grid through a least squares procedure by solving for the linear-term of the time-series of monthly averaged altimetric sealevel heights. The resulting ˙g is mostly positive in the European region and lower than 6 mm/yr except in the Ionian part of the Mediterranean Sea (up to 14 mm/yr) and in the eastern Atlantic Ocean at the location of the Gulf Stream. Higher values are observed in the eastern Mediterranean Sea (up to 10 mm/yr) and in the Black Sea (up to 14 mm/yr). The standard error of the linear-term of sealevel change is smaller than 3 mm/yr almost everywhere, it is higher than 4 mm/yr in the regions of high variability. The rate of geocentric sealevel change is dependent on the period analysed. Fig. F-09-3 shows the values in the Mediterranean Sea. The rate of vertical sealevel change relative to the Earth crust ˙s is evaluated over the same time interval 1993-2001 from monthly averages of tide gauge data at a set of stations in the Mediterranean Sea. The resulting ˙s is in general agreement with the altimetric results, with the positive highest values in the eastern Mediterranean and negative values along the southern Italian coasts (Fig. F- 09-4). Because of the different spatial and temporal sampling of altimetry and tide gauge data, care must be taken to match the hourly sealevel measurements made at the tide gauge stations with the 10-day sealevel measurements from Topex. In Nerem (Nerem and Mitchum, 2002) daily-averages at the tide gauge stations and up to eight passes of the altimeter were used, temporal and spatial lags were allowed before differencing the series and the altimetric height data were smoothed in the along track direction (Mitchum, 2002). Due to the local characteristics of sealevel variability and circulation in the semi-closed Mediterranean Sea, we use the absolute sealevel heights measured by satellite altimetry in the vicinity of each tide gauge station. For de-seasoned monthly and monthly averages the geocentric altimetric sealevel heights at the closed grid-point are used, while for near-simultaneous measurements the geocentric altimetric sealevel heights interpolated along-track to the nearest normal point are used. In this last case the differences in ocean tide and ocean circulation between the location of the tide gauge station and the altimeter point are neglected due to the small ocean tides and ocean circulation in the Mediterranean Sea. Five parameters are identified for the comparison between altimetry and tide gauge sealevel heights. They are: (1) the distance d at between
Abstract. In contrast to recent advances in projecting sea levels, estimations about the economic impact of sealevelrise are vague. Nonetheless, they are of great importance for policy making with regard to adaptation and greenhouse-gas mitigation. Since the damage is mainly caused by extreme events, we propose a stochastic framework to estimate the monetary losses from coastal floods in a confined region. For this purpose, we follow a Peak-over-Threshold approach em- ploying a Poisson point process and the Generalised Pareto Distribution. By considering the effect of sealevelrise as well as potential adaptation scenarios on the involved param- eters, we are able to study the development of the annual damage. An application to the city of Copenhagen shows that a doubling of losses can be expected from a mean sealevel increase of only 11 cm. In general, we find that for varying parameters the expected losses can be well approximated by one of three analytical expressions depending on the extreme value parameters. These findings reveal the complex inter- play of the involved parameters and allow conclusions of fun- damental relevance. For instance, we show that the damage typically increases faster than the sealevelrise itself. This in turn can be of great importance for the assessment of sealevelrise impacts on the global scale. Our results are accom- panied by an assessment of uncertainty, which reflects the stochastic nature of extreme events. While the absolute value of uncertainty about the flood damage increases with rising mean sea levels, we find that it decreases in relation to the expected damage.
The inner coastal waters are important regions for economic, ecologic and recreational purposes. They link the hinterland to the open sea as waterways, providing ports for regional traffic and medium sized shipyards are located there. Due to their protected location they are important ecosystems with a high di- versity of life. Their natural beauty attracts people to use them as recreational places both at the coastline and on the water. A sealevel change has influence on the behavior of the sealevel variability and on the exchange of properties of the water body of the inner waters with the Baltic Sea.
remote islands. Air and seaports are important hubs in the exchange of cargo and transfer of passengers in any logistic transport network. Once designed and constructed, seaports interfere with the local hydro- and morphodynamic system and potentially affect adjacent coastal areas. Small reef islands are particularly sensitive towards sea-levelrise and impacts due to coastal structures as implementation may increase their exposure and increase the vulnerability of the local population, if infrastructure development compromise or even imperil the natural equilibrium. This study documents and validates the erosion on the east coast of the Maldivian coral reef island of Fuvahmulah. Two numerical models help to identify the key drivers and interdependent processes of sediment transport on the coral reef and assess the port’s influence in aggravating formerly balanced sediment budgets. Our results highlight the significant susceptibility of reef islands in regard of inherent coastal processes as it calls for thoughtful investigations in the design stage prior to implementation of coastal infrastructures in order to avoid any misdesigning of seaports or even to maladaptation practices in remote islands.
regarded a legitimate route for the Contracting Partiesof the LDC to take,
some caveats should be expressed here. An amendment allowing sea-bed
implantation- of high-level radioactive waste should not be adopted until
reliable scientific studies are available confirming that the implanted wastes can really be isolated from the environment, and that there are no reason- able grounds f6r suspecting eventual damage to the environment. It would be irresponsible to take the other way, allowing sea-bed disposal of high- level radioactive wastes and to stop it only when there is evidence that risks are to be feared. It seems that the latter is a principle which is followed,by the Government of the United Kingdom with regard to dumping at sea3O ;
Besides, as another crucial factor inducing sea-level change in the Baltic Sea, the Glacial Isostatic Adjustment (GIA) – which is a consequence of the Scandinavian ice- sheet melting – leads to negative sea-level trends along the northern Baltic coast. The largest land uplift rates occur over the northern part of the Baltic Sea, and reach approximately 10 mm/year. However, the trend of vertical land movement is around of -1 mm/year at the south coast of Baltic Sea (Ekman 1996, Peltier 2004, Lidberg et al. 2010, Richter et al. 2011). Because of focusing on climate-induced sea-level variability in the Baltic Sea region, we need to remove the GIA effect from sea-level time series. Since the GIA-induced trend of the Baltic Sealevel is not varied even for a few centuries period, the GIA does not cause an anomaly in the sea-level for 11-year gliding trends. Therefore, as one of the lateral outcomes of the gliding trend method, we filter out the GIA effect from tide gauge time series by using decadal trend anomalies which are not modulated by the GIA-affected signal.
and 5.6b ). Coincidently, Knies et al. ( 1999 ) reported the high fluxes of CaCO 3 were found north of the Barents Sea resulted from the calving of ice margin, indicating the open-ocean area occurred along the northern Barents Sea margin blew off the Svalbard-Barents Sea Ice Sheet by katabatic winds and influenced by warm Atlantic Water advection. The relatively high concentrations of IP 25 at the northern Barents Sea continental margin and the West Spitsbergen margin reflect that the warm Atlantic water flowed into the Arctic along West Spitsbergen and continued eastwards along northern Barents Sea continental slope, which deduced some growth of ice algal and phytoplankton during spring and summer ( Figure 5.7b ). There were ice-free conditions in eastern Fram Strait during the LGM summer, supporting the reconstruction of LGM sea-ice extent based on foraminifer paleo-temperature estimates ( Sarnthein et al., 2003 ). This advance of Atlantic water has resulted in seasonally open-water conditions in Nordic Sea, which would have triggered the increasing evaporation and precipitation for the extension of ice sheets ( Hebbeln et al., 1994; Siegert et al., 2002; Ingólfsso and Landvik, 2013 ). Responding to these factors as well as lower summer insolation, the ice sheets have grown to maximum size by around 21 kyr BP ( Figure 5.7b ). Furthermore, a distant moisture source originating from the evaporation in the subtropics could also possibly contribute to LGM evolution ( Hebbeln et al., 1994 ). Low IP 25 concentration and zero-values of phytoplankton biomarkers in the north Fram Strait indicated that the summer sea-ice margin during LGM must have been located south of 81°N ( Müller et al., 2009 ), however, the sea ice only covered the western Fram Strait ( Sarthein et al., 2003 ). This is also supported by dinoflagellate cyst assemblages data indicating that dense sea-ice cover was restricted to the East Greenland continental margins ( de Vernal et al. , 2005 ). On the other hand, brassicasterol values here are much lower than those in the surface sediments due to the weakening Atlantic Water advection as the extent of Svalbard-Barents Sea Ice Sheet inhibited the Barents Sea branch of Atlantic water advection, and the Fram Strait branch was also restricted by the ice sheet, and permanent Arctic ice cover could not reach as far as it does today.
A recent assessment on the general performance of the two main direct extreme value analysis methods (i.e. the block maxima (BM) method and the peaks over threshold (POT) method) and their applicability to water level records in the German Bight was conducted in a companion study by A RNS et al. (2013). The return level and return period assessment in this paper is based on these recommendations. Results from that study showed that the POT method generally yields better results than the BM method if the model set-up is carefully chosen. The POT method is based on the assumption that the sample (i.e. all values above a threshold) is characterized by the generalized Pareto distri- bution (GPD). The POT sample is created choosing all values of a record that exceed a predefined threshold. The threshold selection is often subjective and this can potentially lead to different outcomes, especially when comparing the results from many sites along a coastline. In analyzing different threshold selection criteria, A RNS et al. (2013) showed that the 99.7 th percentile leads to stable and consistent results in the German Bight. Furthermore, it was shown that the storm surge of 1976 has to be included in the statisti- cal analyses; this event was the highest one ever recorded in large parts of the German Bight. The approach recommended by A RNS et al. (2013) for estimating return levels in the German Bight with minimal subjectivity comprises the following steps:
As flow separation inside the main engine nozzle causes undesired side loads with an amplitude of up to several percent of the engine thrust , it has to be avoided during sea-level operation. This constraint limits the nozzle area ratio. But, as the ambient pressure decreases during ascent of the launcher, a higher nozzle area ratio without flow separation would be possible. This would enable a higher specific impulse, leading to an increase of payload mass.