scholarly journals Projection of future sea level rise in the East Asian Seas based on Global Ocean-Sea Ice Coupled Model with SRES A1B Scenario

2021 ◽  
Vol 8 (4) ◽  
pp. 281-286
Author(s):  
Minwoo Kim ◽  
Cheol-Ho Kim ◽  
Chan Joo Jang

To project the future sea level rise in the East Asian Seas due to global warming, regional sea level variations are downscaled from three climate system models (GFDL-CM2.1, ECHAM5/MPI-OM, MIROC3.2(hires)) using a global ocean-sea ice coupled model with non-Boussinesq approximation. Based on the SRES A1B Scenario, the projected ensemble mean sea level rise (rate of rise) for the East Sea, Yellow Sea and East China Sea from 1995 to 2050 is 15.60cm (2.84mm/year), 16.49cm (3.0mm/year) and 16.43cm (2.99mm/year), respectively. With the inclusion of the future change of land ice melting and land water storage, the mean sea level rise (rate of rise) increases to 33.55cm (6.10mm/year) for the East Sea, and 34.38~34.44cm (6.25~6.26mm/year) for the Yellow and East China Seas. The present non-Boussinesq ocean model experiment shows that the future sea level rise in the East Sea is mainly due to the steric component changes by heat content increase. On the other hand, the future sea level rise in the Yellow and East China Seas appears to be mainly associated with the non-steric component change by water mass convergence.

2021 ◽  
Vol 15 (2) ◽  
pp. 1015-1030 ◽  
Author(s):  
Aurélien Quiquet ◽  
Christophe Dumas

Abstract. Polar amplification will result in amplified temperature changes in the Arctic with respect to the rest of the globe, making the Greenland ice sheet particularly vulnerable to global warming. While the ice sheet has been showing an increased mass loss in the past decades, its contribution to global sea level rise in the future is of primary importance since it is at present the largest single-source contribution after the thermosteric contribution. The question of the fate of the Greenland and Antarctic ice sheets for the next century has recently gathered various ice sheet models in a common framework within the Ice Sheet Model Intercomparison Project for the Coupled Model Intercomparison Project – phase 6 (ISMIP6). While in a companion paper we present the GRISLI-LSCE (Grenoble Ice Sheet and Land Ice model of the Laboratoire des Sciences du Climat et de l'Environnement) contribution to ISMIP6-Antarctica, we present here the GRISLI-LSCE contribution to ISMIP6-Greenland. We show an important spread in the simulated Greenland ice loss in the future depending on the climate forcing used. The contribution of the ice sheet to global sea level rise in 2100 can thus be from as low as 20 mm sea level equivalent (SLE) to as high as 160 mm SLE. Amongst the models tested in ISMIP6, the Coupled Model Intercomparison Project – phase 6 (CMIP6) models produce larger ice sheet retreat than their CMIP5 counterparts. Low-emission scenarios in the future drastically reduce the ice mass loss. The oceanic forcing contributes to about 10 mm SLE in 2100 in our simulations. In addition, the dynamical contribution to ice thickness change is small compared to the impact of surface mass balance. This suggests that mass loss is mostly driven by atmospheric warming and associated ablation at the ice sheet margin. With additional sensitivity experiments we also show that the spread in mass loss is only weakly affected by the choice of the ice sheet model mechanical parameters.


2020 ◽  
Vol 8 (1) ◽  
pp. 42
Author(s):  
Richard Marijnissen ◽  
Matthijs Kok ◽  
Carolien Kroeze ◽  
Jantsje van Loon-Steensma

Integrating natural components in flood defence infrastructure can add resilience to sea-level rise. Natural foreshores can keep pace with sea-level rise by accumulating sediment and attenuate waves before reaching the adjacent flood defences. In this study we address how natural foreshores affect the future need for dike heightening. A simplified model of vertical marsh accretion was combined with a wave model and a probabilistic evaluation of dike failure by overtopping. The sensitivity of a marsh-dike system was evaluated in relation to a combination of processes: (1) sea-level rise, (2) changes in sediment concentration, (3) a retreat of the marsh edge, and (4) compaction of the marsh. Results indicate that foreshore processes considerably affect the need for dike heightening in the future. At a low sea-level rise rate, the marshes can accrete such that dike heightening is partially mitigated. But with sea-level rise accelerating, a threshold is reached where dike heightening needs to compensate for the loss of marshes, and for increasing water levels. The level of the threshold depends mostly on the delivery of sediment and degree of compaction on the marsh; with sufficient width of the marsh, lateral erosion only has a minor effect. The study shows how processes and practices that hamper or enhance marsh development today exacerbate or alleviate the challenge of flood protection posed by accelerated sea-level rise.


2021 ◽  
Author(s):  
Hyeonsoo Cha ◽  
Jae-Hong Moon ◽  
Taekyun Kim ◽  
Yuhe Tony Song

Abstract Recent advances in satellite measurements and ocean heat-content estimates have enabled the monitoring of global mean sea level (GMSL) budget components and understanding of ocean effects on the Earth’s energy imbalance and hydrology. We observed a notable accelerating GMSL rise rate in the recent decade after the warming “hiatus” during the 2000s, and demonstrated that this was attributed to decade-long shifts in ocean heat storage and hydrology. Since ~2011, climate-driven changes have resulted in additional ocean mass gain (271±89 Gt yr-1) from glacier-free land water storage and increased ocean heat uptake (0.28±0.17 W m-2), accelerating the GMSL rise rate by 1.4±0.4 mm yr-1. The suggested estimates of sea-level and Earth’s energy budgets highlight the importance of natural variability in understanding the impacts of the ongoing sea-level rise.


2020 ◽  
Author(s):  
Piero Lionello ◽  
David Barriopedro ◽  
Christian Ferrarin ◽  
Robert J. Nicholls ◽  
Mirko Orlic ◽  
...  

Abstract. Floods in the Venice city centre result from the superposition of several factors: astronomical tides, seiches and atmospherically forced fluctuations, which include storm surges, meteotsunamis, and surges caused by planetary waves. All these factors can contribute to positive sea-level anomalies individually and can also result in extreme sea-level events when they act constructively. The largest extreme sea level events have been mostly caused by storm surges produced by the Sirocco winds. This leads to a characteristic seasonal cycle, with the largest and most frequent events occurring from November to March. Storm surges can be produced by cyclones whose centers are located either north or south of the Alps. The most intense historical events have been produced by cyclogenesis in the western Mediterranean, to the west of the main cyclogenetic area of the Mediterranean region in the Gulf of Genoa. Only a small fraction of the interannual variability of extreme sea levels is described by fluctuations in the dominant patterns of atmospheric circulation variability over the Euro-Atlantic sector. Therefore, decadal fluctuations of sea-level extremes remain largely unexplained. In particular, the effect of the 11-year solar cycle appears to be small, non-stationary or masked by other factors. The historic increase in the frequency of extreme sea levels since the mid 19th Century is explained by relative sea level rise, with no long term trend in the intensity of the atmospheric forcing. Analogously, future regional relative mean sea level rise will be the most important driver of increasing duration and intensity of Venice floods through this century, overwhelming the small decrease in marine storminess projected during the 21 century. Consequently, the future increase of extreme sea levels covers a large range, partly reflecting the highly uncertain mass contributions to future mean sea level rise from the melting of Antarctica and Greenland ice-sheets, especially towards the end of the century. In conclusion, for a high emission scenario the magnitude of 1-in-100 year sea level events at the North Adriatic coast is projected to increase up to 65 % and 160 % in 2050 and 2100, respectively, with respect to the present value, and subject to continued increase thereafter. Local subsidence can further contribute to the future increase of extreme sea levels. This analysis shows the need for adaptive planning of coastal defenses with solutions that can be adopted to face the large range of plausible future sea-level extremes.


2021 ◽  
Vol 21 (8) ◽  
pp. 2705-2731 ◽  
Author(s):  
Piero Lionello ◽  
David Barriopedro ◽  
Christian Ferrarin ◽  
Robert J. Nicholls ◽  
Mirko Orlić ◽  
...  

Abstract. Floods in the Venice city centre result from the superposition of several factors: astronomical tides; seiches; and atmospherically forced fluctuations, which include storm surges, meteotsunamis, and surges caused by atmospheric planetary waves. All these factors can contribute to positive water height anomalies individually and can increase the probability of extreme events when they act constructively. The largest extreme water heights are mostly caused by the storm surges produced by the sirocco winds, leading to a characteristic seasonal cycle, with the largest and most frequent events occurring from November to March. Storm surges can be produced by cyclones whose centres are located either north or south of the Alps. Historically, the most intense events have been produced by cyclogenesis in the western Mediterranean, to the west of the main cyclogenetic area of the Mediterranean region in the Gulf of Genoa. Only a small fraction of the inter-annual variability in extreme water heights is described by fluctuations in the dominant patterns of atmospheric circulation variability over the Euro-Atlantic sector. Therefore, decadal fluctuations in water height extremes remain largely unexplained. In particular, the effect of the 11-year solar cycle does not appear to be steadily present if more than 100 years of observations are considered. The historic increase in the frequency of floods since the mid-19th century is explained by relative mean sea level rise. Analogously, future regional relative mean sea level rise will be the most important driver of increasing duration and intensity of Venice floods through this century, overcompensating for the small projected decrease in marine storminess. The future increase in extreme water heights covers a wide range, largely reflecting the highly uncertain mass contributions to future mean sea level rise from the melting of Antarctica and Greenland ice sheets, especially towards the end of the century. For a high-emission scenario (RCP8.5), the magnitude of 1-in-100-year water height values at the northern Adriatic coast is projected to increase by 26–35 cm by 2050 and by 53–171 cm by 2100 with respect to the present value and is subject to continued increase thereafter. For a moderate-emission scenario (RCP4.5), these values are 12–17 cm by 2050 and 24–56 cm by 2100. Local subsidence (which is not included in these estimates) will further contribute to the future increase in extreme water heights. This analysis shows the need for adaptive long-term planning of coastal defences using flexible solutions that are appropriate across the large range of plausible future water height extremes.


2021 ◽  
Vol 9 (2) ◽  
pp. 205
Author(s):  
Serafino Afonso Rui Mucova ◽  
Ulisses Miranda Azeiteiro ◽  
Walter Leal Filho ◽  
Carina Lurdes Lopes ◽  
João Miguel Dias ◽  
...  

Mean sea-level is expected to rise significantly by 2100 in all scenarios, including those compatible with the objectives of the Paris Climate Agreement. Global sea level rise projections indicate devastating implications for populations, ecosystem services and biodiversity. The implications of the sea-level rise (SLR) on low-lying islands and coastal regions and communities are substantial and require deep-rooted coping measures. In the absence of adequate responses for coping, Mozambique is expected to record huge losses, with an impact on the economy and development in many sectors of its coastal regions mainly in northern Mozambique. This research aimed to perform projections on SLR in Mozambique, and to understand its role and implications on the north coast of the country. SLR was estimated through the analysis of model outputs that support the global estimates of the fifth IPCC report near the Mozambican coast, for each of the four representative concentration pathways (RCPs) scenarios. Regional coastline retreat and coastal erosion were estimated through the results of global sandy coastlines projections developed by Vousdoukas. Mean sea-level rise projections indicate that regional estimates for the Mozambican coast are relative higher than global estimates (~0.05 m) for all representative concentration pathways (RCPs). Yet, we highlight significant differences in sea-level rises of 0.5 m, 0.7 m or 1.0 m by 2100 compared to the global mean. It is expected that with the increase in the mean sea level in the northern part of the Mozambican coast, erosive effects will increase, as well as the retreat of the coastline until 2100. With this, the tourism sector, settlements, ecosystem services and local populations are expected to be significantly affected by 2050, with increased threats in 2100 (RCP4.5, RCP8.5). Local responses for coping are proposed and properly discussed for the RCP4.5 and RCP8.5 scenarios through 2100.


Atmosphere ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 95
Author(s):  
Phil J. Watson

This paper provides an Extreme Value Analysis (EVA) of the hourly water level record at Fort Denison dating back to 1915 to understand the statistical likelihood of the combination of high predicted tides and the more dynamic influences that can drive ocean water levels higher at the coast. The analysis is based on the Peaks-Over-Threshold (POT) method using a fitted Generalised Pareto Distribution (GPD) function to estimate extreme hourly heights above mean sea level. The analysis highlights the impact of the 1974 East Coast Low event and rarity of the associated measured water level above mean sea level at Sydney, with an estimated return period exceeding 1000 years. Extreme hourly predictions are integrated with future projections of sea level rise to provide estimates of relevant still water levels at 2050, 2070 and 2100 for a range of return periods (1 to 1000 years) for use in coastal zone management, design, and sea level rise adaptation planning along the NSW coastline. The analytical procedures described provide a step-by-step guide for practitioners on how to develop similar baseline information from any long tide gauge record and the associated limitations and key sensitivities that must be understood and appreciated in applying EVA.


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