Potential Future Sea-level Rise Research Articles

Late-Holocene shoreline responses to competing shelf, bay, and beach accommodation spaces under conditions of relative sea level change, and the potential for future catastrophic beach retreat in the Columbia River Littoral Cell, Washington and Oregon, USA

The Columbia River Littoral Cell (CRLC) (160 km in length) provides opportunities to compare competing accommodation space relations under different conditions of relative sea level change. The CRLC system includes abundant littoral sand supply from the large Columbia River, late-Holocene prograded beach plains and barrier spits (0.5–5 km in width), two large marine-dominated estuaries (Willapa Bay and Grays Harbor), and a high-wave-energy inner-shelf. Littoral sand accumulation rates in prograded beach plains and barrier deposits are based on paleo-shoreline positions that are dated by great-earthquake catastrophic beach retreat scarps (n = 10) from 0.3 to 5.0 ka. The retreat scarp timelines are mapped in across-shore GPR transects (n = 79), yielding timeline-bounded polygons (n = 247). The polygons are evaluated for littoral sand volume and bounding ages, yielding volume accretion rates (m3 ka−1), which are summed for the four CRLC subcells; Clatsop Plains (27.4 × 106 m3 ka−1), Long Beach (19.8 × 106 m3 ka−1), Grayland Plains (15.9 × 106 m3 ka−1), North Beaches (11.7 × 106 m3 ka−1). Major submarine sinks of littoral sand, including the inner-shelf and large marine-dominated estuaries, are evaluated for increased littoral sand accommodation space that could result from potential future sea level rise of 1, 2 and 3 m during the next century or two. The estimated beach and nearshore sand erosion needed to fill the increased submarine accommodation space from a 2.0 m rise in relative sea level would result in averaged beach retreat values of ~0.7 km (Clatsop Plains), ~1.2 km (Long Beach), and ~ 1.3 km (Grayland Plains), about 30–50% larger than previous estimates based on the Brunn method. These catastrophic shoreline retreat distances (0.7–1.3 km) represent 25–50% of the present widths of prograded barrier spits and beach plains. They serve as warnings about future catastrophic beach erosion resulting from potential future SLR in other similar barrier spit and beach plain shorelines worldwide.

Modeling the combined impact of climate change and sea-level rise on general circulation and residence time in a semi-enclosed sea

This study provides an assessment of possible changes in the general circulation and residence time in the Persian Gulf under potential future sea-level rise and changes in the wind field due to the climate change. To determine the climate-change-induced impacts, Mike 3 Flow Model FM was used to simulate hydrodynamic and transport processes in the Persian Gulf in both historical (1998–2014) and future periods (2081–2100). Historical simulation was driven by ERA-Interim data. A statistical approach was employed to modify the values and directions of the future wind field obtained from the Representative Concentration Pathway 4.5 and 8.5 (RCP4.5 and RCP8.5, respectively) scenarios derived from CMCC-CM model of the fifth phase of the Coupled Model Intercomparison Project (CMIP5). The numerical model was calibrated and validated using measured data. Results indicated that in the historical period, residence time ranged between values of less than a month in the Strait of Hormuz and 10 years in the semi-enclosed area close to the south of Bahrain. The changes in wind field based on RCP 8.5 scenario were found to be the most disadvantageous for the Persian Gulf's capacity to flush dissolved pollutants out. Under this scenario, residence time would be 17% longer than that of historical one. This is mainly because the change in the wind field is large enough to overwhelm general circulation, showing a relationship between the residence time and the residual circulation. Impact of change in the wind field according to RCP 4.5 scenario on the modeled residence time is negligible. The numerical outputs also showed that the sea-level rise would slightly decrease the current velocity, resulting in a negligible increase in residence time. The findings of this study are intended to support establishing climate-adaptation management plans for coastal zones of the studied area in line with sustainable development goals.

Modeling migration patterns in the USA under sea level rise

Sea level rise in the United States will lead to large scale migration in the future. We propose a framework to examine future climate migration patterns using models of human migration. Our framework requires that we distinguish between historical versus climate driven migration and recognizes how the impacts of climate change can extend beyond the affected area. We apply our framework to simulate how migration, driven by sea level rise, differs from baseline migration patterns. Specifically, we couple a sea level rise model with a data-driven model of human migration and future population projections, creating a generalized joint model of climate driven migration that can be used to simulate population distributions under potential future sea level rise scenarios. The results of our case study suggest that the effects of sea level rise are pervasive, expanding beyond coastal areas via increased migration, and disproportionately affecting some areas of the United States.

Future sea level change from Antarctica's Lambert‐Amery glacial system

AbstractFuture global mean sea level (GMSL) change is dependent on the complex response of the Antarctic ice sheet to ongoing changes and feedbacks in the climate system. The Lambert‐Amery glacial system has been observed to be stable over the recent period yet is potentially at risk of rapid grounding line retreat and ice discharge given that a significant volume of its ice is grounded below sea level, making its future contribution to GMSL uncertain. Using a regional ice sheet model of the Lambert‐Amery system, we find that under a range of future warming and extreme scenarios, the simulated grounding line remains stable and does not trigger rapid mass loss from grounding line retreat. This allows for increased future accumulation to exceed the mass loss from ice dynamical changes. We suggest that the Lambert‐Amery glacial system will remain stable or gain ice mass and mitigate a portion of potential future sea level rise over the next 500 years, with a range of +3.6 to −117.5 mm GMSL equivalent.

Influence of Potential Future Sea-Level Rise on Tides in the China Sea

ABSTRACT Kuang, C.; Liang, H.; Mao, X.; Karney, B.; Gu, J.; Huang, H.; Chen, W., and Song, H., 2017. Influence of potential future sea-level rise on tides in the China Sea. This study investigates the diurnal and semidiurnal tidal responses of the entire China Sea to a potential rise in sea level of 0.5–2 m. A modified two-dimensional tidal model based on MIKE21 is primarily configured and validated for the present situation; then, three (0.5, 1, 2 m) sea-level rise (SLR) scenarios are simulated with this model. The predicted results show that the principal lunar semidiurnal (M2) and diurnal (K1) tidal constituents respond to SLR in a spatially nonuniform manner. Generally, changes of M2 and K1 amplitudes in shallow waters are larger than those in the deep sea, and significant tidal alterations mainly occur in the Bohai and Yellow seas, Jianghua Bay, Hangzhou Bay, Taiwan Strait, Yangtze River estuary, Pearl River estuary, and Beibu Bay. Possible mechanisms further discussed for these changes mainly relate...

Simulating the Impacts and Assessing the Vulnerability of the Central Artery/Tunnel System to Sea Level Rise and Increased Coastal Flooding

Highway tunnels along the coast are critical infrastructure and represent one of the more sensitive components of a transportation network to coastal flooding. By their very nature, large portions of these tunnels are beneath present sea level and the tunnel entrances and the equipment necessary to operate the tunnels such as vent buildings may or may not be above present flood thresholds. The Central Artery/Tunnel (CA/T) system in coastal Boston, Massachusetts USA is a vital link in the regional transportation network and is comprised of more than 160 lane-miles (more than half of them in tunnels), 6 interchanges and 200 bridges. While not examined here, the CA/T system relies upon other infrastructure systems to fully function, such as the electrical grid. The ADvanced CIRCulation model (ADCIRC) coupled with the Simulating WAves Nearshore (SWAN) Model was used for storm surge modeling. SLR scenarios were selected for four distinct time periods (2013, 2030, 2070, and 2100) to bracket the potential future sea level rise outcomes for the Boston Harbor area and a Monte Carlo statistical approach was utilized to estimate the probability of flooding throughout the Boston Harbor region. The vulnerability analysis was based solely upon exposure, defined as flooding experienced at CA/T systems when at the thresholds of the design flood standards that governed the original design of the CA/T. The extent of flood vulnerability under current climatic conditions is fairly limited with low exceedance probabilities. By late 21st century, however, there is considerable flooding at Tunnel Portals and other buildings and structures. Both local adaptation options such as flood walls protecting individual assets or gates protecting tunnel portals and regional plans blocking major flood pathways were evaluated. In complex systems such as the CA/T, the number and spatial extent of vulnerable areas increase over time as sea level rises and the intensity of storms increase, suggesting that local adaptations may be most applicable in the near-term and regional based adaptations (safeguarding multiple areas for multiple stakeholders) will become more cost effective and necessary solutions in the long-term. Focusing first on local actions also means that the CA/T owner is less reliant on other organizations and agencies to manage the CA/T adaptation as it will own the land necessary for any changes and will only have to manage its own efforts. The regional plan has the co-benefits that it will protect more assets in the region than just the CA/T and there is the possibility that the cost can be shared among more agencies and organizations than just the owner.

Numerical Assessment of the Impacts of Potential Future Sea‐Level Rise on Hydrodynamics of the Yangtze River Estuary, China

ABSTRACT Kuang, C.; Chen, W.; Gu, J.; Zhu, D.Z.; He, L., and Huang, H., 2014. Numerical assessment of the impacts of potential future sea‐level rise on hydrodynamics of the Yangtze River Estuary, China. Recent research suggests that sea levels are rising even faster than projected by the Intergovernmental Panel on Climate Change (IPCC). Under a sea level rise (SLR) scenario, estuarine and coastal areas would be affected first. In this paper, the effects on the Yangtze River Estuary (YRE) by potential future SLR are studied using a hydrodynamic (MIKE21) model. The model is calibrated with field data. Scenarios of 0.5, 1, and 2 m SLR in the flood season are simulated with the calibrated model. The predicted results show that under SLR (1) the tidal level of the YRE increases and its increase rate decreases gradually upstream along the channel; (2) the tidal wave propagates at a faster speed upstream, which leads to the advancement of a tidal limit and tidal current limit to the upstream; (3) the increases i...

A geological perspective on potential future sea-level rise

During ice-age cycles, continental ice volume kept pace with slow, multi-millennial scale, changes in climate forcing. Today, rapid greenhouse gas (GHG) increases have outpaced ice-volume responses, likely committing us to > 9 m of long-term sea-level rise (SLR). We portray a context of naturally precedented SLR from geological evidence, for comparison with historical observations and future projections. This context supports SLR of up to 0.9 (1.8) m by 2100 and 2.7 (5.0) m by 2200, relative to 2000, at 68% (95%) probability. Historical SLR observations and glaciological assessments track the upper 68% limit. Hence, modern change is rapid by past interglacial standards but within the range of ‘normal’ processes. The upper 95% limit offers a useful low probability/high risk value. Exceedance would require conditions without natural interglacial precedents, such as catastrophic ice-sheet collapse, or activation of major East Antarctic mass loss at sustained CO2 levels above 1000 ppmv.

Implications, Planning, and Design Considerations for Rising Sea Levels at the Coast

Implications, Planning, and Design Considerations for Rising Sea Levels at the Coast

Responses of estuarine salinity and transport processes to potential future sea-level rise in the Chesapeake Bay

Understanding the changes of hydrodynamics in estuaries with respect to magnitudes of sea-level rise is important to understanding the changes of biogeochemical processes that are coupled tightly with the physical processes. Based on the 21st century sea-level rise scenarios projected by the U.S. Climate Change Science Program (CCSP, 2009), the Chesapeake Bay was chosen as a prototype to study the responses of the estuary to potential future sea-level rise. The numerical model results show that the average salt content, salt intrusion length, and stratification will increase as sea level rises. The changes of these parameters have obvious seasonal and inter-annual variations. Both the salt content and stratification show more increase in spring (following the high-flow periods) and wet years than in autumn (following the low-flow periods) and dry years. The salt intrusion length has larger increase and greater standard deviation in autumn than in spring. The transport time scales are used to illustrate the variations of transport processes as sea level rises, and results indicate that (1) the exchange flow would be strengthened but the downstream transport of fresh water would be slower; (2) the residence time of the Bay would increase due to the increased volume and change of circulation; (3) the vertical transport time (reference to water surface) has more pronounced increase and the volume of water mass with different age groups increases with different rates. As a result, the retention time of dissolved substances in the Bay would increase. Although the increased tidal currents would strengthen the vertical mixing, the increased stratification would weaken the vertical exchange. The increase of vertical transport time is due to the impact of stratification changes, which overwhelms the impact of tidal changes. As the bottom dissolved oxygen (DO) supply is predominated by the vertical exchanges in the Chesapeake Bay, the increased upstream transport time has a weak impact on hypoxia conditions in the middle and upper portions of the Bay. The weakened vertical exchange would result in less DO supply from the surface to the bottom layer.

Διαχρονική παρατήρηση των μεταβολών της ακτογραμμής τμήματος της παράκτιας ζώνης του νόμου Πιερίας και εκτίμηση των επιπτώσεων από την μελλοντική άνοδο της θαλάσσιας στάθμης

The aim of this study is to detect shoreline changes along part of the coastal zone of Piena during the time period between 1969 and 2000 using aerial photographs and satellite images. Additionally, a quantitative and qualitative assessment of the future sea-level rise (triggered by the global climate change) implications to the physical and socioeconomic environment of the area is attempted taking into account various sea-level rise scenarios. Retreating as well as prograding regions along the study area were defined and retreating/prograding rates for the time periods 1969-1987 and 1987-2000 were estimated using GIS and Remote Sensing techniques. Building activity rates for the coastal area of Paralia Katerinis were also estimated for the same periods. The coastline of the study area is retreating^ except than the area north of torrent Mavroneri where a progradation rate of 48 cm/year was estimated between 1969 and 1987. Retreating rate of the coast for the northern part of the area (Saltworks) is estimated to be 25 cm/year and 19 cm/yrear for the periods of 1969-1987 and 1987-2000 respectively. The broader study area is particularly vulnerable to a potential future sealevel rise due to the low-lying topography of the coastal zone and intensive socioeconomic activities such as tourism and commerce.