Reflections on the decadal-scale response of coastal cliffs to sea-level rise

Beaches form a significant component of the economy, history, and culture of southern California. Yet both the construction of dams and debris basins in coastal watersheds and the armoring of eroding coastal cliffs and bluffs have reduced sand supply. Ultimately, most of this beach sand is permanently lost to the submarine canyons that intercept littoral drift moving along this intensively used shoreline. Each decade the volume of lost sand is enough to build a beach 100 feet wide, 10 feet deep and 20 miles long, or a continuous beach extending from Newport Bay to San Clemente. Sea-level rise will negatively impact the beaches of southern California further, specifically those with back beach barriers such as seawalls, revetments, homes, businesses, highways, or railroads. Over 75% of the beaches in southern California are retained by structures, whether natural or artificial, and groin fields built decades ago have been important for local beach growth and stabilization efforts. While groins have been generally discouraged in recent decades in California, and there are important engineering and environmental considerations involved prior to any groin construction, the potential benefits are quite large for the intensively used beaches and growing population of southern California, particularly in light of predicted sea-level rise and public beach loss. All things considered, in many areas groins or groin fields may well meet the objectives of the California Coastal Act, which governs coastal land-use decisions. There are a number of shoreline areas in southern California where sand is in short supply, beaches are narrow, beach usage is high, and where sand retention structures could be used to widen or stabilize local beaches before sand is funneled offshore by submarine canyons intercepting littoral drift. Stabilizing and widening the beaches would add valuable recreational area, support beach ecology, provide a buffer for back beach infrastructure or development, and slow the impacts of a rising sea level.

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Decadal-scale onset and termination of Antarctic ice-mass loss during the last deglaciation

Nature Communications ◽

10.1038/s41467-021-27053-6 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Michael E. Weber ◽

Nicholas R. Golledge ◽

Chris J. Fogwill ◽

Chris S. M. Turney ◽

Zoë A. Thomas

Keyword(s):

Mass Loss ◽

Sea Level Rise ◽

Sea Level ◽

Ross Sea ◽

Ice Sheet ◽

Rate Of Change ◽

Last Deglaciation ◽

Decadal Scale ◽

Ice Sheet Modeling ◽

Global Sea Level

AbstractEmerging ice-sheet modeling suggests once initiated, retreat of the Antarctic Ice Sheet (AIS) can continue for centuries. Unfortunately, the short observational record cannot resolve the tipping points, rate of change, and timescale of responses. Iceberg-rafted debris data from Iceberg Alley identify eight retreat phases after the Last Glacial Maximum that each destabilized the AIS within a decade, contributing to global sea-level rise for centuries to a millennium, which subsequently re-stabilized equally rapidly. This dynamic response of the AIS is supported by (i) a West Antarctic blue ice record of ice-elevation drawdown >600 m during three such retreat events related to globally recognized deglacial meltwater pulses, (ii) step-wise retreat up to 400 km across the Ross Sea shelf, (iii) independent ice sheet modeling, and (iv) tipping point analysis. Our findings are consistent with a growing body of evidence suggesting the recent acceleration of AIS mass loss may mark the beginning of a prolonged period of ice sheet retreat and substantial global sea level rise.

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Sea level rise in the Venetian lagoon inferred from the 150-year-long tidal record

10.5194/egusphere-egu2020-1046 ◽

2020 ◽

Author(s):

Sara Rubinetti ◽

Carla Taricco ◽

Davide Zanchettin ◽

Enrico Arnone ◽

Angelo Rubino

Keyword(s):

Time Series ◽

Sea Level Rise ◽

Sea Level ◽

City Centre ◽

Reference Level ◽

Decadal Scale ◽

Historical Series ◽

Venetian Lagoon ◽

The City

The city of Venice (Northern Italy), together with its lagoon, is a historic, cultural and artistic heritage of inestimable value. One of its peculiarities consists in the recurrent storm surge phenomena, referred to as acqua alta. Sea level rise and local subsidence made their frequency to increase dramatically with respect to the past, causing severe damages to the lagoon and in particular to the city centre, as during the exceptional high tide verified on November 12, 2019. Here we show the analysis of the historical time series of tidal maxima and minima recorded in the Venetian lagoon, covering the period 1872-2018. It is the longest and most complete historical series of the Venetian area and one of the longest records of the entire Mediterranean region. During this period, the relative sea level height has increased of about 30 cm with respect to the reference level, while the average number of acqua alta events &#8211; evaluated over a 40-year time interval - has passed from about 4 to 70 per year. These events usually occur during the fall season (from October to December), even if a not negligible number has been also recorded during winter. Therefore, we analyse the October-March average annual time series with advanced spectral analysis methods, like Monte Carlo Singular Spectrum Analysis (MC-SSA), to extract and reconstruct the significant variability modes characterizing the record. They are the increasing long-term trend and components with multidecadal, decadal and interannual periods. The trend results from the superposition on the global eustacy of the local subsidence affecting the Venetian lagoon, which is due to both natural causes and human activities. We also discuss the possible linkage of the other significant spectral components to large scale climatic patterns. In particular, the decadal-scale oscillation is one of the most important variability modes affecting Northern Italian hydrology. Finally, we apply simple statistical methods (autoregressive models and feed-forward neural networks) to forecast the long-term evolution of sea level over the next ten years. In this contribution, we illustrate results from this state of the art two-fold statistical prediction system that provides robust predictions of sea level in the Venetian lagoon for the next decade and discuss them in the light of current longer-term projections of future sea level rise. Finally, we will test the predictive skill of the applied methods using tidal measurements recorded during 2019, to verify if our predictions are able to describe tidal variability characterizing the current year. &#160; &#160; &#160;&#160;

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Event and decadal-scale modeling of barrier island restoration designs for decision support

Shore & Beach ◽

10.34237/1008816 ◽

2020 ◽

pp. 49-57

Author(s):

Joseph Long ◽

P. Soupy Dalyander ◽

Michael Poff ◽

Brian Spears ◽

Brett Borne ◽

...

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Water Levels ◽

Storm Events ◽

Model Framework ◽

Modeling Framework ◽

Dune System ◽

Island Restoration ◽

Decadal Scale ◽

Wide Range

An interdisciplinary project team was convened to develop a modeling framework that simulates the potential impacts of storms and sea level-rise to habitat availability at Breton Island, Louisiana, for existing conditions and potential future restoration designs. The model framework was iteratively developed through evaluation of model results at multiple checkpoints. A methodology was developed for characterizing regional wave and water levels, and the numerical model XBeach was used to simulate the potential impacts from a wide range of storm events. Simulations quantified the potential for erosion, overwash, and inundation of the pre- and post-restoration beach and dune system and were used as a preliminary screening of restoration designs. The model framework also incorporated a computationally efficient method to evaluate the impacts of storms, long-term shoreline changes, and relative sea level rise over a 15-year time period, in order to evaluate the effect of the preferred restoration alternative on habitat distribution. Results directly informed engineering design decisions and expedited later project stages including the construction permitting process.

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Using a CMIP5 multi-model ensemble to model glacier mass balance on decadal scales

10.5194/egusphere-egu21-10047 ◽

2021 ◽

Author(s):

Larissa van der Laan ◽

Kristian Förster ◽

Fabien Maussion ◽

Adam Scaife

Keyword(s):

Mass Balance ◽

Sea Level Rise ◽

Sea Level ◽

Time Scale ◽

Water Resource Management ◽

Glacier Mass Balance ◽

Spatial And Temporal Scales ◽

Decadal Scale ◽

Model Ensembles ◽

Decadal Climate

Glaciers fulfil several important roles in the earth system, including being clear indicators of climate change and providing essential freshwater storage and downstream runoff to 22% of the global population. In addition, they are the main contributors to sea level rise and are expected to remain so throughout the 21st Century. In order to monitor glacier development, observing and predicting glacier mass balance on different spatial and temporal scales is essential. The current study aims to improve the understanding of glacier mass balance prediction on the decadal scale (5-15 years), a rarely studied time scale in the context of glaciers, but if reliable, highly applicable for glacier related water resource management and sea level rise predictions. This is achieved through the use of CMIP5 decadal climate prediction multi-model ensembles (reforecasts) to force the mass balance component of the Open Global Glacier Model (OGGM). This method is applied to 254 reference glaciers, distributed throughout 17 of the 19 Randolph Glacier Inventory (RGI) regions. The reforecasts are initialized in 1960 and 1980 and bias corrected to the glacier scale. The following statistical analysis then gives a good indication of the skill of climate reforecasts in mass balance modelling on this glacier atypical time scale.

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Decadal-scale onset and termination of Antarctic ice-mass loss during the last deglaciation

10.5194/egusphere-egu21-3385 ◽

2021 ◽

Author(s):

Michael E. Weber ◽

Nicholas R. Golledge ◽

Christopher J. Fogwill ◽

Chris S.M. Turney ◽

Zoë A. Thomas

Keyword(s):

Mass Loss ◽

Sea Level Rise ◽

Sea Level ◽

Ice Sheet ◽

Rate Of Change ◽

Ice Age ◽

Last Deglaciation ◽

Antarctic Ice Sheet ◽

Decadal Scale ◽

Global Sea Level

Emerging evidence suggests retreat of the Antarctic Ice Sheet (AIS) can persist considerably longer than the duration of the forcing. Unfortunately, the short observational record cannot resolve the tipping points, rate of change, and responses on century and longer timescales. New data from Iceberg Alley identifies eight retreat phases after the last Ice Age that de-stabilized the AIS within a decade, contributing to global sea-level rise for centuries to a millennium, which subsequently stabilized equally rapidly. New blue ice records and independent ice-sheet modeling demonstrate the dynamic response of the AIS included a step-wise retreat of up to 400&#160;km across the Ross Sea, accompanied by ice elevation drawdown of the West Antarctic Ice Sheet (>600&#160;m). Together, these long time series support studies that propose the recent acceleration of AIS mass loss may mark the beginning of a prolonged period of ice sheet retreat, associated with substantial global sea level rise.

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Modeling assessment of a saltwater intrusion and a transport time scale response to sea-level rise in a tidal estuary

Environmental Fluid Mechanics ◽

10.1007/s10652-014-9367-y ◽

2014 ◽

Vol 15 (3) ◽

pp. 491-514 ◽

Cited By ~ 19

Author(s):

Wei-Bo Chen ◽

Wen-Cheng Liu ◽

Ming-Hsi Hsu

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Time Scale ◽

Saltwater Intrusion ◽

Transport Time ◽

Tidal Estuary ◽

Scale Response ◽

Transport Time Scale

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Sea-level rise and other influences on decadal-scale salinity variability in a coastal plain estuary

Estuarine Coastal and Shelf Science ◽

10.1016/j.ecss.2015.01.022 ◽

2015 ◽

Vol 157 ◽

pp. 79-92 ◽

Cited By ~ 32

Author(s):

Andrew C. Ross ◽

Raymond G. Najjar ◽

Ming Li ◽

Michael E. Mann ◽

Susan E. Ford ◽

...

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Coastal Plain ◽

Salinity Variability ◽

Coastal Plain Estuary ◽

Decadal Scale

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ASSESSING PRESENT AND FUTURE MEDITERRANEAN SEA LEVEL RISE IMPACT ON ISRAEL’S COAST AND MITIGATION WAYS AGAINST BEACH AND CLIFF EROSION

Coastal Engineering Proceedings ◽

10.9753/icce.v32.management.4 ◽

2011 ◽

Vol 1 (32) ◽

pp. 4 ◽

Cited By ~ 2

Author(s):

Sergiu Dov Rosen

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Numerical Models ◽

National Policy ◽

Relative Sensitivity ◽

Mediterranean Coast ◽

Policy Document ◽

Sea Levels ◽

Model Study ◽

Coastal Cliffs

This paper presents the outcome of a coastal engineering hydro and morpho-dynamic model study using a number of numerical models which was conducted by the author on the erosion state of the Mediterranean coast of Israel for a time horizon of 100 years. The study assessed future sea levels, and compared wave setup and runup and beach profile erosion at the coastal cliffs in order to determine the relative sensitivity of the various coastal sectors of the Israeli shore. Finally it investigated measures and means for effective the mitigation of the forecasted beach and cliff erosion. The study was carried out as part of a multi disciplinary work involving various additional disciplines, and was used to establish a national policy document in regards to the coastal cliffs collapse and erosion by natural and anthropogenic induced factors, including global warming induced sea level rise and reduced return period of extreme events. The approach and outcomes are estimated to be useful for coasts of similar conditions elsewhere on the globe.

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SEA-LEVEL EFFECT ON ANNUAL CYCLIC BEACH MORPHOLOGY IN SWASH ZONE AT HASAKI COAST

Coastal Engineering Proceedings ◽

10.9753/icce.v36.sediment.35 ◽

2018 ◽

pp. 35

Author(s):

Masayuki Banno ◽

Yoshiaki Kuriyama

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Observation Data ◽

Swash Zone ◽

Beach Profile ◽

Beach Morphology ◽

Bruun Rule ◽

Decadal Scale ◽

And Sea Level

depend on the accurate knowledge of the beach response to sea level regime on multi-time scale. For the long-term beach response, Bruun (1962) suggested that the equilibrium beach profile would move to new equilibrium profile in response to a rising sea level. In this concept called as Bruun rule, the upper part of the beach profile is eroded due to the sea level rise, resulting in the shoreline retreat. It is widely used for the future shoreline prediction. However, the Bruun rule predicts just only the final beach state with a constant wave impinging for an infinite period after sea level rise. On the other hand, simultaneous function of wave and sea level is more important on interannual to decadal-scale beach response. El niÃ±o in 2015 and 2016 increased wave energy and sea level, corresponding to large beach erosion across the US west coast (Barnard et al., 2017). Sea level influences the response sensitivity to the wave forcing as a subordinate factor on the morphological change. High water level anomalies made the beach more eroded even if the wave condition was equal. Beach morphology in the swash zone often changes on a 1-year cycle due to seasonal wave conditions. The effect of sea level on the annual cyclic beach morphology in swash zone is still unclear because long-term beach observation data required for the analysis are difficult to obtain. In this study, we investigated the simultaneous effects of the wave and sea level on annual cyclic beach morphology in the swash zone with spectrum analysis for 25-year Hasaki beach observation data.

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