Coastal flood damage and adaptation costs under 21st century sea-level rise

Global scale assessment of coastal flood damage and adaptation costs under 21st century sea-level rise are associated with a wide range of uncertainties including those in future projections of socioeconomic development (SSP scenarios), of greenhouse gas emissions (RCP scenarios), and of sea-level rise (SLR). These uncertainties also include structural uncertainties related to the modeling of extreme sea levels, vulnerability functions, and the translation of flooding-induced damage to costs. This raises the following questions: what is the relative importance of each source of uncertainty in the final global-scale results? Which sources of uncertainty need to be considered? What uncertainties are of negligible influence? Hence, getting better insights in the role played by these uncertainties allows to ease their communication and to structure the message on future coastal impacts and induced losses. Using the integrated DIVA Model (see e.g. Hinkel et al., 2014, PNAS), we extensively explore the impact of these uncertainties in a global manner, i.e. by considering a large number (~3,000) of scenario combinations and by analyzing the associated results using a regression-based machine learning technique (i.e. regression decision trees). On this basis, we show the decreasing roles, over time, of the uncertainties in the extremes&#8217; modeling together with the increasing roles of SSP and of RCP after 2030 and 2080 for the damage and adaptation costs respectively. This means that mitigation of climate change helps to reduce uncertainty of adaptation costs, and choosing a particular SSP reduces the uncertainty on the expected damages. In addition, the tree structure of the machine learning technique allows an in-depth analysis of the interactions of the different uncertain factors. These results are discussed depending on the SLR data selected for the analysis, i.e. before and after the recently released IPCC SROCC report on September 2019.

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Unravelling the Importance of Uncertainties in Global-Scale Coastal Flood Risk Assessments under Sea Level Rise

Water ◽

10.3390/w13060774 ◽

2021 ◽

Vol 13 (6) ◽

pp. 774

Author(s):

Jeremy Rohmer ◽

Daniel Lincke ◽

Jochen Hinkel ◽

Gonéri Le Cozannet ◽

Erwin Lambert ◽

...

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Flood Risk ◽

Global Scale ◽

Short Term ◽

Sea Levels ◽

Coastal Flood ◽

Extreme Sea Levels ◽

Coastal Flood Risk ◽

Adaptation Costs

Global scale assessments of coastal flood damage and adaptation costs under 21st century sea-level rise are associated with a wide range of uncertainties, including those in future projections of socioeconomic development (shared socioeconomic pathways (SSP) scenarios), of greenhouse gas concentrations (RCP scenarios), and of sea-level rise at regional scale (RSLR), as well as structural uncertainties related to the modelling of extreme sea levels, data on exposed population and assets, and the costs of flood damages, etc. This raises the following questions: which sources of uncertainty need to be considered in such assessments and what is the relative importance of each source of uncertainty in the final results? Using the coastal flood module of the Dynamic Interactive Vulnerability Assessment modelling framework, we extensively explore the impact of scenario, data and model uncertainties in a global manner, i.e., by considering a large number (>2000) of simulation results. The influence of the uncertainties on the two risk metrics of expected annual damage (EAD), and adaptation costs (AC) related to coastal protection is assessed at global scale by combining variance-based sensitivity indices with a regression-based machine learning technique. On this basis, we show that the research priorities in terms of future data/knowledge acquisition to reduce uncertainty on EAD and AC differ depending on the considered time horizon. In the short term (before 2040), EAD uncertainty could be significantly decreased by 25 and 75% if the uncertainty of the translation of physical damage into costs and of the modelling of extreme sea levels could respectively be reduced. For AC, it is RSLR that primarily drives short-term uncertainty (with a contribution ~50%). In the longer term (>2050), uncertainty in EAD could be largely reduced by 75% if the SSP scenario could be unambiguously identified. For AC, it is the RCP selection that helps reducing uncertainty (up to 90% by the end of the century). Altogether, the uncertainty in future human activities (SSP and RCP) are the dominant source of the uncertainty in future coastal flood risk.

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Glacial Contributions to 21st Century Sea Level Rise

Eos ◽

10.1029/2020eo143700 ◽

2020 ◽

Vol 101 ◽

Author(s):

Kate Wheeling

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

21St Century ◽

Mass Change ◽

Sources Of Uncertainty

Researchers identify the main sources of uncertainty in projections of global glacier mass change, which is expected to add about 8–16 centimeters to sea level, through this century.

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Global LiDAR land elevation data reveal greatest sea-level rise vulnerability in the tropics

Nature Communications ◽

10.1038/s41467-021-23810-9 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

A. Hooijer ◽

R. Vernimmen

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Flood Risk ◽

Land Area ◽

Area At Risk ◽

Population Number ◽

Coastal Flood ◽

Elevation Data ◽

Coastal Flood Risk ◽

The Tropics

AbstractCoastal flood risk assessments require accurate land elevation data. Those to date existed only for limited parts of the world, which has resulted in high uncertainty in projections of land area at risk of sea-level rise (SLR). Here we have applied the first global elevation model derived from satellite LiDAR data. We find that of the worldwide land area less than 2 m above mean sea level, that is most vulnerable to SLR, 649,000 km2 or 62% is in the tropics. Even assuming a low-end relative SLR of 1 m by 2100 and a stable lowland population number and distribution, the 2020 population of 267 million on such land would increase to at least 410 million of which 72% in the tropics and 59% in tropical Asia alone. We conclude that the burden of current coastal flood risk and future SLR falls disproportionally on tropical regions, especially in Asia.

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Sea-level change in the Dutch Wadden Sea

Netherlands Journal of Geosciences – Geologie en Mijnbouw ◽

10.1017/njg.2018.7 ◽

2018 ◽

Vol 97 (3) ◽

pp. 79-127 ◽

Cited By ~ 10

Author(s):

Bert L.A. Vermeersen ◽

Aimée B.A. Slangen ◽

Theo Gerkema ◽

Fedor Baart ◽

Kim M. Cohen ◽

...

Keyword(s):

Climate Change ◽

Mass Loss ◽

Sea Level Rise ◽

Sea Level ◽

21St Century ◽

Wadden Sea ◽

Recent Literature ◽

Ghg Emissions ◽

Sea Level Change ◽

Level Change

AbstractRising sea levels due to climate change can have severe consequences for coastal populations and ecosystems all around the world. Understanding and projecting sea-level rise is especially important for low-lying countries such as the Netherlands. It is of specific interest for vulnerable ecological and morphodynamic regions, such as the Wadden Sea UNESCO World Heritage region.Here we provide an overview of sea-level projections for the 21st century for the Wadden Sea region and a condensed review of the scientific data, understanding and uncertainties underpinning the projections. The sea-level projections are formulated in the framework of the geological history of the Wadden Sea region and are based on the regional sea-level projections published in the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR5). These IPCC AR5 projections are compared against updates derived from more recent literature and evaluated for the Wadden Sea region. The projections are further put into perspective by including interannual variability based on long-term tide-gauge records from observing stations at Den Helder and Delfzijl.We consider three climate scenarios, following the Representative Concentration Pathways (RCPs), as defined in IPCC AR5: the RCP2.6 scenario assumes that greenhouse gas (GHG) emissions decline after 2020; the RCP4.5 scenario assumes that GHG emissions peak at 2040 and decline thereafter; and the RCP8.5 scenario represents a continued rise of GHG emissions throughout the 21st century. For RCP8.5, we also evaluate several scenarios from recent literature where the mass loss in Antarctica accelerates at rates exceeding those presented in IPCC AR5.For the Dutch Wadden Sea, the IPCC AR5-based projected sea-level rise is 0.07±0.06m for the RCP4.5 scenario for the period 2018–30 (uncertainties representing 5–95%), with the RCP2.6 and RCP8.5 scenarios projecting 0.01m less and more, respectively. The projected rates of sea-level change in 2030 range between 2.6mma−1for the 5th percentile of the RCP2.6 scenario to 9.1mma−1for the 95th percentile of the RCP8.5 scenario. For the period 2018–50, the differences between the scenarios increase, with projected changes of 0.16±0.12m for RCP2.6, 0.19±0.11m for RCP4.5 and 0.23±0.12m for RCP8.5. The accompanying rates of change range between 2.3 and 12.4mma−1in 2050. The differences between the scenarios amplify for the 2018–2100 period, with projected total changes of 0.41±0.25m for RCP2.6, 0.52±0.27m for RCP4.5 and 0.76±0.36m for RCP8.5. The projections for the RCP8.5 scenario are larger than the high-end projections presented in the 2008 Delta Commission Report (0.74m for 1990–2100) when the differences in time period are considered. The sea-level change rates range from 2.2 to 18.3mma−1for the year 2100.We also assess the effect of accelerated ice mass loss on the sea-level projections under the RCP8.5 scenario, as recent literature suggests that there may be a larger contribution from Antarctica than presented in IPCC AR5 (potentially exceeding 1m in 2100). Changes in episodic extreme events, such as storm surges, and periodic (tidal) contributions on (sub-)daily timescales, have not been included in these sea-level projections. However, the potential impacts of these processes on sea-level change rates have been assessed in the report.

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Flood damage costs under the sea level rise with warming of 1.5 °C and 2 °C

Environmental Research Letters ◽

10.1088/1748-9326/aacc76 ◽

2018 ◽

Vol 13 (7) ◽

pp. 074014 ◽

Cited By ~ 29

Author(s):

S Jevrejeva ◽

L P Jackson ◽

A Grinsted ◽

D Lincke ◽

B Marzeion

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Flood Damage ◽

Damage Costs

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EARLIEST DETECTION OF SEA-LEVEL RISE ACCELERATIONS TO INFORM UPGRADE/REPLACEMENT OF COASTAL FLOOD DEFENSE INFRASTRUCTURE

Coastal Sediments 2019 ◽

10.1142/9789811204487_0125 ◽

2019 ◽

Author(s):

ROBERT J. NICHOLLS ◽

IVAN D. HAIGH ◽

HAGEN RADTKE ◽

FRANCISCO CALAFAT ◽

PAOLO CIPOLLINI ◽

...

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Coastal Flood ◽

Flood Defense

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Coastal flooding in the Balearic Islands during the 21st century caused by sea level rise and extreme events

10.5194/egusphere-egu2020-4549 ◽

2020 ◽

Author(s):

Pau Luque Lozano ◽

Lluís Gómez-Pujol ◽

Marta Marcos ◽

Alejandro Orfila

Keyword(s):

Climate Change ◽

Sea Level Rise ◽

Sea Level ◽

21St Century ◽

Extreme Events ◽

Storm Surges ◽

Coastal Flooding ◽

Coastal Areas ◽

Balearic Islands ◽

Mean Sea Level

Sea-level rise induces a permanent loss of land with widespread ecological and economic impacts, most evident in urban and densely populated areas. The eventual coastline retreat combined with the action of waves and storm surges will end in more severe damages over coastal areas. These effects are expected to be particularly significant over islands, where coastal zones represent a relatively larger area vulnerable to marine hazards.Managing coastal flood risk at regional scales requires a prioritization of resources and socioeconomic activities along the coast. Stakeholders, such as regional authorities, coastal managers and private companies, need tools that help to address the evaluation of coastal risks and criteria to support decision-makers to clarify priorities and critical sites. For this reason, the regional Government of the Balearic Islands (Spain) in association with the Spanish Ministry of Agriculture, Fisheries and Environment has launched the Plan for Climate Change Coastal Adaptation. This framework integrates two levels of analysis. The first one relates with the identification of critical areas affected by coastal flooding and erosion under mean sea-level rise scenarios and the quantification of the extent of flooding, including marine extreme events. The second level assesses the impacts on infrastructures and assets from a socioeconomic perspective due to these hazards.In this context, this paper quantifies the effects of sea-level rise and marine extreme events caused by storm surges and waves along the coasts of the Balearic Islands (Western Mediterranean Sea) in terms of coastal flooding and potential erosion. Given the regional scale (~1500 km) of this study, the presented methodology adopts a compromise between accuracy, physical representativity and computational costs. We map the projected flooded coastal areas under two mean sea-level rise climate change scenarios, RCP4.5 and RCP8.5. To do so, we apply a corrected bathtub algorithm. Additionally, we compute the impact of extreme storm surges and waves using two 35-year hindcasts consistently forced by mean sea level pressure and surface winds from ERA-Interim reanalysis. Waves have been further propagated towards the nearshore to compute wave setup with higher accuracy. The 100-year return levels of joint storm surges and waves are used to map the spatial extent of flooding in more than 200 sandy beaches around the Balearic Islands by mid and late 21st century, using the hydrodynamical LISFLOOD-FP model and a high resolution (2 m) Digital Elevation Model.

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