ESTIMATING GLOBAL SEA LEVEL VARIATIONS AND RESULTING INUNDATION EXPOSURE

Concerns about climate change highlights the needs to understand extreme sea levels and the resulting flood exposure in coastal areas on a global scale. The combined impacts of storm surge, tide, breaking wave setup and potential sea level rise will pose many economic, societal and engineering challenges in coming years. In order to predict the global coastal flood risk, a global sea level dataset of sufficiently long duration is required to undertake extreme value analysis. This presentation will outline the development and application of such a dataset.

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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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A global analysis of subsidence, relative sea-level change and coastal flood exposure

10.5194/egusphere-egu21-14985 ◽

2021 ◽

Author(s):

Daniel Lincke ◽

Robert J. Nicholls ◽

Jochen Hinkel ◽

Sally Brown ◽

Athanasios T. Vafeidis ◽

...

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Global Analysis ◽

Relative Sea Level ◽

Sea Levels ◽

Coastal Flood ◽

Global Issue ◽

Flood Exposure ◽

Relative Sea Level Rise ◽

Global Sea Level

Climate-induced sea-level rise and vertical land movements, including natural and human-induced subsidence in sedimentary coastal lowlands, combine to change relative sea levels around the world's coast. Global-average coastal relative sea-level rise was 2.5 mm/yr over the last two decades. However, as coastal inhabitants are preferentially located in subsiding locations, they experience an average relative sea-level rise up to four times faster at 7.8 to 9.9 mm/yr. This first global quantification of relative sea-level rise shows that the resulting impacts, and adaptation needs are much higher than reported global sea-level rise measurements would suggest. Hence, coastal subsidence is an important global issue that needs more assessment and action. In particular, human-induced subsidence in and surrounding coastal cities can be rapidly reduced with appropriate policy measures for groundwater utilization and drainage. This offers substantial and rapid benefits in terms of reducing growth of coastal flood exposure due to relative sea-level rise.

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Extreme sea levels along coastal China: uncertainties and implications

Stochastic Environmental Research and Risk Assessment ◽

10.1007/s00477-020-01964-0 ◽

2021 ◽

Author(s):

Jiayi Fang ◽

Thomas Wahl ◽

Qiang Zhang ◽

Sanne Muis ◽

Pan Hu ◽

...

Keyword(s):

Sea Level ◽

Storm Surge ◽

Hydrodynamic Model ◽

River Mouth ◽

Extreme Value Analysis ◽

Probability Curve ◽

Value Analysis ◽

Sea Levels ◽

Extreme Sea Levels ◽

Coastal China

AbstractExtreme sea levels (ESLs) due to typhoon-induced storm surge threaten the societal security of densely populated coastal China. Uncertainty in extreme value analysis (EVA) for ESL estimation has large implications for coastal communities’ adaptation to natural hazards. Here we evaluate uncertainties in ESL estimation and relevant driving factors based on hourly observations from 13 tide gauge stations and a complementary dataset derived from a hydrodynamic model. Results indicate significant uncertainties in ESL estimations stemming from using different EVA methods, which then propagate to the inundation assessment. Amplification factors due to sea-level rise (SLR) are highly sensitive to local relative SLR and the shape of the exceedance probability curve, which in turn depends on the selected EVA method. The hydrodynamic model hindcast indicates that high ESLs mainly occurred in eastern coastal China due to typhoon-induced storm surge. Larger uncertainties in the modelled ESLs are found for the coasts of the Yangtze River Delta, and particularly in the river mouth region. Future research and adaptation planning should prioritize these regions given expected future rising sea level, compound flood events, and human-induced factors (e.g. subsidence). This study provides theoretical and practical references for adaptation to ESL-related hazards along coastal China, with implications for coastal regions worldwide.

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Incorporating historical information to improve extreme sea level estimates

10.5194/nhess-2021-406 ◽

2022 ◽

Author(s):

Leigh R. MacPherson ◽

Arne Arns ◽

Svenja Fischer ◽

Fernando J. Méndez ◽

Jürgen Jensen

Keyword(s):

Tide Gauge ◽

Extreme Value ◽

Extreme Value Analysis ◽

Coastal Protection ◽

Protection Measures ◽

Value Analysis ◽

Sea Levels ◽

Systematic Data ◽

Historical Information ◽

Coastal Flood Risk

Abstract. Extreme value analysis seeks to assign probabilities to events which deviate significantly from the mean and is thus widely employed in disciplines dealing with natural hazards. In terms of extreme sea levels (ESLs), these probabilities help to define coastal flood risk which guides the design of coastal protection measures. While tide gauge and other systematic records are typically used to estimate ESLs, combining systematic data with historical information has been shown to reduce uncertainties and better represent statistical outliers. This paper introduces a new method for the incorporation of historical information in extreme value analysis which outperforms other commonly used approaches. Monte-Carlo Simulations are used to evaluate a posterior distribution of historical and systematic ESLs based on the prior distribution of systematic data. This approach is applied at the German town of Travemünde, providing larger ESL estimates compared to those determined using systematic data only. We highlight a potential to underestimate ESLs at Travemünde when historical information is disregarded, due to a period of relatively low ESL activity for the duration of the systematic record.

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Determining Extreme Still Water Levels for Design and Planning Purposes Incorporating Sea Level Rise: Sydney, Australia

Atmosphere ◽

10.3390/atmos13010095 ◽

2022 ◽

Vol 13 (1) ◽

pp. 95

Author(s):

Phil J. Watson

Keyword(s):

Sea Level Rise ◽

Water Level ◽

Sea Level ◽

Tide Gauge ◽

Water Levels ◽

Extreme Value Analysis ◽

Tide Gauge Record ◽

Value Analysis ◽

Mean Sea Level ◽

The Impact

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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Global Increasing Trends in Annual Maximum Daily Precipitation

Journal of Climate ◽

10.1175/jcli-d-12-00502.1 ◽

2013 ◽

Vol 26 (11) ◽

pp. 3904-3918 ◽

Cited By ~ 486

Author(s):

Seth Westra ◽

Lisa V. Alexander ◽

Francis W. Zwiers

Keyword(s):

Surface Temperature ◽

Daily Precipitation ◽

Global Scale ◽

Extreme Value Analysis ◽

Trend Test ◽

Precipitation Data ◽

Annual Maximum ◽

Value Analysis ◽

Near Surface ◽

Increasing Trends

Abstract This study investigates the presence of trends in annual maximum daily precipitation time series obtained from a global dataset of 8326 high-quality land-based observing stations with more than 30 years of record over the period from 1900 to 2009. Two complementary statistical techniques were adopted to evaluate the possible nonstationary behavior of these precipitation data. The first was a Mann–Kendall nonparametric trend test, and it was used to evaluate the existence of monotonic trends. The second was a nonstationary generalized extreme value analysis, and it was used to determine the strength of association between the precipitation extremes and globally averaged near-surface temperature. The outcomes are that statistically significant increasing trends can be detected at the global scale, with close to two-thirds of stations showing increases. Furthermore, there is a statistically significant association with globally averaged near-surface temperature, with the median intensity of extreme precipitation changing in proportion with changes in global mean temperature at a rate of between 5.9% and 7.7% K−1, depending on the method of analysis. This ratio was robust irrespective of record length or time period considered and was not strongly biased by the uneven global coverage of precipitation data. Finally, there is a distinct meridional variation, with the greatest sensitivity occurring in the tropics and higher latitudes and the minima around 13°S and 11°N. The greatest uncertainty was near the equator because of the limited number of sufficiently long precipitation records, and there remains an urgent need to improve data collection in this region to better constrain future changes in tropical precipitation.

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Volume–area scaling parameterisation of Norwegian ice caps: A comparison of different approaches

The Holocene ◽

10.1177/0959683616652712 ◽

2016 ◽

Vol 27 (1) ◽

pp. 164-171 ◽

Cited By ~ 1

Author(s):

Tron Laumann ◽

Atle Nesje

Keyword(s):

Water Resources ◽

Sea Level Rise ◽

Sea Level ◽

Sea Level Change ◽

Global Scale ◽

Two Dimensional ◽

Ice Caps ◽

Level Change ◽

Global Sea Level ◽

Best Fit

Over the recent decades, glaciers have in general continued to lose mass, causing surface lowering, volume reduction and frontal retreat, thus contributing to global sea-level rise. When making assessments of present and future sea-level change and management of water resources in glaciated catchments, precise estimates of glacier volume are important. The glacier volume cannot be measured on every single glacier. Therefore, the global glacier volume must be estimated from models or scaling approaches. Volume–area scaling is mostly applied for estimating volumes of glaciers and ice caps on a regional and global scale by using a statistical–theoretical relationship between glacier volume ( V) and area ( A) ( V = cAγ) (for explanation of the parameters c and γ, see Eq. 1). In this paper, a two-dimensional (2D) glacier model has been applied on four Norwegian ice caps (Hardangerjøkulen, Nordre Folgefonna, Spørteggbreen and Vestre Svartisen) in order to obtain values for the volume–area relationship on ice caps. The curve obtained for valley glaciers gives the best fit to the smallest plateau glaciers when c = 0.027 km3−2 γ and γ = 1.375, and a slightly poorer fit when the glacier increases in size. For ice caps, c = 0.056 km3−2 γ and γ = 1.25 fit reasonably well for the largest, but yield less fit to the smaller.

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Trends and projections in ice sheet mass balance

10.5194/egusphere-egu2020-20660 ◽

2020 ◽

Author(s):

Andrew Shepherd ◽

Keyword(s):

Mass Balance ◽

Sea Level Rise ◽

Sea Level ◽

Ice Sheets ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Ice Dynamics ◽

Surface Mass ◽

Sea Levels ◽

Global Sea Level

In recent decades, the Antarctic and Greenland Ice Sheets have been major contributors to global sea-level rise and are expected to be so in the future. Although increases in glacier flow and surface melting have been driven by oceanic and atmospheric warming, the degree and trajectory of today&#8217;s imbalance remain uncertain. Here we compare and combine 26 individual satellite records of changes in polar ice sheet volume, flow and gravitational potential to produce a reconciled estimate of their mass balance. Since the early 1990&#8217;s, ice losses from Antarctica and Greenland have caused global sea-levels to rise by 18.4 millimetres, on average, and there has been a sixfold increase in the volume of ice loss over time. Of this total, 41 % (7.6 millimetres) originates from Antarctica and 59 % (10.8 millimetres) is from Greenland. In this presentation, we compare our reconciled estimates of Antarctic and Greenland ice sheet mass change to IPCC projection of sea level rise to assess the model skill in predicting changes in ice dynamics and surface mass balance. &#160;Cumulative ice losses from both ice sheets have been close to the IPCC&#8217;s predicted rates for their high-end climate warming scenario, which forecast an additional 170 millimetres of global sea-level rise by 2100 when compared to their central estimate.

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Delta Deposits on Mars: A Global Perspective

10.5194/egusphere-egu21-5971 ◽

2021 ◽

Author(s):

Barbara De Toffoli ◽

Ana-Catalina Plesa ◽

Ernst Hauber ◽

Doris Breuer

Keyword(s):

Sea Level ◽

Large Scale ◽

Global Scale ◽

Channel Length ◽

Global Perspective ◽

Martian Surface ◽

Environmental Implications ◽

Complete Mapping ◽

Level Elevation ◽

Global Sea Level

The presence of delta deposits on Mars has been thoroughly demonstrated for decades and large scale mapping [1,2] highlighted the presence of several delta fans mainly located on the dichotomy boundary. While a previous delta inventory was compiled by Morgan et al. [3], we aim to update and finalize a complete mapping of delta deposits in order to allow the examination of the evolution and distribution of standing bodies of water on Mars. The objective of our project focuses on the production of a global catalogue of water-related features at the Martian surface, which are commonly studied separately or at smaller scales.Globally, we located around 150 deltas among which many were not previously included in published literature [e.g. 1,2,4]. We then examined the deltas based on two main traits. Firstly, we measured the length of the feeding channels since it may be (i) a proxy for the duration of the aqueous activity in the channel-delta system, and (ii) proportional to the age of the delta [2]. The latter relationship links older deltas near Chryse Planitia (>3 Ga) to longer valleys, while younger deltas are usually fed by shorter valleys [2]. Secondly, we measured the elevation of the delta population and compared the obtained dataset with the hypothesized sea level elevation of -2540 &#177; 177 m firstly suggested by Di Achille and Hynek [1] for a northern ocean through the analysis of deltas.We observed that, if the relationship between feeding channel length and delta age found for a sub-group of the population [2] is applicable as a rule of thumb to all deltas, many of the deposits have the potential to be Hesperian or Amazonian in age. They would thus be younger than the ocean that might have occupied the northern lowlands during the Noachian-Hesperian boundary period [1] and thus be unrelated to a global sea level range. In fact, less than half of the delta population is related to medium/long feeding channels (>30 km). Abundant pristine morphologies, both related to channels and deltas, also supports the hypothesis that part of the population is younger than Noachian. Additionally, the large variety of elevations where the deltaic deposits can be found and the very small amount of deltas included in the sea level elevation range proposed by Di Achille and Hynek [1] raise questions about the generation and environmental implications of these features, especially when seen at global scale.&#160;[1] Di Achille, G. & Hynek, B. M., Nat. Geosci. 3, 459&#8211;463 (2010).[2] Hauber, E. et al., J. Geophys. Res. E Planets 118, 1529&#8211;1544 (2013).[3] Morgan, A. M., et al., Lunar Planet. Sci. Conf. (2018).[4] Ori, G.G. et al., J. Geophys. Res. E Planets 105, 17629&#8211;17641 (2000).

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Sea level under climate change: Understanding the links between the past and the future

Climanosco Research Articles - https://www.climanosco.org/collection/climate-change-and-its-impacts/ ◽

10.37207/cra.2.6 ◽

2021 ◽

Author(s):

Keven Roy ◽

Nicole S. Khan ◽

Timothy A. Shaw ◽

Robert E. Kopp ◽

Benjamin P. Horton

Keyword(s):

Climate Change ◽

Sea Level ◽

Water Volume ◽

Sea Levels ◽

Global Average ◽

Flood Risks ◽

The Past ◽

Recent Climate ◽

Global Sea Level ◽

Global And Local

Rising global sea level, a consequence of climate change, results from an increase in the world ocean’s water volume and mass. Recent climate warming is responsible for producing the highest rate of global average sea-level rise of the past few millennia, and this rate will accelerate through the 21st century and beyond, exposing low-lying islands and coastal regions to significant flood risks. The flood risks can be compounded or diminished locally because changes in sea level are not uniform. In this review, we briefly discuss ice sheets as drivers of global and local sea levels, and how they could evolve under modern climate change. We underline some of the impacts of sea level change on coastal communities, and emphasize that local sea-level projections can be very different from estimates of the global average.

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