Future changes in extreme storm surges based on mega-ensemble projection using 60-km resolution atmospheric global circulation model

Mori, Nobuhito; Shimura, Tomoya; Yoshida, Kohei; Mizuta, Ryo; Okada, Y.; Fujita, Mikiko; Khujanazarov, Temur; Nakakita, Eiichi

doi:10.1080/21664250.2019.1586290

Cited by 66 publications

(45 citation statements)

References 34 publications

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“…The linear assumption is again applied to determine future extreme sea levels ( ESL F 100 ) by the linear addition of projected relative sea level rise ( RSLR ) by the end of 2100. This assumes that changes in wind speed and wave height over the coming century will be small, which is consistent with a number of recent studies 38 , 39 , 40 . SM 5 outlines the precedence for such linear superposition approaches for global-scale studies 4 , 7 , 8 , 9 , 10 , 11 and concludes that the potential errors are relatively small compared to the uncertainties in the extreme value analysis and RSLR projections.…”

Section: Discussionsupporting

confidence: 88%

Projections of global-scale extreme sea levels and resulting episodic coastal flooding over the 21st Century

Kirezci

Young

Ranasinghe

et al. 2020

Sci Rep

368

238

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Global models of tide, storm surge, and wave setup are used to obtain projections of episodic coastal flooding over the coming century. The models are extensively validated against tide gauge data and the impact of uncertainties and assumptions on projections estimated in detail. Global "hotspots" where there is projected to be a significant change in episodic flooding by the end of the century are identified and found to be mostly concentrated in north western Europe and Asia. Results show that for the case of, no coastal protection or adaptation, and a mean RCP8.5 scenario, there will be an increase of 48% of the world's land area, 52% of the global population and 46% of global assets at risk of flooding by 2100. A total of 68% of the global coastal area flooded will be caused by tide and storm events with 32% due to projected regional sea level rise. Sea level rise is a well-accepted consequence of climate change 1-3. Although the focus of the general public often tends to be on the rate and magnitude of increase in mean sea level, the major threats of coastal flooding and erosion are significantly impacted by episodic storm surge and wave setup (the temporary increase in mean water level due to the presence of breaking waves) as well as their time of occurrence in relation to astronomical tide 4. As approximately 600 million people live in low elevation coastal zones [i.e. LECZs-coastal regions less than 10 m above mean sea level (MSL)] which generate approximately US$1 trillion of global wealth 2,5-7 , both the environmental and socioeconomic impacts associated with episodic coastal flooding can be massive. Both national and global assessments of projected coastal flooding due to the combination of extreme events and sea level rise are critical in informing policy directions, as detailed in a number of IPCC reports. Such largescale assessments can also identify regional "hot-spots" where more detailed modelling is required. The time and space scales involved in such large-scale assessment are challenging. The time scales vary from the duration of individual storms (of order hours) to projections over the coming century (of order decades). The physical scales are also demanding, varying from the bathymetry of individual beaches (10s of m) to basin-scale storms to global comparisons of potential impacts (1000s of km). As a result, to form tractable solutions and guide such policy development, a variety of simplifying assumptions must be made. This study aims to undertake such an analysis. It assembles extensive model and measured datasets at coastlines around the world and combines these to provide projections of global extreme sea level and coastal flooding by 2100. The required simplifications may result in local errors but comparisons with recorded tide gauge data indicates that, to first-order, the simplified model adopted reproduces extreme sea levels to reasonable accuracy at national and global-scale. The Discussion

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Section: Discussionsupporting

confidence: 88%

Projections of global-scale extreme sea levels and resulting episodic coastal flooding over the 21st Century

Kirezci

Young

Ranasinghe

et al. 2020

Sci Rep

368

238

View full text Add to dashboard Cite

show abstract

“…Future storms are expected to become more intense while average (or mean) wave conditions are also expected to be modified by climate change [17][18][19] . Storm surge intensity and frequency are both expected to change in future 6,17,20 , while riverflows are expected to change by up to 40% in some regions 21 . These climate change driven variations in natural forcing are likely to result in significant morphological impacts along, especially, the sandy coastlines of the world 3,5,22,23 , which constitute 31% of the global coastline 24 and are subject to a very high level of human utilisation 2,25 .…”

Section: Climate Change Driven Coastal Changementioning

confidence: 99%

On the need for a new generation of coastal change models for the 21st century

Ranasinghe

2020

Sci Rep

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The combination of climate change impacts, declining fluvial sediment supply, and heavy human utilization of the coastal zone, arguably the most populated and developed land zone in the world, will very likely lead to massive socioeconomic and environmental losses in the coming decades. Effective coastal planning/management strategies that can help circumvent such losses require reliable local scale (<~10 km) projections of coastal change resulting from the integrated effect of climate change driven variations in mean sea level, storm surge, waves, and riverflows. Presently available numerical models are unable to adequately fulfill this need. A new generation of multi-scale, probabilistic coastal change models is urgently needed to comprehensively assess and optimise coastal risk at local scale, enabling risk informed, climate proof adaptation measures that strike a good balance between risk and reward. With approximately 10% of the global population living in the coastal zone 1 , the potentially massive impact of climate change on the world's coastal zones is now well recognized 2-6. Moreover, continued human attraction to the coast has resulted in rapid expansions in settlements, urbanization, infrastructure, economic activities and tourism, as exemplified by 15 of the world's 20 megacities being located in the coastal zone 7. The combination of climate change impacts, declining fluvial sediment supply 8,9 , and the ever increasing human utilization of the coastal zone is very likely to result in unprecedented socioeconomic and environmental losses in the coming decades 10-15. For example, the economic losses due to flooding alone in coastal cities is expected to be around US $ 1 Trillion by 2050 16. Similarly, the cost of forced migration due to just sea level rise (SLR) driven coastal erosion over the 21 st century is also expected to be around US $ 1 Trillion 2. Effective coastal planning/management strategies that can help circumvent such losses through adaptation require reliable projections of coastal change. This perspective addresses the question of how we may obtain such projections using numerical modelling techniques.

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“…3 d, e, and f). This result implies that future change of SSH can be predicted by applying pattern scaling between SSH and radiative forcing (e.g., Mitchell 2003;Mori et al 2019). These results indicate that SST patterns and global warming scenarios would affect the typhoon characteristics in future conditions, which could accordingly change future maximum SSH and vulnerable area to storm surge.…”

Section: Target Area 1: the Korean Peninsula (D2)mentioning

confidence: 81%

Assessment of uncertainties in projecting future changes to extreme storm surge height depending on future SST and greenhouse gas concentration scenarios

et al. 2020

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We assess uncertainties in projecting future changes in extreme storm surge height (SSH) based on typhoon data extracted from ensemble experiment results with four sea surface temperature (SST) conditions and three global warming scenarios using a single atmospheric global climate model. In particular, this study focus on typhoons passing around the Korean Peninsula (KP) defined as the region of 32 to 40° N and 122 to 132° E. It is predicted the number of the typhoons affecting the KP will decrease by 4~73% while their strength will increase by 0.8~1.4% under the given future conditions. The locations of genesis and lysis of the typhoons are expected to be shifted towards the northwest and northeast for all ensemble experiment conditions, respectively. However, the extent of their change varies depending on the future SST and global warming conditions. Storm surge simulations were carried out by using predicted typhoon data as an external force. It is found that future SST patterns and climate warming scenarios affect future typhoon characteristics, which influences values of extreme SSH and locations of the vulnerable area to storm surge under the future climate conditions. In particular, the values of extreme SSH and the locations of the vulnerable area to storm surge appear to be strongly influenced by both pathway and frequency of intense typhoons.

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Future changes in extreme storm surges based on mega-ensemble projection using 60-km resolution atmospheric global circulation model

Abstract: Nakakita (2019) Future changes in extreme storm surges based on mega-ensemble projection using 60-km resolution atmospheric global circulation model,

Cited by 66 publications

References 34 publications

Projections of global-scale extreme sea levels and resulting episodic coastal flooding over the 21st Century

Projections of global-scale extreme sea levels and resulting episodic coastal flooding over the 21st Century

On the need for a new generation of coastal change models for the 21st century

Assessment of uncertainties in projecting future changes to extreme storm surge height depending on future SST and greenhouse gas concentration scenarios

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