Climate risks and adaptation in Asian coastal megacities: A synthesis

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events. The analysis undertaken in this report usesseveral methodologies that have long been usedin the context of disaster risk management—suchas damage cost assessment and probabilistic riskanalysis—illustrating the opportunities for crossfertilizationin both areas.Structure of the ReportChapter 2 presents methodologies used to determineclimate change risks at the city/river-basinlevel through downscaling techniques, flood riskassessment through hydrometeorological models,and damage cost analysis. Chapter 3 presentsthe main findings from climate downscaling,hydrological modeling analyses, and use of GISmapping. 10 Chapter 4 presents the analysis andfindings relating to damage cost assessment, aswell as an analysis of adaptation options. Finally,Chapter 5 draws broad policy lessons and presentsconclusions.10For a broader set of GIS maps, please refer to city-specificreports.4 | Climate Risks and Adaptation in Asian Coastal Megacities: A Synthesis Report
2Methodologies forDownscaling, HydrologicalMapping, and AssessingDamage CostsIn order to assess the impact of climate changein terms of increased flooding in 2050 in eachof the coastal cities, three main methodologicalsteps were taken. These include (1) determiningclimate-related impacts at the city/river-basin levelthrough downscaling; (2) developing flood riskassessment hydrometeorological models for eachcity to estimate flooding in 2050 under different scenarios;and (3) assessing damage costs. This chapterprovides a summary of these methodologies. Ithighlights the climate change scenarios selected, approachesto downscaling, assumptions underlyinghydrological analysis, and the approach to damagecost assessment. Some of the methodologies usedhere—such as damage cost analysis and probabilisticrisk assessment—are also used in disaster riskmanagement. 11 Uncertainties and errors involvedin different steps of the analysis are also discussed.Selection of EmissionsScenarios, Downscaling,and UncertaintiesTo measure the impact of climate change on thecities in 2050, it was necessary to assume emissionsscenarios and as a first step, “downscale” climatechange forecasts to local levels so that the meteorologicalparameters—such as changes in temperatureand precipitation—could be applied as inputs to thehydrometeorological models.Range of emissions scenarios consideredThe potential impact of climate change can varygreatly depending on the development pathwaythat is assumed. Beginning in 1992, the IPCC hasprovided various scenarios for the emissions ofgreenhouse gases based on assumptions of differentdevelopment pathways—namely, complex anddynamic interactions among future demographicchanges, economic growth, and technological and environmentalchanges. These emissions scenarios areprojections of what the future may look like and area tool to model climate change impacts and relateduncertainties. As described in the IPCC Special Report11A probabilistic risk assessment provides an estimateof the probability of loss due to hazards. It is commonlyused in disaster risk management planning and provides aquantitative baseline for measuring the benefits (or lossesavoided) of disaster management alternatives. In climatechange impact and adaptation studies, it also provides abaseline for assessing the change in risks due to the increasinghydrometeorological hazards associated withclimate change. See, for instance, Earthquake VulnerabilityReduction Program in Colombia, A Probabilistic Cost-benefitAnalysis (World Bank Policy Research Working Paper3939, June 2006) for an example of a probabilistic risk assessmentused in disaster risk management planning. Theprocess involves the development of several interconnectedmodules, which calculate in turn the hazard probability,exposure, vulnerability (or sensitivity to damage),damages, and losses. While the approaches used in the developmentof the modules and the calculation of the lossesvaried, each city case study did, however, follow a similaranalytical process.5
Page 4 and 5: © 2010 The International Bank for
Page 7 and 8: Figure 4.6 Damage Costs Associated
Page 9: AcknowledgmentsThis synthesis repor
Page 13 and 14: Executive SummaryIntroduction and R
Page 15 and 16: For each city, complex hydrometeoro
Page 17 and 18: infrastructure but a high emission
Page 19: these include strategies that focus
Page 23: policy implications have broader re
Page 28 and 29: Table 2.1 ■ Climate Change Foreca
Page 30 and 31: Return periods considered 18In this
Page 32 and 33: Figure 2.2 ■ Manila Rainfall-Runo
Page 34 and 35: Figure 2.3 ■ Estimation of Damage
Page 36 and 37: sion and distribution lines, and en
Page 38 and 39: Figure 2.5 ■ Possible Relationshi
Page 40 and 41: prices and the same prices are appl
Page 43 and 44: 3Estimating Flood Impactsand Vulner
Page 45 and 46: Table 3.2 ■ Bangkok Monthly Avera
Page 47 and 48: Estimation of storm surge in the ca
Page 49 and 50: Climate Change Impact and Adaptatio
Page 51 and 52: Figure 3.5a ■ Affected Condensed
Page 53 and 54: Manila’s current climate—Tropic
Page 55 and 56: Table 3.6 ■ Manila Climate Change
Page 57 and 58: Figure 3.10 ■ Areas of High Popul
Page 59 and 60: is also a key economic and financia
Page 61 and 62: Box 3.3 ■ HCMC in 2050Future land
Page 63 and 64: original swamp land on which the ci
Page 65 and 66: from 68 percent to 71 percent; that
Page 67 and 68: Table 3.15 ■ Districts Affected b
Page 69 and 70: Table 3.16 ■ Effects of Flooding
Page 71 and 72: 4Assessing Damage Costsand Prioriti
Page 73 and 74: Table 4.2 ■ Summary of Flood and
Page 75 and 76:
uilt outside the cities and are not
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■■■■■■For the eastern p
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Table 4.6 ■ Flood Damage Costs Wi
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Table 4.8 ■ Flood Damage Costs in
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Figure 4.5 ■ Loss Exceedance Curv
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Box 4.3 ■ Increased Time Costs an
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Table 4.11 ■ Adaptation Investmen
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Marikina River areas through a dam,
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Table 4.14 ■ Present Value of the
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of reducing vulnerability of the po
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5Conclusions andPolicy Implications
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open land use is expected to be flo
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hydrometeorological data, yielding
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BibliographyAllen, M. R., and W. J.
Page 103:
Reduction: Inventory and Prospect.
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a paper commissioned by JICA (Sugiy
Page 108 and 109:
mercial and industrial establishmen
Page 110 and 111:
ADB. The selection and prioritizati
Page 113 and 114:
AnnexCAdaptation to IncreasedFloodi
Page 115:
of people and institutions to manag
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THE WORLD BANK1818 H Street, NWWash
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Climate risks and adaptation in Asian coastal megacities: A synthesis

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