Cities, Seas, and StormsManaging Change in Pacific Island

Economies

Volume IVAdapting to Climate Change

November 30, 2000

in collaboration withPAPUA NEW GUINEA AND PACIFIC ISLANDS COUNTRY UNIT • THE WORLD BANK

· I·G·C·I· SPREP PICCAPEnvironment and

ConservationDivisionKiribati

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Administrator27449

Copyright © 2000The International Bank for ReconstructionAnd Development/ THE WORLD BANK1818 H Street, N.W.Washington, D.C. 20433, U.S.A.

All rights reservedManufactured in the United States of AmericaFirst printing November 13, 2000Second printing November 30, 2000

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Cities, Sea, and StormsManaging Change in Pacific Island Economies

Volume IVAdapting to Climate Change

November 30, 2000

PAPUA NEW GUINEA AND PACIFIC ISLAND COUNTRY UNITTHE WORLD BANK

ii

iii

Table of Contents

Page No.

Acknowledgements. vAcronyms and Abbreviations. vii

Executive Summary…………………………………………………………………….. ix

Chapter1. Key Challenges 1

Chapter 2. Climate Change Scenarios in the Pacific. 5

Chapter 3. Impact of Climate Change on a High Island: Viti Levu, Fiji. 7

A. Impact on Coastal Areas.. 8B. Impact on Water Resources. 11C. Impact on Agriculture....... 13D. Impact on Public Health 15

Chapter 4. Impact of Climate Change on Low Islands: Tarawa Atoll, Kiribati.. 19

A. Impact on Coastal Areas... 21B. Impact on Water Resources.. 23C. Impact on Agriculture... 25D. Impact on Public Health .. 25

Chapter 5. Impact of Climate Change to Regional Tuna Fisheries.. 27

Chapter 6. Toward Adaptation: Moderating the Effects of Climate Change 29

A. The Need for Immediate Action... 29B. Guidelines for Selecting Adaptation Measures. 30C. Adaptation Options .... 31D. Implementing Adaptation 34E. Funding Adaptation .. 36

Chapter 7. Summary of Key Findings and Recommendations... 39

References

Annex A. Assumptions Used in the Assessment of Climate Change Impacts

Map

iv

v

AcknowledgmentsVolume IV of this report was prepared by a team managed by Sofia Bettencourt (World Bank)

and Richard Warrick (IGCI). The report was the product of a partnership between the World Bank andthe International Global Change Institute (IGCI), University of Waikato, New Zealand, the Pacific IslandsClimate Change Assistance Programme (PICCAP) country teams of Fiji and Kiribati, the South PacificRegional Environment Programme (SPREP), Stratus Consulting Inc. (U.S.), the Center for InternationalClimate and Environmental Research (CICERO, Norway), and experts from numerous other institutionswho participated in the research. Background studies to this report are included in References.

The analysis of climate change impacts in Viti Levu, Fiji, was conducted by Jone Feresi (maineditor, Ministry of Agriculture, Fisheries and Forestry, Fiji), Gavin Kenny (coordinator and agricultureimpacts, IGCI), Neil de Wet (health impacts, IGCI), Leone Limalevu (coastal impacts, PICCAP nationalcoordinator), Jagat Bhusan (agriculture impacts, Ministry of Land and Mineral Resources), InokeRatukalou (agriculture impacts, Ministry of Agriculture, Fisheries and Forestry), Russell Maharaj (coastalimpacts, South Pacific Applied Geoscience Commission, SOPAC), Paul Kench (coastal impacts, IGCI),James Terry (water resources impact, University of South Pacific), Richard Ogoshi (agriculture impacts,University of Hawaii), and Simon Hales (health impacts, University of Otago, New Zealand).

The analysis of climate change impacts in Tarawa, Kiribati was conducted by Tianuare Taeuea(main editor and health impacts, Ministry of Health and Family Planning, Kiribati), Ioane Ubaitoi(agriculture impacts, Ministry of Agriculture), Nakibae Teutabo (agriculture, PICCAP nationalcoordinator at the Ministry of Environment and Social Development), Neil de Wet (health impacts,IGCI), Gavin Kenny (agriculture impacts, IGCI), Paul Kench (coastal impacts, IGCI), Tony Falkland(water impacts, Ecowise Environmental, Australia), and Simon Hales (health impacts, University ofOtago).

The analysis of climate change impacts on tuna fisheries was led by Patrick Lehodey and PeterWilliams (Secretariat of Pacific Community). John Campbell (IGCI) summarized the results of the studyand contributed to the review of adaptation strategies and climate variability impacts. Richard Jones andPeter Whetton (CSIRO, Australia) helped develop the scenarios for climate variability. W. Mitchellcontributed to the analysis of sea level rise.

The economic analysis of climate change impacts was carried out by Bob Raucher (StratusConsulting), Sofia Bettencourt, Vivek Suri (World Bank), and Asbjorn Aaheim and Linda Sygnes(CICERO). Wayne King (SPREP) contributed a regional overview, and Maarten van Aalst provided aninternational perspective and reviewed the final work. Samuel Fankhauser (European Bank forReconstruction and Development) and Mahesh Sharma (World Bank) provided advice on the design ofthe study and reviewed the draft results. Joel Smith (Stratus) contributed to the adaptation analysis. Theauthors are also grateful to Graham Sem and Gerald Miles (SPREP), Alf Simpson and Russell Howorth(SOPAC), Alipata Waqaicelua (Fiji Meteorological Services), Robin Broadfield and Noreen Beg (WorldBank), Herman Cesar (Free University of Amsterdam), Clive Wilkinson (Australian Institute of MarineSciences), and Ove Hoegh-Guldberg (University of Queensland) for their advice and support.

This volume is part of a four-volume Regional Economic Report prepared by Laurence Dunn,Stuart Whitehead, Sofia Bettencourt, Bruce Harris, Anthony Hughes, Vivek Suri, John Virdin, CeciliaBelita, David Freestone, Philipp Müller, Gert Van Santen, and Cynthia Dharmajaya. Natalie Meyenn,Danielle Tronchet, Peter Osei and Maria MacDonald provided important advice and support. BarbaraKarni helped edit the report. Fatu Tauafiafi (SPREP) contributed the cover photo design and concept.

vi

Peer reviewers included Iosefa Maiava (Forum Secretariat), Sawenaca Siwatibau (ESCAP PacificOperations Center), and Hilarian Codippily, Robert Watson, Mary Judd, Charles Kenny, and RichardScheiner (World Bank).

This report was funded by the World Bank Country Management Unit of Papua New Guinea andPacific Islands, the Australian Trust Fund for the Pacific, the PICCAP program, the World Bank ClimateChange group, the Norwegian Trust Fund, the New Zealand Trust Fund, and the Danish Trust Fund forGlobal Overlay. Many of the authors also contributed their own time and efforts to the study, for whichthe World Bank is grateful.

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Acronyms and AbbreviationsA$ Australian Dollar

A2 High Climate Sensitivity 4.5o C Greenhouse Gas Emissions Scenario

ADB Asian Development Bank

B2 Mid Climate Sensitivity 2.5 o C Greenhouse Gas Emissions Scenario

CDM Clean Development Mechanism

CICERO Center for International Climate and Environmental Research

CIMSIN Container Inhabiting Mosquito Simulation Model

CSIRO Commonwealth Scientific and Industrial Research Organization

CSIRO9M2 9-Layer Global Circulation Model of Australias CommonwealthScientific and Industrial Research Organization (Mark 2 Version)

DENSIM (Mosquito Population) Density Simulation Model

DHF Dengue Hemorrhagic Fever

DKRZ Deutsche Klimarechenzentrum (German Climate Monitoring Center)

DSS Dengue Shock Syndrome

EACNI East Asia and Pacific Country Management Unit for Papua New Guineaand Pacific Islands (World Bank)

EASRD East Asia and Pacific Regional Development and Natural Resources Unit(World Bank)

EAPVP East Asia and Pacific Vice Presidency (World Bank)

ENB Earth Negotiations Bulletin

ENSO El Niño Southern Oscillation

ESCAP Economic and Social Commission for Asia and the Pacific

FAO Food and Agriculture Organization of the United Nations

F$ Fijian Dollar

FFD Fiji Fisheries Division

GEF Global Environmental Facility

GCM Global Circulation Model

GDP Gross Domestic Product

GHG Greenhouse Gases

IGCI International Global Change Institute

IPCC Intergovernmental Panel on Climate Change

JICA Japan International Cooperation Agency

viii

M3 Cubic Meter

MAGICC Model for the Assessment of Greenhouse Gas Induced Climate Change

MHWS Mean High Water Spring (Level)

MSL Mean Sea Level

MT Metric Ton

NGOs Nongovernmental Organizations

PACCLIM Pacific Climate Change Impacts Model

PICCAP Pacific Islands Climate Change Assistance Programme

PLANTGRO Plant Growth Model from the Commonwealth Scientific and IndustrialResearch Organization

PNG Papua New Guinea

SEPODYM Spatial Environmental Population Dynamics Model

SLR Sea Level Rise

SOPAC South Pacific Applied Geoscience Commission

SPC Secretariat of the Pacific Community

SPCZ South Pacific Convergence Zone

SPECTRUM Population Growth Model from Spectrum Human Resources SystemsCorporation

SPREP South Pacific Regional Environmental Programme

SRES Special Report on Emission Scenarios

STM Shoreline Translation Model

SUTRA Saturated and Unsaturated Transport Model

UNDAC United Nations Disaster Assessment and Coordination

UNDP United Nations Development Programme

UNESCO United Nations Educational, Scientific and Cultural Organization

UNFCCC United Nations Framework Convention on Climate Change

US$ United States Dollar

US United States

WHO World Health Organization

WPWP Western Pacific Warm Pool

WRI World Resources Institute

Vice-President: Jemal-ud-din Kassum, EAPVPCountry Director: Klaus Rohland, EACNFActing Sector Director: Mark Wilson, EASRD

Task Team Leader: Laurence Dunn, EACNF

ix

Executive Summary

As the 21st century begins, the Pacific Islandpeople confront a future that will differdrastically from the past. Their physical climate,access to resources, ways of life, externalrelations and economic structures areundergoing simultaneous and interactive change.Pacific Island countries can actively engage inforeseeing and managing the process ofadaptation to these changes, or they can haveunplanned adaptation imposed on them byforces outside their control.

Managing these forces will be particularlycritical in the area of climate change, a subjectthat is very difficult for communities andgovernments to grasp, but of immense andimmediate impact on Pacific Island countries.Choosing a development path that decreases theislands vulnerability to climate events andmaintains the quality of the social and physicalenvironment will not only be central to thefuture well being of the Pacific Island people,but will also be a key factor in the countriesability to attract foreign investment in anincreasingly competitive global economy.

This volume examines the possible impacts ofchanges in climate on high and low islands ofthe Pacific, and discusses key adaptation andfinancing strategies available to Pacific Islandcountries. The short-term outcome of the reportis intended to be an improved understanding ofthe need and scope for adaptation policies inface of the challenges posed by climate change.Over the long term, it is hoped that the reportcan assist Pacific Island governments,businesses and communities to better adapt tochange by building on the strengths unique totheir countries and their people. It is also hopedthat the findings of the report can contribute tothe on-going international dialogue onadaptation financing.

This volume is divided into seven chapters.Chapter 1 outlines the nature of the challengesposed by climate change. Chapter 2 describesclimate change scenarios for the Pacific Island

region. Chapter 3 examines the physical andeconomic impact of these scenarios on a highisland of the Pacific Viti Levu, in Fiji. Thepotential impacts of climate change on coastalareas, water resources, agriculture, and healthare discussed in turn. Chapter 4 examines thepotential effect of climate change on a group oflow islands the Tarawa atoll in Kiribati focusing primarily on coastal and water resourceimpacts. Chapter 5 discusses the potentialimpact of climate change on the tuna fisheries ofthe Central and Western Pacific. Chapter 6proposes a general adaptation strategy forPacific Island countries. Key findings andrecommendations are summarized on Chapter 7.Annex A describes the methodology andassumptions used to assess climate changeimpacts. Detailed background studies to thisreport are included in References.

This volume is the last of a four-volume reportentitled Cities, Seas and Storms: ManagingChange in Pacific Island Economies producedby the World Bank as the Year 2000 RegionalEconomic Report for the Pacific Islands. Inaddition to this specialized volume, the seriesincludes a summary report (Volume I), a volumededicated to the management of Pacific towns(Volume II), and a volume dedicated to themanagement of the ocean (Volume III).

Impacts from Climate Change

The warming of the earths atmosphere is likelyto have substantial and widespread impacts onPacific Island economies, affecting sectors asvaried as health, coastal infrastructure, waterresources, agriculture, forestry and fisheries.

Some policymakers dismiss the impacts ofclimate change as a problem of the future. Butthere is evidence that similar impacts are alreadybeing felt: the Pacific Islands are becomingincreasingly vulnerable to extreme weatherevents as growing urbanization and squatter

x

settlements, degradation of coastal ecosystems,and rapidly developing infrastructure on coastalareas intensify the islands natural exposure toclimate events.

According to climate change models, the sealevel may rise by 23─43 centimeters and theaverage temperature by 0.901.30C by 2050.Among the most substantial impacts of climatechange would be losses of coastal infrastructureand land resulting from inundation, storm surge,and shoreline erosion. Climate change could alsocause more intense cyclones and droughts, thefailure of subsistence crops and coastal fisheries,losses in coral reefs, and the spread of malariaand dengue fever.

In the absence of adaptation, a high island suchas Viti Levu could experience average annualeconomic losses (in 1998 dollars) ofUS$23─$52 million by 2050, equivalent to 2─4percent of Fijis GDP. A low group of islandssuch as the Tarawa atoll in Kiribati could faceaverage annual damages of US$8─$16 millionby 2050, as compared to a current GDP ofUS$47 million. These costs could beconsiderably higher in years of extreme weatherevents such as cyclones, droughts and largestorm surges.

How certain is climate change? A soon to bereleased review by the Intergovernmental Panelon Climate Change (IPCC) concludes thatmankind has contributed substantially toobserved warming over the last 50 years. Whilethere is growing consensus that climate changeis occurring, uncertainties remain on the timingand magnitude of the changes. Most studies,however, consider the Pacific Islands to be athigh risk from climate change and sea level rise.

A Strategy for AdaptationHow should Pacific Island countries adapt toclimate change? One possibility is to donothing, and by implication hope that climatechange does not happen. This is the de factopresent position of many governments, includingthose of several Pacific Island countries.

Another possibility might be to assume theworst and embark upon major investments incoastal protection such as seawalls andrelocation of vulnerable infrastructure. The firstapproach is unwise in light of the increasingevidence of climate change. The second isimpractical and unaffordable.

This report recommends that Pacific Islandcountries follow a strategy of precautionaryadaptation. Since it is difficult to predict far inadvance how climate change will affect aparticular site, Pacific Island countries shouldavoid adaptation measures that could fail or haveunanticipated social or economic consequencesif climate change impacts turned out to bedifferent than anticipated (IPCC 1998). As afirst step, it is recommended that Pacific Islandscountries adopt no regrets adaptationmeasures that would be justified even in theabsence of climate change. These include bettermanagement of natural resourcesparticularlyof coastal habitats, land, and waterandmeasures such as disease vector control andimproved spatial planning.

Acting now to reduce vulnerability to extremeweather events would go a long way towardpreparing Pacific countries for the future, andreducing the magnitude of the damage. Takingearly action may require adjustments ofdevelopment paths and the sacrifice of someshort-term economic gains. But it would vastlydecrease the downsize costs should climatechange scenarios materialize. The challengewill be to find an acceptable level of risk─anintermediate solution between a policy ofinaction and investing in high costsolutions─and start adapting long before theexpected impacts occur.

Under a no regrets adaptation policy, PacificIsland governments would take adaptation goalsinto account in future expenditure planning,would support community-based adaptation, andwould require major infrastructure investmentsto meet adaptation criteria. Adaptation would beviewed as a key feature in national policy in itsown right, and would be taken into account inthe development of policies in a wide range ofsectors and activities.

xi

The question of who will fund adaptation is adifficult and sensitive issue. Insofar as noregrets measures help reduce the islandsvulnerability to current climate events(independently of climate change) Pacific Islandgovernments would be justified in fundingadaptation from reallocations in publicexpenditures and development aid. Donorscould support this process directly, or as part ofnatural resources and environmentalmanagement assistance.

The analysis of this report, however, clearlyshows that the Pacific Islands are likely toexperience significant incremental costsassociated with climate change. It is urgent thatthe international community develop financingmechanisms to help countries in the receivingend of climate change to fund no regretsadaptation. Countries that have taken early

action using their own resources should not bepenalized with lower future allocations. Theseand other disincentives against no regretspolicies need to be urgently discussed ininternational forums. Of paramount importance,however, will be for the internationalcommunity to move rapidly to develop afinancing mechanism to assist countries such asthe Pacific Islands in taking early adaptiveaction. The urgency of this action for smallisland states cannot be over-emphasized.

Although uncertainties remain, it now seemscertain that climate change will affect manyfacets of Pacific Island peoples lives in waysthat are only now beginning to be understood.As such, climate change must be considered oneof the most important challenges of the twenty-first century and a priority for immediate action.

1

Chapter 1 Key Challenges

Across the Pacific, atoll dwellers speak ofhaving to move their houses away from theocean because of coastal erosion; of having tochange cropping patterns because of saltwaterintrusion; of changes in wind, rainfall, and oceancurrents. While these events may simply reflectclimate variability, they illustrate the types ofimpacts likely to be felt under climate change.

Many policymakers dismiss climate change as aproblem of the future. But impacts similar tothose resulting from climate change are alreadybeing felt, as the Pacific Islands becomeincreasingly vulnerable to extreme weatherevents and to climate variability. Cyclones Ofaand Val, which hit Samoa in 199091, causedlosses of US$440 millionin excess of thecountrys annual gross domestic product (GDP).Fiji was hit by four cyclones, two droughts, andsevere flooding in the past eight years. In the1990s alone, the cost of extreme events in thePacific Island region exceeded US$1 billion(table 1).

Rising Vulnerability to ExtremeWeather Events

The impacts of extreme weather events arebecoming stronger as the islands vulnerabilityrises. Growing urbanization and squattersettlements, degradation of coastal ecosystems,and rapidly developing infrastructure on coastalareas are intensifying the islands exposure toextreme weather events. At the same time,traditional practices promoting adaptation, suchas multicrop agriculture, are graduallyweakening (box 2).

Box 1. Climate Change and Climate Variability

Climate change is the gradual warming of the earthsatmosphere caused by emissions of heat-absorbing greenhousegases, such as carbon dioxide and methane. The term isgenerally used to reflect longer-term changes, such as higherair and sea temperatures and a rising sea level.

Climate variability reflects shorter-term extreme weatherevents, such as tropical cyclones and the El Niño SouthernOscillation (ENSO). While there is some evidence that climatevariability will increase as a result of climate change, manyuncertainties remain.

Mitigation and adaptation also have distinct meanings amongclimate change experts. Mitigation refers to efforts to reducegreenhouse gas emissions. Adaptation refers to efforts toprotect against climate change impacts.

Table 1. Estimated Costs of Extreme WeatherEvents in the Pacific Island Region during the 1990s

(millions of US$)

Event Year CountryEstimated

losses

Cyclone Ofa 1990 Samoa 140Cyclone Val 1991 Samoa 300Typhoon Omar 1992 Guam 300Cyclone Nina 1993 Solomon Islands Cyclone Prema 1993 Vanuatu Cyclone Kina 1993 Fiji 140Cyclone Martin 1997 Cook Island 7.5Cyclone Hina 1997 Tonga 14.5Drought 1997 Regional > 175aCyclone Cora 1998 Tonga 56Cyclone Alan 1998 French

Polynesia

Cyclone Dani 1999 Fiji 3.5

Not available.a. Includes losses of US$160 million in Fiji.Note: Minor events and disasters in Papua New Guinea not included. Costs are not adjusted for inflation.Source: Campbell 1999, and background studies to this report.

2

Compounding Impacts ofClimate Change

Arriving on top of this increased vulnerability,climate change is only likely to exacerbate thecurrent impacts, whether or not climatevariability increases in the futureand there issome evidence that it may. In low islands, themost substantial damage would come fromlosses to coastal infrastructure as a result ofinundation, storm surge, or shoreline erosion.But climate change could also cause more

intense cyclones and droughts, the failure ofsubsistence crops and coastal fisheries, losses incoral reefs, and the spread of malaria and denguefever. These impacts could be felt soon: ifclimate change models are correct, the averagesea level could rise 1121 centimeters andaverage temperatures could rise 0.500.60C by2025.

The economic impact could be substantial.Estimates from this study indicate that if climate

The effect of Cyclone Melia on crops depended on the distancefrom the storm (see table on left). While at the storm centercrop damage was nearly 100 percent, at distances of 30-100kilometers from the storm, traditional crops such as taro andyam suffered much less damage than nontraditional crops suchas cassava.

Cassava is becoming increasingly prevalent in the Pacific as asubsistence crop because of its ability to grow on poor soils andthe low labor inputs required. But its low resilience to cyclonesincreases the likelihood that food rations will be required duringthe cyclone season. In most cases, the best strategy for foodsecurity in cyclone-prone areas is crop diversity and themaintenance of traditional crops.

If tropical cyclone intensity increases under climate change, itis likely that the trend toward cultivation of cassava will resultin greater food crop losses than would be the case if traditionalroot crops were maintained. From this perspective, promotingtraditional multicrop agriculture may also be the bestadaptation to climate change.

Tropical cyclones are regular occurrences inmany Pacific Islands. Traditional societiesadapted to these events by using a range ofresilient food crops and food preservationtechniques. Many communities used faminefoods during times of scarcity and followedtraditional obligations to provide for victims ofdisasters.

This resilience is diminishing, however, leavingmany Pacific Islands increasingly vulnerable toextreme weather events. An example is theincreasing use of nontraditional crops, such ascassava.

Cyclone Meli devastated much of the SouthernLau Island Group in Fiji in 1979 (see figure).Islands such as Nayau were subject to winds ofmore than 80 knots; other islands, such asOgea, experienced only gale force winds.

Distancefromstorm

(kilometers)

Percentage of rootcrops destroyed

Percentage of tree crops destroyed

Island Cassava Taro Yam Banana Coconut Breadfruit

Nayau 0 100100947560606050605050

1009655

80 100 100 100Cicia 30 54 100 91 100Lakeba 30 48 82 75 50Vanuavatu 45 75 60 50Oneata 67 10 50 40 40Komo 86 40 30 40Moce 88 10 50 40 40Namuka 99 50 15 30Kabara 99 10 50 40Fulaga 129 40 10 30Ogea 142 40 10 30

Source: Campbell (1995)

Box 2. Rising Vulnerability to Extreme Weather Events

3

change scenarios materialize, a high island suchas Viti Levu in Fiji could suffer economicdamages of more than US$23─$52 million ayear by 2050 (in 1998 dollars), equivalent to2─4 percent of Fijis gross domestic product(GDP). The Tarawa atoll in Kiribati could faceaverage annual economic damages ofUS$8─$16 million by 2050 (as compared with aGDP of about US$47 million). In years of strongstorm surge, up to 54 percent of South Tarawacould be inundated, with capital losses of up toUS$430 million.

Climate change would have the greatest impacton the poorest and most vulnerable segments ofthe populationthose most likely to live insquatter settlements exposed to storm surges anddisease (where safety nets have weakened), andthose most dependent on subsistence fisheriesand crops destroyed by cyclones and droughts.Nevertheless, the impacts of climate change arelikely to be pervasive and affect the lives ofmost Pacific Islanders.

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5

Chapter 2 Climate Change Scenarios in the Pacific

In 19992000 the World Bank helped sponsor astudy of vulnerability, adaptation, and economicimpact of climate change in the Pacific Islandregion.1 The analysis used an integrated modelof climate change developed for the region, thePacific Climate Change Impacts Model(PACCLIM), complemented by sectoral impactmodels, population projections, and baselinedata such as historical climate records. Based onthe best scientific information available for theregion, the following scenarios were used by thestudy (table 2):

• Rise in sea level. Sea level could rise 0.2meters (in the best-guess scenario) to 0.4meters (in the worst-case scenario) by 2050.By 2100, the sea could rise by 0.5-1.0meters relative to present levels. The impact

1 See Acknowledgments for a list of the experts andorganizations that participated in the study. Backgroundstudies to this report are cited in References. Theassumptions used by the study are detailed in Annex A.

would be critical for low-lying atolls in thePacific, which rarely rise 5 meters above sealevel. It could also have widespreadimplications for the estimated 90 percent ofPacific Islanders who live on or near thecoast (Kaluwin and Smith 1997).

• Increase in surface air temperature. Airtemperature could increase 0.90-1.30 C by2050 and 1.60-3.40C by 2100.2

• Changes in rainfall. Rainfall could eitherrise or fallmost models predict anincreaseby 8-10 percent in 2050 and byabout 20 percent in 2100, leading to moreintense floods or droughts.

2 A new report by the Intergovernmental Panel on ClimateChange, scheduled to be finalized in early 2001, raises theworst case scenario for surface air temperature to 6o C by2100. This means that if the worst case scenariomaterializes, the impacts may be considerably higher thanestimated here.

Impact 2025 2050 2100 Level of Certainty

Sea level rise (centimeters) 11─21 23─43 50─103 ModerateAir temperature increase (degrees Centigrade) Fiji 0.5─0.6 0.9─1.3 1.6─3.3 High Kiribati 0.5─0.6 0.9─1.3 1.6─3.4 HighChange in rainfall (percent) Fiji -3.7─+3.7 -8.2─+8.2 -20.3─+20.3 Low Kiribati -4.8─+3.2 -10.7─+7.1 -26.9─+17.7 LowCyclones

Frequency Models produce conflicting results Very Low Intensity (percentage increase in wind speed) 0─20 Moderate Region of formation No change Low Region of occurrence No change or increase to north and south LowEl Niño Southern Oscillation (ENSO) A more El Niñolike mean state Moderate

Note: Ranges given reflect a best-guess scenario (lower value) and a worst-case scenario (higher value). Sea level rise is derived from global projections, as regional models have not yet been developed. Temperature and rainfall projections are based on the CSIRO9M2 and the DKRZ Global Circulation Models. ENSO and cyclone scenarios are based on a comprehensive review of climate variability in the South Pacific (Jones and others 1999). For details, see Annex A.

Table 2. Climate Change and Variability Scenarios in the Pacific Island Region

6

• Increased frequency of El Niño-likeconditions. The balance of evidenceindicates that El Niño conditions may occurmore frequently, leading to higher averagerainfall in the central Pacific and northernPolynesia. The impact of El Niño SouthernOscillation (ENSO) on rainfall in Melanesia,Micronesia, and South Polynesia is less wellunderstood (Jones and others 1999).

• Increased intensity of cyclones. Cyclonesmay become more intense in the future (withwind speeds rising by as much as 20percent); it is unknown, however, whetherthey will become more frequent. A rise insea surface temperature and a shift to ElNiño conditions could expand the cyclonepath poleward, and expand cycloneoccurrence east of the dateline. Thecombination of more intense cyclones and ahigher sea level may also lead to higherstorm surges (Jones and others 1999).

How certain is climate change? TheIntergovernmental Panel on Climate Change(IPCC) stated in 1995 that the balance ofevidence suggests a discernible humaninfluence on global climate change (IPCC1995). In a report scheduled to be finalized inearly 2001, however, IPCC concluded thathuman influence had contributed substantially toobserved warming over the past 50 years.

While there is growing consensus among expertsthat climate change is occurring, uncertaintiesremain about the magnitude and timing of thechanges. For small island states, these

uncertainties are magnified because the area ofthe countries usually falls below the levels ofresolution of the general circulation modelsused.

Some changes are more certain than others:there is emerging consensus that global averagetemperature and sea levels will increase.Rainfall changes remain highly uncertain,however, as does the relationship between long-term climate change and extreme events.Uncertainties also increase with spatialresolution: there is greater confidence in modelprojections of global average changes than inprojections of regional or local level changes.Impacts on coastal areas and water resources aregenerally more certain than impacts onagriculture and health. And uncertaintyincreases with time: projections for 2100 are lesscertain than projections for 2050. Despite theseuncertainties, most studies consider the PacificIslands to be at high risk from climate changeand sea level rise (Kench and Cowell 1999).

Based on the results of the study, the physicaland economic impacts of climate change in thePacific Island region are illustrated here by theexample of a high islandViti Levu in Fijiand a group of low islandsthe Tarawa atoll inKiribati. To give perspective to the analysis, alleconomic damages were estimated for 2050 as ifthe impacts had occurred under todays socio-economic conditions. Ranges provided representa best guess scenario (the lower bound) and aworst case scenario (the upper bound). Alleconomic costs reflect 1998 US dollars, andassume no adaptation.

7

Chapter 3Impact of Climate Change on a High Island

Viti Levu, Fiji

With an area of 10,389 square kilometers, VitiLevu is the largest island in Fiji. Seventy-sevenpercent of Fijis population595,000 people in1996reside there. It is also in Viti Levu thatFijis major cities, industries, and tourismfacilities are located (box 3).

By 2050, under the climate change scenariosused by the study, Viti Levu could experienceannual economic losses of US$23$52 million(table 3). Because the losses are annualaverages, they dampen the potential impact ofextreme weather events, which could be

Box 3. Viti Levu (Fiji) at a Glance

*

Climate: Oceanic tropical• Average temperature: 23o ─27o C.• Average rainfall: East Viti Levu 3,000─5,000 milimeters. West V. Levu 2,000─3,000 milimeters.Major Influences• Southeast trade winds.• El Niño Southern Oscillation (ENSO).• South Pacific Convergence Zone.Extreme Events• Tropical cyclones.• Droughts (often associated with ENSO).Population• Population: 772,655 in 1996 (595,000 or 77% in Viti Levu).• Average annual growth rate: 0.8%.• 60% rural, but growing urbanization.Economy• GDP (1998): US$1,383 million.• Narrow base, with sugar and tourism dominating.• Average annual growth: 2.7% (199396).• Growth affected by tropical cyclones and drought.• Main exports: sugar, gold, garments.

Future Population Trends• Increasing population density, especially in urban areas,

coastal areas, flood plains, and marginal hill lands.Implications:• Denser urban structures.• Spread of urban areas to coastal margins and inland.• Increase in proportion of squatter housing.• Increase in coastal infrastructure (related to tourism).

Future Economic Trends• Continued dependence on natural resources.• Tourism sector likely to grow.• Agriculture will continue to be important in subsistence

production and as export earner. Role of sugar uncertaindue to future removal of subsidies and land tenure.Possible increase in traditional crops, such as kava.

• Growing importance of cash economy.• Continued dependence on foreign aid.

Future Environmental Trends

• Environmental degradation in densely populated areas(especially coastal and lowland) and in marginal farmland.

• Increase in deforestation.• Increase in problems of waste disposal (sewage, solid waste,

and chemical pollution).

Future Sociocultural Trends

• Reduction in importance of traditional kinship systems.• Increase in preference for imported foods.• Increase in noncommunicable diseases associated with

nutritional and lifestyle changes.• Increase in poverty and social problems in urban areas.

8

substantially higher in a particular year: anaverage cyclone could cause damages of morethan US$40 million, while a drought comparableto the 1997/98 event could cost Viti Levu someUS$70 million in lost crops.

Among the most significant incremental impactsof climate change would be damages toinfrastructure and ecosystems of coastal areas(averaging about US$8$20 million a year by2050). But a higher intensity of cyclones couldalso result in substantial damages, up to US$11million a year. Changes in rainfall could lead toagricultural losses of US$14 million per year,and the combined effect of higher temperaturesand stronger climate variability could result inpublic health costs of more than US$1$6million a year. These estimates assume no

adaptation and are subject to large margins ofuncertainty. But they probably underestimate thecosts of actual damages, as many impacts (suchas nutrition and loss of lives) could only beassessed qualitatively.

A. Impact on Coastal AreasViti Levus coastal areas are naturally exposedto weather events. About 86 percent of the 750-kilometer coast lies at elevations that are lessthan 5 meters from sea level. Intensive urbandevelopment, growing poverty, deforestation ofwatersheds, pollution, and increased exploitationof coastal resources have exposed large areas ofthe coast to erosion and inundation. Somevillages have reported shoreline retreats of 15

Table 3. Estimated Annual Economic Impact of Climate Change on Viti Levu, Fiji, 2050 (millions of 1998 US$)

Impact Annual damagea Level ofCertainty

Likelycost of an

extreme eventbExtreme

event

Impact on coastal areas Loss of coastal land and infrastructure to erosion 3-6 Moderate ─ ─ Loss of coastal land and infrastructure to inundation and storm surge 0.3-0.5 Moderate 75-90

LargeStorm Surge

Loss of coral reefs and related services 5-14 Very low ─ ─ Loss of nonmonetized services from coral reefs, mangroves and seagrasses + Very low ─ ─

Impact on water resources Increase in cyclone severity 011 Moderate 40 Cyclone Increase in intensity of droughts (related to El Niño) + Moderate 50-70 Drought Changes in annual rainfall (other than impacts on agriculture) + Low ─ ─

Impact on agriculture Loss of sugarcane, yams, taro, and cassava due to temperature or rainfall changes and ENSO 14 Moderate 70 Drought Loss of other crops + Very Low ─ ─

Impact on public health Increased incidence of dengue fever 1-6 Moderate 30 Large epidemic Increase in fatal dengue fever cases + Very Low ─ ─ Increased incidence of diarrhea 0-1 Low ─ ─ Infant mortality due to diarrhea + Very Low ─ ─ Impact of cyclones and droughts on public safety + Very Low ─ ─

Total estimated damages >23-52++ Likely to have economic costs, but impact not quantified. ─ Not available.a Reflects the incremental average annual costs of climate change. b Reflects the absolute (non-incremental) cost of a future extreme event.Numbers are rounded.Note: For assumptions, see annex A.Source: Background studies to this report.

9

20 meters over the past few decades due to lossof mangroves (Mimura and Nunn 1994).

Climate change is expected to affect the coast ofViti Levu through a rise in sea level (23─43centimeters by 2050), higher temperatures(0.9─1.3o C by 2050), and more intensecyclones, resulting in further coastal erosion andinundation as well as a decline in coral reefs(figure 4.1). The resulting economic losses areconservatively estimated at US$8─$20 million ayear by 2050.

To assess the potential impact of sea level riseon coastal erosion and inundation, four sectionsof Viti Levu were surveyed (see map, box 3):

• Suva Peninsula, representing major towns orabout 5 percent of Viti Levus coast.

• Korotogo on the southern coast, representingareas with major tourism settlements andcoastal villages (28 percent of the coast).

• Tuvu, on the northwest coast, with intensivesugarcane fields and mangroves(about 47 percent of the coast).

• Western Rewa River Delta,representing low-lyingmangrove and delta areas (10percent of the coast).

The erosion analysis did not includeSuva because the city is alreadyheavily protected by seawalls.

Coastal Erosion. The first-orderestimates of potential erosionindicate that, by 2050, Viti Levusshoreline could retreat by 1─3meters at Korotogo, 9─12 meters atTuvu, and 112─251 meters at theRewa river delta (table 4).Extrapolating these results to otherareas of Viti Levu is difficult due tothe variations in topography.Nevertheless, using estimates fromthe three sites surveyed,1,150─2,300 hectares of coastline (2to 4 percent of the land below 10meters altitude) could be lost by2050. By 2100, the proportion of

Table 4. Potential Shoreline Retreat in Viti Levu, FijiResulting from Sea Level Rise, 2025, 2050, and 2100

Impact 2025 2050 2100

Potential shoreline retreat (in meters) Korotogo (South coast) 1 1-3 4-9 Tuvu (Northwest coast) 7-9 9-12 13-29 Western Rewa river delta 50-112 112-251 319-646

Total land eroded (in hectares) Tourism areas (like Korotogo) 10-22 22-53 63-145 Sugarcane areas (like Tuvu) 188-253 253-323 362-818 Low-lying mangrove and delta (like Rewa) 390-875 875-1,955 2,485-5,036 Percentage coastal strip eroded (< 10 meters) 1-2 2-4 5-10 Total land eroded (in hectares) 588-1,150 1,150-2,331 2,910-6,000

Value of land lost to erosion (US$ million) Tourism areas (like Korotogo) 0.2-0.4 0.4-1.0 1.2-2.8 Sugarcane areas (like Tuvu) 4.3-5.8 5.8-7.3 8.2-18.6 Low-lying mangrove and delta (like Rewa) 8.9-19.9 19.9-44.5 56.5-114.5 Total capital value of land lost 13.3-26.1 26.1-52.8 66.0-136.0 Annualized lossesa 1.5-2.9 2.9-5.8 7.3-15.0

Notes: Ranges reflect best guess (lower value) and worst case scenarios (higher value). Land eroded and value of land lost are extrapolated from the sites surveyed, and cover about

85 percent of the Viti Levu coast.a. Reflects the annual value of the losses, or the capital recovery factor.

Source: Background studies to this report. For assumptions, see annex A.

Figure 1. Likely Impact of Climate Change on CoastalAreas in Viti Levu, Fiji

Sea LevelRise

Impacts onCoral Reefs

Increase waveEnergy

Reduce sedimentproduction

Increasedexposure

to inundation

Increasedcoastalerosion

IncreasedTropicalCycloneIntensity

IncreasedSea

Surface

ShorewardRetreat ofMangroves

IncreasedRiver

Flooding

10

land eroded could be as high as 10 percent.Based on current values of land, the annualizedeconomic damages due to climate change wouldbe in the order of US$2.9 to US$5.8 million ayear by 2050 (table 4). This is likely to be anunderestimate, as the sites surveyed wererepresentative of just about 85 percent of VitiLevus coast, and the Tuvu site under-representslow-lying sugarcane fields on the north shore.

Coastal Inundation. The analysis conducted inViti Levu indicates that sea level rise wouldresult in relatively modest levels of inundation ─affecting about 0.6 to 5.9 percent of coastal landbelow 10 meters altitude by 2050. However, inyears of strong storm surge ─ such as the 1 in 50year event shown on table 5 ─ Viti Levu couldexperience losses in capital assets of US$75-$90million, some US$15-$30 million higher thanwhat is experienced today (table 5).

Past research also suggests the following likelyimpacts of climate change (Solomon and Kruger1996):

• Overtopping of shore protection indowntown Suva during extreme waveimpacts (if sea level rises 25 centimeters).

• Serious flooding in large parts of Suva Pointand downtown Suva even during moderatetropical cyclones (if sea level rises 100centimeters).

• Raised water tables in low-lying areas.

• Reduced efficacy of in-ground septic andsewer pumping systems.

• Increased sedimentation of channels,shoreward retreat of mangroves, andincreased susceptibility to floods in theRewa Delta.

Mangroves and Coral Reefs. Viti Levu isestimated to have 23,500 hectares of mangroves(Watling 1995) and about 150,000 hectares ofcoral reefs.3 Mangroves play key roles intrapping sediments and protecting coastal areasagainst erosion. They are also vital nurserygrounds for coastal fisheries. The impact of sealevel rise and storm surges on mangroves isexpected to be mixed: some expansion might beobserved due to the increased sedimentation ofthe coastal zone; the net impact of erosion,however, is expected to be negative.

Coral reefs are likely to be particularly affectedby climate change. A rise in sea surfacetemperature of more than 1oC could lead toextensive coral bleaching and, if conditionspersist, to coral mortality. Such bleaching eventswere observed during the 199798 El Niñoepisode (Wilkinson and others 1999) and morerecently in Fiji, Tonga and the Solomon Islands

3 This estimate is derived based on the total area of coralreefs in Fiji (an estimated 1 million hectares, according toWRI 1999), and Viti Levus share of the total coastal areaof Fiji (15 percent).

Potential InundationPhysical Impact Inundation costs

(in US$ million)

Sea Level Rise (m)

Scenarioequivalent to

Land inundated (ha)

Percentage oftotal landbelow 10meters altitude

Annualizedlossesa

Incremental capital valueof lost assets during anextreme event b

0.22025 worst-case2050 best-guess 370 0.6 0.3 14.6

0.4─0.52050 worst-case2100 best-guess

3,530 5.9 0.5 30.1

a - Reflects the incremental annual value of the losses due to climate change, or the capital recovery factor. The costs take intoconsideration the impact of a 1 in 50 year storm event.

b - Reflects the incremental cost of capital losses during a 1 in 50 year storm event. Note: For assumptions, see annex A. Source: Background studies to this report

Table 5. Potential Inundation of the Coast of Viti Levu, Fiji, as a Result of Sea Level Rise

11

in April 2000. The deeper water resulting froman increase in sea level could stimulate thevertical growth of corals, but reef response islikely to lag the rise in the sea level by at least40 years (Hopley and Kinsey 1988; Harmelin-Vivien 1994). As a result, many coral speciesmay not be able to adapt sufficiently rapidly to asuccession of bleaching events triggered byhigher sea surface temperatures.

The climate change impact on coral reefs in VitiLevu is projected to cost an estimatedUS$5─$14 million a year by 2050 in lostfisheries, habitat and tourism value (see annexA for detailed assumptions).

B. Impact on Water Resources

Average rainfall could either increase ordecrease by 2050 (see table 2). The impact willdepend to a large extent on the South PacificConvergence Zone (SPCZ). If the SPCZ movesaway from Fiji and the region shifts to a moreEl Niñolike state, Viti Levu could experiencemore pronounced droughts. If the SPCZintensifies near Fiji, average rainfall couldincrease.

It is also possible that Viti Levu wouldexperience greater climate variability, withalternating floods and droughts brought on bymore intense cyclones and ENSO fluctuations.The sequence of four cyclones and two droughtsexperienced in 199299 could reflect the futurepattern of climate variability.

Cyclones. With an average of 1.1 cyclones ayear (Pahalad and Gawander 1999), Fiji has thehighest incidence of cyclones in the SouthPacific. The four tropical cyclones that hit Fijibetween 1992 and 1999 killed 26 people andcaused damages estimated at US$115 million(Fiji Meteorological Services undated). Most ofthe damage occurred on Viti Levu.

Regional studies indicate that cyclone intensitymay increase by 020 percent in the PacificIsland region as a result of climate change(Jones and others 1999). Based on historicalrecords of cyclone damage in Fiji and scientifictheory, a 20 percent increase in maximum wind

speed could result in a 44100 percent increasein cyclone damage (figure 2).4 Taking Fijisaverage annual cyclone damage for the 199299period (US$14.4 million) as a baseline andadjusting the figure to reflect the relative share

4 See Annex A, pages 32-34 for detailed assumptions.

Table 6. Summary of Estimated Annual EconomicImpact of Climate Change on the Coast ofViti Levu, Fiji, 2050 (millions of 1998 US$)

Category Annual damages

Impact on coastal assets: Loss of land to erosion 2.9─5.8 Inundation of land and infrastructure 0.3─0.5

Impact on coral reefs ─ Loss of: Subsistence fisheries 0.12.0 Commercial coastal fisheries 0.0.5─0.8 Tourism 4.8─10.8 Habitat 0.2─0.5 Biodiversity + Nonuse values +

Impact on mangrovesa

Impact on seagrasses +

Total estimated damages >8.4─20.4

+ Likely to have economic costs, but impact not quantified. a Accounted for in the erosion analysis. Note: For detailed assumptions, see annex A. Source: Background reports to this study.

Relationship Between Maximum Wind Speed and Damages Caused by Major Cyclones in Fiji (1983-1997)

Storm Gavin (1985) Joni (1992)

Sina (1990) Gavin (1997)

Eric (1985)

Oscar (1983)

Kina (1993)

0

20

40

60

80

100

0 10 20 30 40 50 60 70 80

Maximum Wind Speed (knots)

Dam

ages

(199

8 U

S$ M

illio

n)

Source: Fiji M eteoro logical Services.. Damages are converted to 1998 costs

Figure 2. Cyclone Wind Speed and Impact in Fiji

12

of Viti Levu in Fijis population, the likelychange in cyclone intensity could cost Viti Levuas much as US$11 million a year by 2050.

Droughts. Fiji experienced four El Niñorelateddroughts between 1983 and 1998. The 1997/98eventone of the worst on recordcauseddamages of US$140$165 million, equivalent toabout 10 percent of Fijis GDP. The droughtaffected food supplies, commercial crops,livestock, and the water supply of schools andcommunities. Droughts of this severity couldwell become the norm in the future. However,due to the scarcity of economic data on pastdroughts in Fiji, it is not possible to separate theeffects of climate variability from those ofclimate change. The incremental impact ofclimate change on drought intensity could onlybe computed for crop losses (see section C).Non-agricultural impacts related to watershortages and nutrition are believed to besubstantial, but could not be quantified.

Water Supply. Among the most importanteffects of climate change are the impacts ofchanges in rainfall on water supply. Models oftwo streams in Viti Levuthe Teidamu andNakauvadra creeksindicate that rainfallvariations could cause a 10 percent change inwater flow by 2050 and a 20 percent change by2100. The direction of the change woulddepend on whether rainfall increases ordecreases. For larger rivers, an increase inrainfall could lead to extensive flood damage.

Figure 3 shows the projected supply anddemand for water in Nadi-Lautoka, a primetourism and urban area of Viti Levu whichserves 123,000 people. Provided the distributionsystem is fully efficient, the impact of adecreasing rainfall scenario would not becomesubstantial until the second part of the century.Under a worst-case scenario and moderatepopulation growth, demand would exceedsupply by 38 percent by 2100─as compared toan 18 percent shortfall in the absence of climatechange. The deficit caused by climate change issmaller than the amount currently lost to leakageand water losses (29 percent), suggesting thatmore aggressive leak repair would be a logicaladaptation strategy.

Table 7 summarizes the quantifiable economicimpacts of climate change on the waterresources of Viti Levu. The estimate of US$0-$11 million reflects only the averageincremental annual costs of more intensecyclones; absolute costs in disaster years couldbe much higher, up to US$44 million for anaverage cyclone. Given the uncertaintiessurrounding extreme eventsand the difficultyassociated with quantifying certain types ofdamagesthese estimates should be viewedprimarily as illustrations of what may happen.

Table 7. Estimated Annual Economic Impact of Climate Change on Water Resources in Viti Levu, Fiji, 2050

Category Annual damage(millions of 1998 US$)

Changes in average rainfall +

Increased cyclone intensity 0─11.1

Increased severity or frequency of El Niño related drought

++

Total 0─11.1+ Likely to have significant economic costs, but impact could not be

quantified. Source: Background studies to this report.

0

40

80

120

160

1990 2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100

Year

Wat

er V

olum

e (M

L) SustainableSupply

Most likely scenario

Worst case scenarioDemandProjections

Demand under Population growth:

High

Mid

Low

Figure 3. Estimated Supply and Demand of Water inWestern Viti Levu, under a Decreasing Rainfall Scenario

Note: Assumes future demand to be 300 l/capita/day, 25% loss, yield 98 million l/day.Sources: JICA 1998 and background studies to this report.

13

C. Impact on Agriculture

Changes in rainfall, temperature, and climatevariability will affect agricultural production inViti Levu. An 8 percent increase in rainfall (asexpected in 2050) would benefit most cropsexcept yams, while a drier climate (an 8 percentdecrease in rainfall) would hurt most crops,particularly sugarcane (figure 4).

The impact of climate change on agriculture inViti Levu is estimated to cost about US$14million a year by 2050 (table 8). This estimatereflects annual average costs; damages in an ElNiño year could be much greater as indicated bythe 1997/98 drought, which cost Viti Levu someUS$70 million in lost crops (UNDAC 1998).

The most significant economic damage wouldbe on sugarcane, which accounts for 45 percentof Fijis exports and is cultivated primarily inViti Levu. But losses of traditional crops, suchas yams and taro, could have a substantial effecton subsistence economies in Viti Levu.

Sugarcane. Sugarcane is particularly sensitiveto droughts: the 1983 and 1997/98 events, forexample, resulted in a 50 percent loss inproduction (figure 5).5 In the future, increases inrainfall during good years may offset theimpacts of warmer temperatures, with littlechange in sugarcane production. However, awarmerand possibly drierclimate could leadto more intense droughts during El Niño years.Using the impact of the 1997/98 drought asrepresentative of the intensity of future eventsand assuming a drought frequency similar to thatobserved in 1983─98 (one drought every fouryears), the following projections can be madefor the next 2550 years:

• Sugarcane production is likely to total 2million metric tonsjust half of output in anormal yearevery four years, or 25percent of the time (4 out of 16 years).

• Sugarcane production is likely to total 3million metric tonsthree-quarters ofoutput in a normal year31 percent of the

5 The agricultural climate change model used by the study(Plantgro) did not provide reliable scenarios for sugarcane.The impacts were thus estimated based on historical data.

time (5 out of 16 years) as a result of theresidual effects of cyclones and droughts.

• Sugarcane production might total 4 millionmetric tonsthe normal level of output44percent of the time (7 out of 16 years).

Under this scenario, the future production ofsugarcane could average 3.2 million metric tonsa year, a drop of 9 percent from the 198398average level of 3.5 million metric tons. Theresulting economic losses would be aboutUS$14 million a year by 202550, assumingconstant sugar prices.

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000Pr

oduc

tion

('000

MT)

Year

El Nino-Related Droughts

Figure 5. Sugarcane Production in Fiji, 1983─1998

Figure 4. Likely Impacts of Climate Change onAgriculture in Viti Levu, Fiji

Meanrainfall

Increaseddrought

frequencyand

magnitude

Improvedproduction

of most crops(but yam

productionmay decline)

Increase Decrease

Decreasedproduction

• SugarCane

• Taro• Cassava

Increasedmagnitude

oftropical

cyclones

Source: Official Fiji Statistics.

14

Table 8. Estimated Economic Impact of Climate on Change on Agriculture in Viti Levu, Fiji, 2050

Impact of change in average rainfalland temperature

Impact of change in rainfall, temperature,and climate variability (ENSO)

Crop

Currentproduction

(US$ thousands)Economic Impact (US$ thousands)

Change inaverage yield

(percent)Economic Impact (US$ thousands)

Change inaverage yield

(percent)

Sugarcane 147,200 ─ ─ -13,700 -9Dalo (Taro) 800 -40 +9 -5 +1 -111 +6 -15 +1Yam 1,600 -76 +63 -5 +4 -164 +54 -11 +4Cassava 2,100 -189 -105 -9 -5 -242 -128 -12 -6

Total -13,800─14,200 Not available. Minus signs indicate an economic cost. Plus signs indicate an economic benefit (from rainfall increases).

Note: Ranges reflect best-guess and worstcase scenarios under two different climate change models. See annex A for assumptions used.Source: Background studies to this report.

The impact on the Fijian economy is expectedto be substantial, but localized. In 1997/98, forexample, a 26 percent decline in sugarcaneproduction value led to a decline in GDP of atleast 1.3 percent (Ministry of Finance 1999).More importantly, Viti Levu could suffer a 50percent drop in sugarcane production everyfourth year due to stronger El Niños. Theseperiodic droughts could well prove to be themost disruptive to the Fijian economy oncepreferential trade agreements are phased out.

Food Crops. By 2050 climate change may costViti Levu some US$70─520,000 in lost foodcrop production (table 8). Projected changes inaverage climate conditions (temperature andrainfall) would have little effect on daloproduction. In El Niño years, however, the daloyield could be reduced by 3040 percent ofcurrent levels (figure 6).

Yam production would also remain relativelyunaffected by changes in average conditions.The response to climate variability is theopposite of dalo. During El Niño events,production might be expected to remain thesame or even increase. Production could declineby nearly 50 percent, however, as a result ofwetter or La Niñatype conditions. Thisresponse is consistent with the traditional use ofyam and dalo as dry and wet season crops.

Cassava output is expected to decline as a resultof changes in average climate conditions, withyields falling 5─9 percent by 2050 (table 8).Productivity could also worsen with future

1990

Current El Nino

2050 El Nino

Note: Shaded areas show land suitable for cultivation.Source: Background studies to this report.

Figure 6. Effect of El Niño─induced Droughts onTaro Cultivation Area and Yields in Viti Levu

15

Table 9. Loss of Lives and Damages from Recent Cyclones in Fiji, 1983─97

Cyclone Number oflives lost

Number ofpeoplemissing

Damages(1998 US$million)

Oscar 9 76Eric 25 33Storm Gavin 7 3 1Sina 17Joni 1 1Kina 23 96Gavin 12 6 18

Total 77 9 242

Source: Fiji Meteorological Services.

climate variability, particularly under anintensified La Niña.

Yaqona (kava) showed little response to climatechange or El Niño/La Niña anomalies. Yaqonaharvests were affected by the 1997/98 drought,however. The crop is best suited to upland areasin central and southwestern Viti Levu, which areleast affected by drought. This suggests that ifproduction expands into nontraditional areas,yaqona could become increasingly susceptible toclimate variation.

D. Impact on Public Health

Climate change could have significant impactson public health as a result of highertemperatures (0.9─1.3o C by 2050), changes inwater supply, and decline in agricultureproduction. The impacts could include:

❏ Direct impacts on public safety, includinginjuries, illness, and loss of lives due tocyclones or droughts.

❏ Indirect effects, such as increased incidenceof vectorborne diseases (dengue fever andmalaria), waterborne diseases (diarrhea), andtoxic algae (ciguatera).

❏ Nutrition-related diseases, particularlymalnutrition and food shortages duringextreme events.

Public health impacts are likely to beparticularly severe for the 12-20 percent ofhouseholds in Fiji that live below the povertyline (UNDP and Government of Fiji 1997). Poorhouseholds are more vulnerable to the impactsof climate change because of their greaterpropensity for infectious diseases, limited accessto medical services, substandard housing, andexposure to poor environmental conditions.Many of the poor are also landless and(particularly in urban areas) may lack access totraditional safety nets that assisted them in timesof disaster. Poverty is thus both a contributor tovulnerability as well as an outcome of climate-related events.

Quantifying these impacts is difficult, yet it isalso vital for the development of appropriatepublic health policies. Based solely on the likelyincrease in dengue fever and diarrheal disease,the public health impacts of climate change inViti Levu are estimated at US$1$6 million ayear by 2050. This figure is almost certainly anunderestimate, as it does not take into accountthe costs of fatalities, injuries, or illnesses fromcyclones or droughts; the costs of nutrition-related diseases; or the indirect impact of climatechange on the poor and the most vulnerable,including infants.

Public Safety. Fiji has lost more than 77 peopleto cyclones over the past 20 years (table 9).Injuries and illnesses caused by extreme eventsare also believed to be significant. Cyclone Kinaalone caused 23 deaths in 1992/93, in addition toUS$96 million in damages (Fiji MeteorologicalServices undated). An increase in cycloneintensity, as envisaged, could increase theimpact on public safety by as much as 100percent relative to what is observed today. Anaverage cyclone in the future might come toresemble the impacts of cyclone Oscar (1983) orEric (1985).

Dengue Fever. Dengue fever is a growingpublic health problem in Fiji. The most recentepidemicwhich coincided with the 1997/98droughtaffected 24,000 people and left 13

16

dead, at a cost of US$3$6 million (Koroivueta,personal communication; Basu and others 1999).

Climate change is expected to cause significantincreases in the frequency, severity and spatialdistribution of dengue fever epidemics. Highertemperatures would increase the biting rate ofmosquitoes and decrease the incubation periodof the dengue virus.

In 1990, 53 percent of Viti Levu was at low riskof a dengue epidemic. By 2100 less than 21percent of the island, all in the interiorhighlands, may remain at low risk. Under theworst-case scenario, up to 45 percent of theisland could be at high or extreme risk of adengue fever epidemic (table 10). Theeconomic impact would average about US$1-$6million a year by 2050 (table 11).

Climate change could also result in:

• A 2030 percent increase in the number ofcases of dengue fever by 2050 and as muchas a 100 percent increase by 2100 (under aworst-case scenario).

• Dengue fever becoming endemic (that is,occurring all the time rather than in

epidemics).

• A change in seasonality, so that denguefever outbreaks could occur in any month.

• The emergence of more severe forms of thedisease, such as dengue hemorrhagic feverand dengue shock syndrome, resulting inhigher fatality rates.

Diarrheal Disease. Diarrheal disease is likely tobecome more common in a warmer and wetterworld. More intense droughts and cyclonescould also increase the incidence of diarrhea bydisrupting water supplies and sanitation systems.

Quantitative analysis indicates that a 1oCincrease in temperature could result in at least100 additional reports of infant diarrhea amonth. Since the actual incidence of diarrhea isat least 10 times the incidence of reported cases,a 1oC rise in temperature, as expected by 2050,could lead to 1,000 additional cases of infantdiarrhea a month. These results can be used,with lower levels of confidence, to estimate thepotential impacts of diarrhea in children andadults. The economic costs of climate change ondiarrheal disease are estimated to averageUS$300,000─$600,000 a year by 2050 (table

Table 10. Potential Impact of Climate Change on Dengue Fever in Viti Levu, Fiji

Likely changes Baseline(1990)

2025 2050 2100

Estimated change in number of cases (percentage change) 0% 10% 20─30% 40─100%

Epidemic potential in Viti Levu (in percentage of land area) a Low risk 53% 38─39% 25─31% 7─21% Medium risk 47% 61─62% 69─72% 48─72% High risk 0─3% 7─41% Extreme risk 0─4%Seasonality Nadi Seasonal Seasonal Seasonal to all year All year Suva Seasonal Seasonal Seasonal to extended

seasonProlongued

season to all yearFrequency of epidemics 1 in 10 years ─────────Likely increase ──────────────Severity of strains ──────────────── Likely increase ──────────────

a - Epidemic potential is an index that reflects the efficiency of transmission in a particular area.Note: Ranges represent the most likely and worst-case scenarios in the CSIRO9M2 General Circulation Model.Source: Background studies to this report. For assumptions, see annex A.

17

11).

Other Public Health Impacts. Fiji is presentlymalaria-free: the strict border controls andquarantine requirements have so far beensuccessful in keeping the malaria vector(Anopheles) away. Climate change couldincrease the risk of malaria, though modelingresults indicate that the epidemic risks in Fijidue to climate change are small.

Climate change could also increase the risk offilariasis. However, Fiji has started an intensiveprogram to control filariasis and is expected toeradicate the disease in 5─10 years (Koroivueta,personal communication).

Nutrition-Related Diseases. More intensecyclones and droughts are likely to increase theincidence of nutrition-related diseases, assubsistence crops and fisheries are affected. Theimpacts may be similar to those experiencedduring the 1987 and 1997/98 droughts, whenmilk production fell 50 percent and some US$18million in food and water rations had to bedistributed (UNDAC 1998). Up to 90 percent ofthe population in western Viti Levu requiredemergency food and water rations. Loss ofagriculture income and failure of householdgardens also caused protein, vitamin, andmicro-nutrient deficiency, particularly amongyoung children and the poor.

Table 11. Estimated Annual Economic Impact of Climate Change on Public Healthin Viti Levu, Fiji, 20252100

(millions of 1998 US$)

Event 2025 2050 2100

Cyclones and droughtsa Likely to be substantialDengue fever 0.3─2.3 0.5─5.5 0.7─15.9Diarrheal diseases 0.2 0.3─0.6 0.6─2.2Nutriton-related illnesses + + +

Total estimated costs 0.5─2.5 0.8─6.1 1.3─18.1

─ Not available.+ No quantifiable data available, but damages are likely to be substantial.a. The effect of cyclones and droughts on health could not be calculated, though the overall impact of cyclones was taken into

account in section B.Note: For assumptions, see annex A.Source: Background studies to this report.

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19

Chapter 4 Impact of Climate Change on Low Islands

The Tarawa Atoll, KiribatiLike most atolls, Tarawa (30 km2) is veryvulnerable to sea level rise. Most of the land isless than 3 meters above sea level, with anaverage width of only 430450 meters (Landsand Survey Division undated). While Tarawalies outside the main cyclone belt, it issusceptible to storm surges and to droughts,particularly during La Niña events.

The population density of the atoll is unevenlydistributed, with South Tarawa (the capital)approaching 5,500 people per square kilometer,while North Tarawa remains sparsely populated,with less than 50 people per square kilometer.As available land in South Tarawa becomesscarcer, development in North Tarawa isexpected to accelerate.

Box 4. Tarawa at a Glance

Tarawa, Kiribati Climate• Temperature: 26─32°C (average 31°C).• Average rainfall in central Tarawa: 2,749 milimeters.Major influences:

• Intertropical Convergence Zone.• South Pacific Convergence Zone.• El Niño Southern Oscillation (ENSO).Extreme events:• Droughts (often associated with ENSO).• Tropical cyclones rarely affect Kiribati (but storm surges do).Population:• Population of Kiribati: 77,658 in 1995 (35,000, or 45% in Tarawa)• Average annual growth rate: 1.4% (3% in South Tarawa).• Population Density: 250/km2 (Gilbert Islands); 1,800/km2 (South

Tarawa).• Growing urbanization.

Economy (Kiribati):• GDP (1998): US$47 million.• Average annual growth: 4.7% (1990─96).• Dominated by public sector.• Significant exports: copra, fish.• Subsistence agriculture (coconut, taro, breafruit, pandanus) and

fisheries vital.

Future Population TrendsIncreasing population density:• Very high population density on South Tarawa.• Accelerated population growth in North Tarawa.

Implications:• Denser urban structures.• Industrial and commercial development.• Change from traditional housing styles and materials.• Increase in proportion of squatter housing.• Increase in coastal infrastructure.

Future Economic Trends• Continued dependence on natural resources.• Agriculture will continue to be important in subsistence production,

and will remain a small export earner.• Cash economy will become increasingly important, but

subsistence economy will remain significant.• Continued dependence on foreign aid.

Future Environmental Trends• Environmental degradation in densely populated areas.• Continued degradation and irreversible damage to

mangroves and coral reefs.• Increased problems of waste disposal (sewage,

chemical, and solid waste pollution).

Future Sociocultural Trends• Increasing role of cash economy.• Changes in food preferences toward imported foods.• Increased noncommunicable diseases associated with nutritional

and lifestyle changes.• Increased poverty and social problems in urban areas.

20

Tarawa is already becomingincreasingly vulnerable to climatechange due to high populationgrowth rates and in-migrationfrom outer islands, accelerateddevelopment, shoreline erosion,and rising environmentaldegradation. In such a fragileand crowded environment, evensmall changes can have a largeimpact. Socioeconomic trendspoint to a continuing rise in theatolls vulnerability in the future(box 4).

By 2050, under the climatechange scenarios shown in table2, Tarawa could experienceannual damages of aboutUS$8─$16 million (table 12).This estimate takes into accountonly the potential impacts ofclimate change on coastal areas(US$7$13 million a year) andwater resources (US$1$3million a year). The cost ofseveral other importantimpactssuch as loss ofagriculture crops and effects onpublic healthcould not beestimated because ofinsufficient data. Indicationssuggest that these damages maybe substantial.

These costs reflect annualaverage losses due to climatechange. In years of strong storm surge, Tarawacould face capital losses of up to US$430million in land and infrastructure assetsdestroyed by inundation. Relocation ofcommunities might be needed if the loss of landand freshwater supplies become critical.

Climate change is thus likely to place asubstantial burden on the people and economy ofKiribati. The projected losses could becatastrophic for a country with a 1998 GDP of

only US$47 million. These losses, however,assume no adaptation. Communities wouldlikely adapt to sea level rise by elevating theirhouses or moving further inland, particularly ifthe changes were gradual. Nevertheless, sealevel rise could profoundly affect the economyof Kiribati by inundating the causeways thatnow link the islets of Tarawa, thus disruptingsocio-economic links. Much of the impact ofclimate change will ultimately depend on theextent to which proactive adaptation measuresare adopted.

Table 12. Estimated Annual Economic Impacts of Climate Changeon Tarawa, Kiribati, 2050

(millions of 1998 US$)

Impact Annualdamagesa

Level ofCertainty

Likely cost ofan extremeeventb

Impact on coastal areasLoss of land to erosion 0.1─0.3 Low ─Loss of land and infrastructure to inundation 7─12 Low 210-430Loss of coral reefs and related services 0.2─0.5 Very Low (storm surge)

Impact on water resourcesReplacement of potable water supply due to change in precipitation, sea level rise, and inundation

1─3 Low ─

Impact on agricultureAgriculture Output Loss + Low ─

Impact on public healthIncreased incidence of diarrheal disease ++ Low ─Increased incidence of dengue fever + Low ─Increased incidence of ciguatera Low ─Impact of climate change on public safety and on the poor

+ Very Low ─

Potential increase in fatalities due to inundation, and water-borne or vector-borne diseases

+ Low ─

Total estimated damages >8─16+ ─+ Likely to have economic costs, but impact not quantified. ─ Not available.a Reflects incremental average annual costs of climate change, equivalent here to the capital recovery cost factor of land and infrastructure damaged by inundation, using a discount rate of 10 percent and a 10─ year period.b Reflects financial damages to land and infrastructure caused by sea level rise and storm surge during a 1 in 14─ year storm event. For detailed assumptions, see annex A.Source: Background reports to this study.

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A. Impact on Coastal Areas

Climate change is likely to affect Tarawas coastthrough shoreline displacement resulting fromthe rise in sea level (by 0.2─0.4 meters by2050), through inundation and storm surge, andthrough coastal erosion due to the effect ofincreases in sea surface temperature and sealevel on coral reefs.

To model the impact of coastal erosion andinundation, two representative sections of theTarawa coast were selected: the islands ofBuariki and Naa in North Tarawa and Bikenibeuin South Tarawa (see map in box 4). Theseareas represent about 20 percent of the area ofNorth Tarawa and about 7 percent of the area ofSouth Tarawa.

Coastal Erosion. Models of shorelinedisplacement indicate that while all of the atollsislands are undergoing coastal erosion, the lossof land due to sea level rise is likely to berelatively smalla maximum of 3.2 percent ofland by 2100 for Buariki and 3.9 percent forBikenibeu, leading to economic damagesaveraging US$0.1-$0.3 million a year by 2050.

Higher rates of erosion could arise if sedimentsupply decreases, which may happen if coralreefs are weakened by climate change. Eventhese small changes, however, could causesignificant impacts given the atolls narrowwidth and population concentration.

The islands are expected to become narrowerand higher, with Buariki facing a shorelinedisplacement of 30 percent of the island width.The frequent overwash would result in a build-up of sediments in the center of the islands.These sediments would have to be removed, orinfrastructure would have to be displaced.

Coastal Inundation. As a result of ENSOevents, Tarawa already experiences significantnatural fluctuations of about 0.5 meters in sealevel. These fluctuations will affect theinundation potential of the atoll, particularlywhen combined with storm surges and theprojected increase in sea level.

The coastal inundation impacts were modeled byraising the mean high water spring level (themaximum water level reached during spring

Table 13. Likely Impact on Buariki and Bikenibeu, Tarawa, Kiribati of Inundation Caused by Sea Level Rise, 2025, 2050 and 2100

Buariki BikenibeuProjected losses Projected losses

Projected risein sea level(meters)

Scenario equivalent to Percentageof landarea

affected

Structures(number)

Roads(kilometers)

Percentageof landarea

affected

Structures(number)

Roads(kilometers)

0.2 2025 worst-case2050 best-guess

18% 196 (59%) 6.55 (77%) 0% 0 0

0.4-0.5 2000 baseline + storm surge2025 best-guess + storm surge

2050 worst-case2100 best-guess

30% 213 (64%) 6.55 (77%) 2% 34 ( 2%) 0

2050 best-guess + storm surge 55% 229(69%) 7.5 (89%) 25% 423(27%) 1.3(29%)

1.0 2050 worst-case +storm surge2100 best-guess + storm surge

2100 worst-case

80% 245 (74%) 8.5 (100%) 54% 986 (63%) 2.83( 66%)

1.5 2100 worst-case + storm surge 85% 316 (95%) 8.5 (100%) 80% 1302 (84%) 4.36 (100%)

Notes: Storm surges are based on 1 in 14-year event (Solomon 1997).Source: Background studies to this report.

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tides) by the projected increase in sea level.The sea level rise scenarios were alsocombined with the effects of stormsurges likely to occur once every 14years (Solomon 1997).

The results indicate that under a best-guess scenario, 18 percent of Buarikicould be inundated by 2050 (table 13).By 2100 up to 30 percent of Buarikicould be inundated. The impact onBikenibeu would be relatively minor (2percent inundation). Storm surges,however, could increase damagessignificantly, with up to 80 percent ofBuariki and 54 percent of Bikenibeuinundated by 2050.

Projected losses in infrastructure androads could be substantial. Under aworst-case scenario, the village ofBuariki could be inundated by 2050, ascould 59 percent of the structures and77 percent of the roads. In Bikenibeu,significant impact on infrastructure isnot be expected to occur until 2100under a worst-case scenario, but it couldthen become substantial, with 66100percent of all roads lost under thecombined effects of storm surge and sealevel rise (figure 7).

The projected loss of land and structuresis based on existing infrastructure. Actuallosses in 2025 and 2050 could be substantiallyhigher, particularly if Tarawa were affected bylarger storm surges (such as one in 50-100 yearevents). The damage could be moderated ifpopulation growth was contained andredistributed to less urbanized areas.

Extrapolating the losses for Buairiki andBikenibeu to the rest of North and SouthTarawa, the projected financial losses of landand structure assets in Tarawa could averageUS$7─$12 million a year by 2050 (table 14).During years of actual storm surges, Tarawacould experience losses of capital assetsapproaching US$210 to $430 million.

The analysis assumes the loss of all land andstructures affected by inundation and stormsurge, which may overly pessimistic. However,

the rise in sea level will amount to a condition ofpermanent inundation which, combined withthe existing standard of housing in Tarawa, islikely to result in the loss of structures unlessadaptive action is undertaken. Other factors inthe analysissuch as more severe storms andincreases in their frequencyare likely to havebeen underestimated.

Mangroves and Coral Reefs. Tarawa has lostsome 70 percent of its mangroves since the1940s, and only 57 hectares remain (Metz 1996).Hence the impact of sea level rise is expected tobe relatively minor.

Healthy coral reefs may respond to increases insea level by growing vertically. In fact, thehistorical accretion rate of the Tarawa reef flat(8 milimeters a year) exceeds the rate of

A: Present status B: Residual island under a worst case scenario, 2100; C: Residual island under worst case scenario and storm surge, 2100 Source: Background studies to this report.

Figure 7. Projected Inundation of Bikenibeu Island Tarawa, Kiribati under Worst-Case Scenario

23

projected sea level rise (Marshall and Jacobsen1985). However, many corals may not be ableto adapt to warmer sea surface temperatures andincreased concentration of carbon dioxide in theatmosphere, both of which inhibit coral growth.As stated previously, vertical coral growth islikely to lag the increase in the sea level by atleast 40 years. This could create a high-energywindow, allowing waves of increasing strengthto reach the shore. In addition, while the reef isgrowing vertically the amount of sediment forisland building could decline.

For heavily damaged reefs affected byincreased bleaching events a number ofconsequences are likely. These includefurther depletion of reef fisheries, failureof the reef to act as an effective buffer ofwave energy, and increased islandinstability as sediment resources decline.

The economic losses of coral reefdegradation attributed to climate changewould be in the order of US$200,000$500,000 a year primarily as a result oflost fish production (table 12). Thisestimate does not include loss of coastalprotection, which was reflected in theinundation analysis, or other importantreef functions that could not bequantified.

B. Impact on Water ResourcesClimate change is likely to affect the waterresources of Tarawa through variations inrainfall, evapo-transpiration (caused by a rise intemperatures), increases in the sea level, andextreme events (figure 8). Average rainfall isexpected to either decrease by 8─11 percent, orincrease by 5─7 percent by 2050 (most modelspredict an increase). The economic lossesresulting from these changes are estimated atabout US$13 million a year (in 1998 dollars)by 2050.

Figure 8. Likely Impact of Climate Change onWater Resources in Tarawa, Kiribati

Potential Inundation Costs (in US$ million)Scenario equivalent to Annualized lossesa Capital value of lost assets

during a storm surge eventb

2050 best-guess 6.6 158.0

2050 worst-case 12.4 374.62100 best-guess

2100 worst-case 69.7 497.3

a - Reflects the annual value of the losses, or the capital recovery factor. The costs take into consideration the incremental impact of a 1 in 14 year storm event. b - Reflects the incremental cost of capital losses during a 1 in 14 year storm event.Note: For assumptions, see annex A.Source: Background studies to this report

Table 14. Estimated Economic Impact of Inundation Caused by Sea Level Risein Tarawa, Kiribati, 2050 and 2100

(millions of 1998 US$)

Coastal Effectsof

Climate ChangeMean Rainfall

Increased DroughtFrequency &Magnitude

ImprovedWater

Resources

Increase Decrease

ReducedQuantity

ReducedQuality

IncreasedInundation

Groundwater

DecreasedRain

WaterCollection

andStorage

Loss ofLand

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Tarawa receives less rainfall than surroundingatolls. The population relies primarily ongroundwater resources, complemented byrainfall collected from roofs and desalinatedwater (a desalination plant has been operationalsince 1999). Population growth and economicdevelopment are likely to place considerablepressure on these resources over the nextcentury.

Water Supply. Models of climate change impacton Tarawas main groundwater supply (Bonriki)indicate the following:

• Changes in rainfall. By 2050 a 10 percentdecline in rainfall could cause a 14 percentreduction in groundwater recharge. If, bycontrast, average rainfall increased by 7percent, the groundwater recharge wouldincrease 5.5 percent.

• Changes in evapo-transpiration. Evapo-transpiration would increase if the climatewarmed, but its effects on groundwaterrecharge would be much milder than theeffect of changes in rainfall. A 10 percentincrease in annual evapo-transpiration couldresult in a 6 percent decline in groundwaterrecharge.

• Changes in sea level. A rise in sea level of0.4 meters (the worst-case scenario in 2050)would have little effect on the groundwatersupply and could even raise its volume, asthe groundwater table (the top of thefreshwater lens) would tend to rise while itsbase remained relatively unaffected.However, if the width of the islands werereduced by inundationwhich is likely─thethickness of the groundwater could decline29 percent.

The combined effect of these impacts is shownin table 15. By 2050 if rainfall declines by 10percent, the sea level rises by 0.4 meters, and theislands width is reduced by inundation, thethickness of the groundwater could decline asmuch as 38 percent. The resulting economicimpacts, extrapolating for the Tarawa atoll,would be on the order of US$1.4─$2.7 million ayear. If, by contrast, average rainfall increasedin the future, the annual economic costs wouldamount to US$0.7─$1.3 millio