Vulnerability and Adaptation Assessments Hands-On Training Workshop

Coastal Resources: Analytical Approaches

OutlineIntroductionSea level rise Predictions and uncertaintiesScenariosGlobal processesLocal uncertaintiesImpactsAdaptation and shoreline management

Outline (continued)Methods to assess impacts of sea level riseLevels of assessmentScreeningVulnerability PlanningReview of African region situationModelsData sourcesDIVA

Climate Change and Coastal ResourcesCoastal resources will be affected by a number of consequences of climate change, including:Higher sea levelsHigher sea temperaturesChanges in precipitation patterns and coastal runoffChanges in storm tracks, frequencies, and intensities

The Main Biophysical Effects of Relative Sea Level Rise

Some Climate Change Factors

Current Global Predictions of Sea Level RiseIPCC Third Assessment Report (TAR) range for global-mean rise in sea level is between 9 cm and 88 cm by 2100Change outside this range is possible, especially if Antarctica becomes a significant sourceThere is a commitment to sea level rise even if atmospheric GHG concentrations are stabilized

Global-Mean Sea Level Rise 1990 to 2100 (SRES scenarios)Houghton et al., 2001

Processes Controlling Sea-LevelChangeRelative sea-level changes

Ocean Water VolumeControlled by:Ocean temperature thermal expansionMelting of land-based iceSmall glaciersGreenlandAntarcticaThe hydrological cycle (including human influence)

Uncertainty in Local PredictionsRelative sea level rise: global and regional components plus land movementLand uplift will counter any global sea level riseLand subsidence will exacerbate any global sea level riseOther dynamic oceanic and climatic effects cause regional differences (oceanic circulation, wind and pressure, and ocean-water density differences add additional component)

Sea Level Rise at New York City1850 to 2100IPCC TAR range due to SRES emission scenariosMcCarthy et al., 2001

Land Subsidence

Other Climate Change(Hurricane Katrina)

Elevation and Population Density Maps for Southeast Asia

Population and Population Density vs. Distance and Elevationin 1990

Coastal Megacities (>8 million people)Forecast for 2010

National Vulnerability Profiles

Deltaic Regions

Atolls

Biogeophysical Effects of Sea Level RiseDisplacement of coastal lowlands and wetlandsIncreased coastal erosionIncreased flooding (frequency and depth)Salinization of surface and groundwaters Plus others

Socioeconomic ImpactsLoss of property and landIncreased flood risk/loss of life Damage to coastal protection works and other infrastructureLoss of renewable and subsistence resourcesLoss of tourism, recreation, and coastal habitatsImpacts on agriculture and aquaculture through decline in soil and water quality

Definition of Impacts

Shoreline Management and Adaptation

Responding to Coastal Change(including sea level rise)

Retreat

Accommodation

Protect SoftHard

Shoreline Management and Adaptation (2)

Adaptation MethodsRetreatManaged retreatRelocation from high risk zonesAccommodationPublic awarenessNatural disaster management planning

Adaptation Methods (continued)ProtectHard optionsRevetments, breakwaters, groinsFloodgates, tidal barriersSoft optionsBeach/wetland nourishmentDune restoration

Example Approach to Adaptation MeasuresCaribbean small island developing country Climate change predictionsRise in sea level Increase in number and intensity of tropical weather systemsIncrease in severity of storm surgesChanges in rainfall

Example Approach to Adaptation Measures (continued)Coastal impactsDamage to property/infrastructure Damage/loss of coastal/marine ecosystemsDestruction of hotels and tourism facilitiesIncreased risk of diseaseDamage/loss of fisheries infrastructureGeneral loss of biodiversitySubmergence/inundation of coastal areas

Example Approach to Adaptation Measures (continued)Adaptation (retreat, protect, accommodate)Improved physical planning and development controlStrengthening/implementation of EIA regulationsFormulation of Coastal Zone Management PlanMonitoring of coastal habitats, including beaches Formulation of national climate change policyPublic awareness and education

Methods to Assess Impacts of Sea Level RiseSea level rise scenariosLevels of assessmentScreening assessmentVulnerability assessmentErosionFloodingCoastal wetland lossPlanning assessment

Coastal Vulnerability andRisk AssessmentThree levels of assessmentScreening assessment (3-6 months)Vulnerability assessment (1-2 years)Planning assessment (ongoing)

Screening AssessmentRapid assessment to highlight possible impacts of a sea level rise scenario and identify information/data gapsQualitative or semiquantitativeStepsCollation of existing coastal dataAssessment of the possible impacts of a 1-m sea level riseImplications of future developmentPossible responses to the problems caused by sea level rise

Step 1: Collation of Existing DataTopographic surveysAerial/remote sensing images topography/ land coverCoastal geomorphology classificationEvidence of subsidenceLong-term relative sea level riseMagnitude and damage caused by floodingCoastal erosionPopulation densityActivities located on the coast (cities, ports, resort areas and tourist beaches, industrial and agricultural areas)

Step 2: Assessment of Possible Impacts of 1-m Sea Level RiseFour impacts are consideredIncreased storm floodingBeach/bluff erosionWetland and mangrove inundation and lossSalt water intrusion

Step 3: Implications of Future DevelopmentsNew and existing river dams and impacts on downstream deltasNew coastal settlementsExpansion of coastal tourismPossibility of transmigration

Step 4: Responses to the Sea Level Rise ImpactsPlanned retreat (i.e., setback of defenses)Accommodate (i.e., raise buildings above flood levels)Protect (i.e., hard and soft defenses, seawalls, beach nourishment)

Screening Assessment Matrix Biophysical vs. Socioeconomic Impacts

Vulnerability Assessment

The Coevolving Coastal System

Barriers to Conducting Vulnerability AssessmentsIncomplete knowledge of the relevant processes affected by sea level rise and their interactionsInsufficient data on existing physical conditionsDifficulty in developing the local and regional scenarios of future changesLack of appropriate analytical methodologiesVariety of questions raised by different socio-political conditions

Controls on Coastal Positionlittoral sedimentsupply (ve)sea-levelchangeantecedentphysiographyboundary conditions (external)lower shorefacebackbarrieruppershorefacebypassingcross-shelf transportinletresuspension & inlet bypassingfluvial-delta inlet bypassingcoastal tractBDCAinner-shelf sandmid-shelf mudmarine sand wedgelagoon basin mud

Beach Erosion

Bruun Rule

Bruun Rule (continued)R = G(L/H)Swhere: H = B + h*

R = shoreline recession due to a sea-level rise Sh* = depth at the offshore boundaryB = appropriate land elevation L = active profile width between boundariesG = inverse of the overfill ratio

Limitations of the Bruun RuleOnly describes one of the processes affecting sandy beachesIndirect effect of mean sea level rise Estuaries and inlets maintain equilibrium Act as major sinksSand eroded from adjacent coastIncreased erosion ratesResponse time best applied over long timescales

FloodingIncrease in flood levels due to rise in sea levelIncrease in flood riskIncrease in populations in coastal floodplainAdaptation Increase in flood protectionManagement and planning in floodplain

Coastal Flood Plain

Global Incidence of Flooding No Sea Level Rise0 10 20 30 People Flooded (Millions/yr)19902020s2050s2080sTime (years)

Vulnerable RegionsMid-estimate (45 cm) by the 2080s

Impacts of Flooding on Arable Agriculture in 2050 No AdaptationReference (1990)Land unavailable for arable Agriculture (% cell)Low climate change

High climate change

Global Impacts of Coastal Flooding in 2050 Effects of MitigationPeople flooded (Millions/yr)

The Thames Barrier

Flood Methodology

Ecosystem LossInundation and displacement of wetlandse.g., mangroves, saltmarsh, intertidal areasAreas provideFlood protectionNursery areas for fisheriesImportant for nature conservationLoss of valuable resources, tourism

Coastal Ecosystems at RiskKEY: mangroves, o saltmarsh, x coral reefs

Coastal Squeeze (of coastal wetlands)(a) no hard defenses(b) hard defensesSea Level Rise

Mangrove Swamp

Areas Most Vulnerable to Coastal Wetland Loss

Saltmarsh Losses to 2050Present day loss rateHigh Climate ChangeLow ClimateChange

Wetland Loss Model StructureRelative Rate of Sea LevelRise ScenariosRate of Sea Level Rise ScenariosVertical Wetland ResponseWetland Loss Tidal RangeNoLossCoastal Geomorph-ologyMigration Potential Corrected wetland lossCoastal Population DensityHorizontal Migration Assessment

Wetland Vertical Response ModelRSLR* = RSLR/TRwhere:RSLR = the rate of relative sea level rise (meters/century)TR = the mean tidal range on spring tides in meters

RSLR* > RSLR*crit lossRSLR* RSLR*crit no loss

Planning AssessmentOngoing investigation and formulation of policyRequires information onRole of major processes in sediment budgetIncluding human influencesOther climate change impactsExample of assessment from the UKCombined flood hazard and erosion assessment

The ProblemCliff Protection Has Local and Wider Effects

ErosionOften Exported Alongshore

Coastal Flood Risk Exacerbated by Declining Sediment InputBeach evolution

Defense degradation/upgrades

Socioeconomic changes

Sea level rise

Increased storminess

Changing loads

Goals for Planning AssessmentFor future climate and protection scenarios, explore interactions between cliff management and flood risk within sediment sub-cell (in Northeast Norfolk)In particular, quantifyCliff retreat and associated impactsLongshore sediment supply/beach sizeFlood riskIntegrated flood and erosion assessment

Method for Planning Assessment

Bathymetry and Wave ModellingNearshore sandbankOffshore sandbank

SCAPE Model of Cliff Retreat

Future PolicyMaintain Defenses, 6 mm/yr Sea Level RiseSheringham

Cromer

OverstrandTrimmingham

Mundesley

Bacton

Happisburgh

Future PolicyAbandon All Defenses, 6 mm/yr Sea Level RiseSheringham

Cromer

OverstrandTrimmingham

Mundesley

Bacton

Happisburgh

Policy ComparisonMaximum Retreat at Abandoned DefensesHold existing defensesAbandon all defensesSheringham

Cromer

OverstrandTrimmingham

Mundesley

Bacton

Happisburgh

Erosion Visualization Protection Abandoned (10 year time steps)

Conclusions45 sea-level/wave/protection scenario combinations assessedUsed to assess implications for flood risk Data management, visualisation, and stakeholder involvement usedFurther improvements to the overall method are being developed

ModelsDIVA: Dynamic and Interaction Vulnerability AssessmentProject: DINAS-Coast RegIS2 : Development of a metamodel tool for regional integrated climate change managementCOSMORamCo

Data SourcesIPCC Data Distribution CentreSea level dataPermanent service for mean sea levelGLOSS Global Sea-Level Observing System Remotely sensed dataLand Processes Distributed Active Archive Centre (NASA)Shuttle radar topography mission

GLOSS Tide Gauges

GTOPO30Global Digital Elevation Model

SRTM Data Morocco and Gibraltar (vertically exaggerated)

Data SourcesLocal observational dataSea level measurementsElevation/topography Wave recordingAerial photographyHabitat mapping

Concluding RemarksSea level rise could be a serious problem, but the uncertainties are largeImpacts are strongly influenced by human choiceReducing GHG emissions reduces but does not avoid sea level rise impactsPreparing to adapt would seem prudent, in the context of multiple stresses and managing existing problems

Full references can be found in Chapter 11, Bibliography, of the Handbook.

This point is expanded in slides 5 and 6.A proper analysis of socioeconomic vulnerability to sea level rise requires a prior understanding of how the natural system will be affected. Hence, analysis of coastal vulnerability starts with the natural system response. In addition, other climatic and nonclimatic stresses should be acknowledged in a vulnerability analysis, because sea level rise is not happening in a vacuum and coastal systems will evolve because of factors other than sea level rise. Hence, interacting climate and nonclimatic factors are included in this slide.

In addition to sea level rise, climate change could have a wide range of effects on coastal areas. The slide summarizes many of the potentially important factors, but also emphasizes the high uncertainties associated with some of the possible changes such as storminess that often attract the most concern. Because of these uncertainties, our understanding of the impacts listed in the table remains poorly developed compared to the effects of sea level rise, and cannot currently be considered in much detail.Global sea levels may rise between 20 cm and as much as 1 m in the coming century because of anthropogenic global warming. In addition, published models of future change underpredict historical sea level rise from 1880 to 1980 by about 1 mm/yr, so this discrepancy alone adds about 10 cm of uncertainty to future projections to 2100. Failure of the West Antarctic Ice Sheet could add a further 4 to 5 m of sea level rise, but the timing of the failure is currently unknown. Therefore, although we expect a rise in global sea level, its magnitude has a large uncertainty.

Mitigation policies to reduce or stop the growth of GHG concentrations in the atmosphere would slow, but not stop, climate change, even given stabilization of greenhouse forcing in the next few decades (which seems an optimistic goal). Therefore, there is a commitment to sea level rise, which suggests that some adaptation to sea level rise will be essential during the next century.

First sea level rise scenario predictions (1992) had a large uncertainty around the values, and this range has not been much reduced.

Thermal expansion and land ice changes were calculated using a simple climate model calibrated separately for each of seven AOGCMs (atmosphere-ocean general circulation models), and contributions from changes in permafrost, the effect of sediment deposition, and the long-term adjustment of the ice sheets to past climate change were added. Each of the six lines is the average of AOGCMs for each of the six (main) illustrative scenarios. The region in dark shading is the range of the average of AOGCMs for all 35 SRES scenarios (0.3 to 0.5 m). The region in light shading is the range of all AOGCMs for all 35 scenarios. The region delimited by the outermost lines is the range of all AOGCMs and scenarios, including uncertainty in land-ice changes, permafrost changes, and sediment deposition, giving a range of 0.09 to 0.88 m. Note that this range does not allow for uncertainty relating to ice-dynamical changes in the West Antarctic Ice Sheet.

Because of the large uncertainty surrounding the predictions, it is most appropriate to look across a range of scenarios such as no rise, 0.5 m and 1 m when assessing the impacts of sea level rise.Global sea level is controlled by climate, movements on the Earths surface, and rotation of the Earth and its effect on gravity. Climate influences the ocean water volume via changes in the density or to the total mass of the water. The density is reduced by thermal expansion as the ocean warms, and thermal expansion is expected to contribute the largest component to sea level rise over the next 100 years. Because of the large heat capacity of the ocean, thermal expansion will continue for many centuries after climate may have stabilized. Exchanges with water stored on land will alter the mass of the ocean. Groundwater extraction and impounded water in reservoirs have direct influence on sea level. And climate change is projected to reduce the amount of water frozen in glaciers and ice caps.On timescales of thousands to millions of years, the most important processes affecting sea level are those associated with the growth and decay of ice sheets through glacial-interglacial cycles, and this includes the response of the Earth to these changes. These are the glacio-hydroisostatic effects: the vertical land movements induced by varying surface loads of ice and water and by the redistribution of mass within the Earth and the oceans. Although major melting of the ice sheets ended about 6,000 years ago, the isostatic movements will continue.Earth or tectonic movement is the part of the vertical displacement of the crust not glacial, hydrological or isostatic origin. It includes rapid displacements from earthquakes and also slow events within and on the Earth (mantle convection and sediment transport). In coastal areas one of the consequences is the changing relationship between the land and sea surfaces as shorelines retreat or advance in response to the vertical land movements. At plate boundaries which are often continental or island margins, many of the worlds tide gauges are likely to contain both tectonic and glacio-eustatic signals. The gravitational effect of the rotation of the Earth is related to the changes in the Earths ice sheets, the consequences of which can affect the Earths rotation. These three processes combine with local changes related to meteorological, hydrological, and oceanographic processes, as well as local surface compaction and crustal movements, to produce a sea level change relative to the local land level. Ocean water volume (under climate in the previous slide) changes are controlled by the ocean temperature. Volume will increase because of melting of land-based ice contained within small glaciers (worldwide), but also more major ice sheets in Greenland and Antarctica (West Antarctic Ice Sheet).The human influence on the hydrological cycle can alter the volume of ocean, with increases in groundwater abstraction and impounded water in reservoirs. These factors add to uncertainty concerning future sea levels at the national and smaller scales relevant to vulnerability assessment. First, vertical land movements affect sea level. Relative sea level rise that is, the level of the sea in relation to that of the land rather than global sea level rise causes the effects of sea level rise. Land uplift will counter any global changes in sea level, whereas land subsidence will exacerbate global changes in sea level. Second, dynamic effects result from existing oceanic circulation, wind and pressure patterns, and ocean-water density differences, causing variations in the level of the sea surface with respect to the geoid that is, the surface of the ocean in the absence of oceanographic and meteorological dynamics. According to experiments using coupled ocean-atmosphere models, climate-change-induced changes to these processes could cause significant departures from the global mean change in sea level. Therefore, ocean dynamics add an additional component to relative sea level and further uncertainty to the magnitude of future change in relative sea level rise.

Local subsidence: Relative sea level rise observations are combined with IPCC relative sea level rise scenarios. The straight dashed line shows the observed trend during the 20th century. The rise during the 20th century (30 cm/century) is 10-20 cm/century larger than the global mean trend, reflecting the fact that New York is slowing subsiding (GIA). The relative middle scenario shows a twofold acceleration relative to the 20th century; however, the range is more than a threefold acceleration to a slight deceleration. Vertical land movement, or subsidence, is due to various geological processes such as tectonics, neotectonics, glacio-isostatic adjustment (GIA), and consolidation. During the 20th century, land movements due to GIA appear to have been comparable to global mean sea level rise. In addition to natural changes, groundwater abstraction and improved drainage have increased subsidence in many coastal lowlands, producing several meters of subsidence in susceptible areas over the 20th century, including several major cities.

Image on the left shows subsidence on the coast of Turkey following an earthquake in 1999.In addition to sea level rise, other aspects of climate are expected to change because of anthropogenic warming. Unlike sea level, however, the direction of that change is often uncertain. Sea-surface temperatures are certainly expected to rise, and on small islands, this will raise temperatures on the neighboring land areas. Many other changes of interest such as windiness or precipitation cannot be resolved within general circulation models (GCMs) at this point. The possible consequences of climate change on the tracks and intensity of tropical storms and hurricanes are very important. It is often stated that the frequency and intensity of tropical storms and hurricanes will increase and this gives great cause for societal concern. This could mean that the size of the hazards such as storm surges increases during a coastal storm. However, although the possible maximum storm intensity will increase in a globally warmed world, this does not answer the question about regional changes in storminess, which could see both increases or decreases.On August 29, 2005, Hurricane Katrina slammed into the southeast coast of Louisiana. The storm, which was as strong as Category 5, with winds up to 175 miles per hour (280 km/hr) and a central pressure of 26.75 inches (906 mbar) while in the Gulf of Mexico, weakened to a Category 3 shortly before it hit shore. The high winds and storm surge of up to 30 feet high (10 meters) caused massive damage in southeastern Louisiana, Mississippi, and Alabama. The levee system protecting the City of New Orleans collapsed, resulting in flooding of approximately 80% of the city. Total deaths from the storm are over 1,200 and damages and repair costs are estimated to be over $200 billion.The images are from the Red Cross (http://www.redcross.org/press/photo/katrina/35298.jpg) and NOAA (http://www.spc.noaa.gov/misc/carbin/katrina/kat5_1945.gif)Other impacts of climate change: A range of other effects of climate change will influence the coastal zone and exacerbate sea level rise impacts, including: rising sea water temperatures, a decline in sea ice, possible changes in frequency and intensity of coastal storms, more intense precipitation events, wave climate, and changes to levels of atmospheric CO2.Why are we concerned about sea level rise: (map shows Indo-China Peninsula).Many people live on low-lying coastlines. The effect of this has been in the news recently after the tsunami in Asia (26 December 2005), which chiefly affected populations on the low-lying coasts of Asia (although not the area shown in the maps above). Although the occurrence of tsunamis is not related to climate change, the effects may be exacerbated by an increase in sea level rise.

Source: Nicholls and Small, 2002.

Univariate distributions of population (bar graph) and integrated population density (IPD) (line graph) as functions of coastal proximity and elevation. IPD normalizes for differences in available land area by dividing the total number of people living at a given elevation or distance by the total land area at that elevation or distance. Note the lower densities in the lowest areas and those nearest the coast. In spite of this, the greatest concentration of population is at lower elevations near sea coasts. Source: Small and Nicholls, 2003.

The growth of coastal megacities (those with populations of more than 8 million people) is concentrating populations in hazardous places, particularly in developing countries. Twenty coastal megacities are predicted by 2010 (out of 30 megacities worldwide). The definition of a coastal megacity is based on the position of the city relative to the coast, including the likelihood that a 50 cm rise in sea level would have significant physical impacts within the city boundaries. (Seoul and Dhaka are not on the coast per se, but river levels within both cities would rise with sea level, increasing the risk of flooding. Larger, but more dispersed cities are omitted here, such as Hong Kong, Shenzen, and Guangzhou.) The growth of coastal megacities has been rapid and most of this growth is in developing countries.At least nine of the megacities are exposed to the threat of hurricanes or tropical storms. Given increasing sea surface temperatures, megacities such as New York and Tokyo at the higher latitude extent of hurricane storm tracks may be subject to an increasing frequency of destructive storms.Other issues are subsidence, drainage problems.Requirement for adaptation. Currently adaptation focused on preventing flooding (e.g. Tokyo, Osaka, Shanghai), but in the newer coastal megacities, future threat of global sea level rise is combined with existing hazards such as rapid subsidence, storm surge, and saltwater intrusion into water supplies.Source: Nicholls, 1995a.

Source: Nicholls, 1995b.National Vulnerability ProfilesNational Assessments: Susceptible coastal areas. Nineteen national vulnerability assessment studies are compared using a vulnerability profile for a 1 m sea level rise. The values for each of the classes (critical to low) should be interpreted in a relative rather than an absolute sense. The results show considerable variation in the degree of impacts from country to country, reflecting that certain settings are more vulnerable than others. Small islands (e.g. Seychelles), deltaic settings (e.g. Bangladesh), and coastal ecosystems appear particularly vulnerable. Number of people affected: Number of people living in the risk zone (coastal floodplain).People at risk: The average number of people who experience flooding by storm surge per year, including the benefits of sea defenses (with measures) Capital value at loss: Capital value of dry land and infrastructure that will be permanently lost by inundation or erosion due to sea level rise (expressed as a percentage of the national GNP).Land at loss: Area of land (dry and wetland) that will be permanently inundated or eroded due to a 1 m sea level rise.Wetland at loss: Natural area of coastal wetlands that will be lost or dramatically changed due to a sea level rise of 1 m.People affected: For Kiribati and Marshall Islands, 100% of the population.Land at loss: Marshall Islands, 80% of the national land area.Egypt: Increase in people at risk is because development scenarios are included (no development is considered for the other countries).Vulnerability classes used in vulnerability assessments. Annual protection/adaptation costs are calculated assuming total costs are incurred uniformly over 100 yr (taken from IPCC CZMS 1992); GNP: gross national product.Impact categories Vulnerability classesLowMediumHighCriticalPeople affected (no. of people/total population) x 100% 50%People at risk (no. of people x flood probability) / 1000< 1010-100100-500>500Capital value loss (total loss/1990 GNP) x 100% < 1 %1-3%3-10%>10%Land loss (area loss/total area) x 100% 30%Protection/adaption costs (annual cost/1990 GNP) x 100%1%Wetland loss (area loss/total area) x 100%30%Nile Delta: All deltas are low-lying and many are densely populated (common in Africa). They are subject to natural subsidence and hence experience a relative rise in sea level without any global rise. In general, human activity is reducing the sediment supply that has created and then sustained the subsiding delta surface. Subsurface fluid withdrawals (groundwater abstraction) enhance rates of subsidence. Based on present conditions, options to respond to sea level rise are limited and many populated deltas appear highly vulnerable to sea level rise. The population of Egypt is concentrated in the narrow strip along the banks of the Nile and across the fertile area of the delta, which is about 175 km long and 260 km wide. The average population density of Egypt is 62/km, but ranges from 2/km over 96% of the total area to 1,492/km in the Nile valley and delta. This area, where population density is among the highest in the world, is only 4% of the total area. Since the construction of the Aswan High Dam, the riverine floodplains and delta are no longer subject to annual flooding, and the Cyperus papyrus swamps of the wettest areas have largely disappeared. The remaining marshland is associated with lakes and lagoons along the seaward face of the delta. Outer margins of the delta are eroding, and salinity levels of some of the coastal lagoons are rising as their connection to the sea increases. If sea-water inundation occurs through climate change, densely inhabited areas of the delta would be affected, leading to the displacement of people and the loss of fertile land. Sea level rise is a particular threat to atolls (such as the outlying islands of the Syechelles); because of the lack of any available space, retreat to higher ground is not possible.

This also applies to many low-lying island states such as Tuvalu and Kiribati in the South Pacific and the Maldives (Indian Ocean). The biogeophysical effects of sea level rise will depend on the systems susceptibility (or sensitivity) to those effects, and its natural capacity to cope with these effects [resilience and resistance (adaptive capacity)]. Increased flooding could lead to permanent inundation of low-lying areas. Salinization is through saltwater intrusion.Increased loss of property and coastal habitats: Relocation of affected populations locally and globally, associated political, economical, institutional, and cultural stress of both the displaced population and the host countries. Increased flood risk and potential loss of life: Direct threats to human life, inundation, storm surgesDamage to coastal protection works and other infrastructure: Decline in land and housing property values. Threats to major infrastructure (including strategic harbors, coastal roads, railways). Threats to major coastal industry and services (including oil/petrochemical plants, pipelines).Loss of renewable and subsistence resources, including timber, livestock forage, recreation, water, and wildlife and fisheriesLoss of tourism, recreation, and transportation functions (ports, roads, railways).Impacts on agriculture and aquaculture through decline in soil and water quality: Threats to food production capacity, including decline in irrigation water quality, decline in coastal crop yields, and degradation/disappearance of crucial ecosystems such as mangroves, coral reefs, and coastal lagoons which act worldwide as fish and shellfish nurseries. Secondary impacts of accelerated sea level rise: Impacts on livelihoods and human health.Decline in health/living standards as a result of decline in drinking water quality, threat to housing quality, associated increasing health hazards linked to relocation, and spreading of disease vectors. Impacts on infrastructure and economic activity:Diversion of resources to adaptation responses to sea level rise impacts.Increasing protection costs, which may not be affordable to certain developing countries unless substantial aid is obtained. Increasing insurance premiums. Political and institutional instability, and social unrest.Threats to particular cultures and ways of life (e.g., in specific environments such as atolls where retreat to higher inland areas is not feasible).Source: Nicholls and Klein, 2005.The most appropriate timing for a response needs to be considered in terms of anticipatory versus reactive planned adaptation (in practical terms, what should be done now, versus wait and see?). Anticipatory decisions are made with more uncertainty than reactive decisions, which will have the benefit of future knowledge. But this wait and see may allow adverse development, increasing exposure to sea level rise.Diagram: Sea level rise has potential impacts. Anticipatory planned adaptation can reduce these potential impacts to the initial impacts. Reactive adaptation (including autonomous adaptation: takes place in response to climatic stimuli without intervention) in response to the initial impacts further reduces the effects of the residual impacts. The realistic magnitude of initial and residual impacts is a key measure of vulnerability (adaptive capacity).In the coastal zone, anticipatory adaptation needs to be carefully considered because many decisions at the coast have long-term implications. Examples of anticipatory adaptation in coastal zones include upgraded flood defenses and wastewater discharges, higher levels for reclamation and new bridges, and setbacks of buildings to prevent development in inappropriate areas.Whilst there is limited experience of adaptation to climate change, there is considerable experience of adapting to climate variability and this experience can be used to inform decision making under a changing climate. Adaptation to coastal problems is a process, rather than just the implementation of technical options. Given the commitment to sea level rise, the need for adaptation in coastal areas will continue for centuries, and this commitment to coastal adaptation needs to be built into long-term coastal management policy. This shows the linkages between the different adaptation approaches.

Proactive adaptation is aimed at reducing a systems vulnerability by either minimizing risk or maximizing adaptive capacity. Five generic objectives of proactive adaptation relevant to coastal zones are:1. Increasing robustness of infrastructural designs and long-term investments2. Increasing flexibility of vulnerable managed systems3. Enhancing adaptability of vulnerable natural systems4. Reversing maladaptive trends5. Improving societal awareness and preparedness.

For coastal zones another classification of three basic adaptation strategies is often used:Protect Reduce the risk of an event by decreasing the probability of its occurrence.Accommodate Increase societys ability to cope with the effects of the event.Retreat Reduce the risk of the event by limiting its potential effects.Each of these strategies are designed to protect human use of the coastal zone and, if applied appropriately, they each have different consequences for coastal ecosystems. Retreat and accommodation avoid coastal squeeze because onshore migration of coastal ecosystems is not hindered. In contrast, protection will lead to a coastal squeeze, although this can be minimized using soft approaches to defense, such as beach nourishment. Accommodate and retreat are best implemented proactively, whereas protect can be either reactive or proactive.Source: Nicholls and Klein, 2005.

The most recent shoreline management guidelines used in England and Wales are applied at a national level and may be adapted for use elsewhere. They are a set of proactive strategies for shoreline management, which will be implemented in Shoreline Management Plans.

Reversing maladaptive trends and improving societal awareness and preparedness are not explicitly addressed in the Defra guidelines. Managed realignment can be seen as reversing maladaptive trends in historical land use. And these approaches are addressed in other aspects of government shoreline management policy. Project appraisal methods are now based on cost-benefit analysis, whilst flood warnings are a central element of flood management in England and Wales.

The option of accommodation is not addressed, however, except in relation to warning systems. This is generally the case in Europe, which contrasts with that of the United States, which uses accommodation extensively, for example, building coastal buildings above the levels of surges and waves on pilings.There are a variety of methods of adaptation within the three IPCC categories of retreat, accommodation, and protect.Under the CPACC (Caribbean Planning for Adaptation to Climate Change) project, Antigua Barbuda SIDS (Small Island Developing State) carried out an study and produced a report, Formulation of a Policy Framework for Integrated Adaptation Planning and Management.There is a lack of adequate resources for adaptation.Very low-lying, 70% of Antigua is less than 30 m above sea level, and more than 60% of the population live in the coastal zone. Reclamation of land, sand mining, and lack of comprehensive natural system engineering approaches to control flooding and sedimentation have increased the vulnerability to erosion, coastal flooding and storm damage. The number and intensity of tropical storms have increased over the last 10-15 years.Changes in rainfall are likely to produce conditions of drought and flood over time.

Under the CPACC (Caribbean Planning for Adaptation to Climate Change) project Antigua carried out an study and produced a report, Formulation of a Policy Framework for Integrated Adaptation Planning and Management. The Antigua report included data collation of information relevant to climate change, such as beach erosion rates, hurricane/storm activity, coral reef condition surveys, biodiversity surveys, water resources, socioeconomics (population, demographics, tourism, economics).The potential impacts identified included: Property/infrastructure: Especially in low-lying coastal areas, which can lead to changes in employment structure of the country.Coastal and marine ecosystems: Increased destruction and loss of coral reefs, sea grass beds, beaches and mangroves.Destruction of hotels and other tourism facilities, and psychological effects of potential visitors.Disease: Increased incidence of vectors, increased risk of various infectious diseases, increased mental and physical stress etc from hurricane activity. Also public and environmental health consequences.Fisheries: Damage and loss to fisheries equipment, vessels and infrastructure from storm and hurricane activity.The report identifies adaptation approaches for Antigua and Barbuda within the three generic adaptation measures of retreat, accommodate, and protect.

The first stage is to develop sea level scenarios, which could involve downscaling of global scenarios to the regional or local level. This is not explicitly discussed here. It is often best, however, to use a range of sea level rise scenarios. Uncertainties in sea level rise predictions create a need to assess a range of scenarios within vulnerability assessment. These scenarios need to embrace the range of likely change.The aim of both screening assessment and vulnerability assessment is to focus attention on critical issues concerning the coastal zone, rather than to supply precise predictions.Planning assessment of different responses to sea level rise within ICZM is part of a continuous management process that ideally aims to integrate responses to all existing and potential problems of coastal zone, including minimizing vulnerability to long-term effects of climate change.

As a first step a screening assessment should be undertaken using existing data that will highlight possible impacts of a 1-m rise in sea level as well as key data gaps. It aims only to identify susceptibility with limited consideration of possible responses. These results will enable a subsequent more comprehensive vulnerability assessment. This is a more comprehensive analysis, including a preliminary assessment of the ability of society to respond to the projected changes.

The existing data are often scattered, and compiling all the information described shown here can be a considerable effort. Further, some of these data will not be available. However, once assembled, a coastal database provides a basis for more informed decisions and helps to identify critical data gaps.

Sources of some of these data to be discussed later.The relative importance of impacts will vary from site to site, depending on a range of factors.(1) Increased storm flooding. (a) Describe what is located in flood-prone areas. (b) Describe historical floods, including location, magnitude and damage, the response of the local people, and the response of government. How have policies toward flooding evolved?.(2) Beach/bluff erosion.(a) Describe what is located within 300 m of the ocean coast.(b) Describe beach types.(c) Describe the various livelihoods of the people living in coastal areas such as commercial fishers, international-based coastal tourism, or subsistence lifestyles.(d) Describe any existing problems of beach erosion including quantitative data. These areas will experience more rapid erosion given accelerated sea level rise.(e) For important beach areas, conduct a Bruun rule analysis (Nicholls, 1998) to assess the potential for shoreline recession given a 1 m rise in sea level. What existing coastal infrastructure might be impacted by such recession?(3) Wetland and mangrove inundation and loss. (a) Describe the wetland areas, including human activities and resources that depend on the wetlands. For instance, are mangroves being cut and used, or do fisheries depend on wetlands?(b) Have wetlands or mangroves being reclaimed for other uses, and is this likely to continue?(c) Are these wetlands viewed as a valuable resource for coastal fisheries and hunting or merely thought of as wastelands?(4) Salt water intrusion.(a)Is there any existing problem with water supply for drinking purposes?(b) Does it seem likely that salinization due to sea level rise will be a problem for surface and/or subsurface water?

The implications of any future planned developments on the coastal zone should be considered, and how any future development might affect vulnerability to sea level rise. In many parts of the world significant coastal development is expected in the next few decades. Issues to consider include (1) new (and existing) river dams and their impact on downstream deltas, (2) new coastal settlements, (3) expansion of coastal tourism, and (4) the possibility of transmigration.

Once the sea level rise impacts are identified and their magnitude assessed, what are realistic responses to these problems? Three generic responses (planned) retreat, accommodate, and protect have been defined and might usefully be considered in the analysis.Conduct an informal survey of how other people in positions of influence in the country would respond to the problems of sea level rise. Explain property ownership laws in your country. Can the government tell people that they must retreat as the water begins to threaten them? Will or can people stay in place and just build the houses higher for safety and risk reduction? Describe the history of coastal protection in the country and what this might indicate about future responses to sea level rise (a) beach fill, (b) bulkheads, (c) seawalls, (d) groins, and (e) drainage of storm water/sewage runoff.

This matrix (SAM) can be used to organized the screening assessment exercise. The SAM should be generated along the coastline. For example, one could be produced for each of the coastal geomorphology classes or other types of coastal classification (political jurisdiction). It could also include more contemporary issues such as beach mining and the construction of harbors.

Ideally, impact assessment should consider all biophysical and socioeconomic impacts, but in practice the objectives of any impact assessment study for an activity or project should reflect the time and resources available. Hence, it is important at an early stage to rank the relative importance of potential impacts as (1) not relevant, (2) low, (3) medium, or (4) high, together with relevant comments, in a form such as this table. If change factors other than sea level rise are considered, the process needs to be repeated with those factors. In each case, this could be the outcome of a screening assessment as already discussed.The resulting matrix is useful to focus resources on the major potential impacts. It is also illuminating if a ranking is not possible or problematic, because this would suggest that a broad, but general assessment is necessary, with a goal of achieving such a ranking in subsequent analysis.

It is important to have a conceptual framework within which ask basic questions about impacts and vulnerability. In practical terms, it is unlikely that all these systems properties will be fully assessed in a VA. However, this model offers a goal of what a comprehensive VA could try and quantify.

The ultimate goal of vulnerability assessment is to produce recommendations on actions to reduce vulnerability. It includes the assessment of both anticipated impacts and available adaptation options. A simple impact assessment might not consider adaptation options to facilitate rapid analysis, but any comprehensive impact assessment must consider adaptation options, as adaptation potential will influence the magnitude of the actual impacts.First, it distinguishes between the natural-system vulnerability and the socioeconomic-system vulnerability to climate change, even though they are clearly related and interdependent. Second, a proper analysis of socioeconomic vulnerability to sea level rise requires a prior understanding of how the natural system will be affected. Hence, analysis of coastal vulnerability always starts with the natural system response. Lastly, other climatic and nonclimatic stresses are acknowledged, indicating that sea level rise is not happening in a vacuum and that the coastal system will evolve due to factors other than sea level rise.

Looking to the natural system, the biogeophysical effects of sea level rise will depend on the systems susceptibility (or sensitivity) to those effects and its natural capacity to cope with these effects (resilience and resistance). Susceptibility simply reflects the coastal systems potential to be affected by sea level rise (e.g., a low-lying, erodible coast versus a cliffed, unerodible coast), whereas resilience and resistance describe the natural systems stability in the face of perturbation. Resistance describes the ability of the system to avoid perturbation, and resilience describes the speed with which a system returns to its original state after being perturbed. Susceptibility, resilience, and resistance collectively determine the coastal systems natural vulnerability to the biogeophysical effects of sea level rise. Resilience and resistance are functions of the natural systems capacity for autonomous adaptation, which represents the coastal system's natural adaptive response to sea level rise (e.g., if sea levels rise, then wetlands respond by accreting upward more rapidly, which might stop the inundation). As opposed to susceptibility, which is largely independent of human activities, resilience and resistance are often sensitive to human activities. Human influence often has negative consequences, but in contrast, planned adaptation can serve to reduce the natural vulnerability by enhancing the systems resilience and/or resistance and thereby enhancing the effectiveness of autonomous adaptation.Source: Klein and Nicholls (1999).

Co-evolving coastline: It is important to acknowledge the potential for dynamic interaction between the natural and socioeconomic systems. Instead of being considered as two separate systems that exist independently of each other, natural and socioeconomic systems are increasingly being viewed as developing in a coevolutionary manner, although the extent of this interaction under different circumstances remains to be quantified. Historically the physical situation has driven the socioeconomic state; however, in the future it is more likely that socioeconomic will drive the physical nature and condition of the coastline.

The experience of all these methodologies shows that there are still barriers to conducting comprehensive impact and response analyses because of a number of factors.These issues will not be overcome rapidly, although significant progress can be made simply by recognizing these shortcomings and hence having realistic expectations of vulnerability assessments. There are a number of different assessment tools.This slide is a schematic representation of the mechanisms steering the location of the upper shoreface. Sediment exchanges differentiate sediment fluxes into sand and mud fractions. A represents exchange between the backbarrier and upper shoreface (either bypassing of sand from the shoreface to the lagoon behind the barrier or net supply of sediment to the overall coastal sediment budget). B is the lower shoreface coupling, which involves long-term adjustments, tending to steer the upper shoreface in a landward or seaward direction, depending on whether evolution of the lower shoreface causes it to act as a net sink or source for sand-sized sediments. For short-term (subdecadal) prediction of horizontal movements in the upper shoreface, sand exchanges with the lower shoreface are usually ignored because the fluxes are so small that resulting morphological change is negligible (i.e. closure depth concept) (B). The fluxes of fine sediments (C and D) are not directly relevant to the upper shoreface sediment budget and mud deposition therefore is negligible. C is a direct coupling between the lagoon and lower shoreface, due to the possibility that fine sediments (discharged at delta) bypass through the tidal inlet and upper shoreface to settle out of suspension on the lower shelf surface as mud deposits. Upon resuspension on the lower shoreface these sediments may be transported back into the lagoons. Mud deposited in the lagoon reduces the rate of long-term recession of the upper shoreface. For long-term predictions, none of the internal sediment exchanges can be ignored, because systematic sediment fluxes that are small on the subdecadal time scale eventually accumulate through time to produce measurable morphological changes. Moreover the changes in the morphology of the backbarrier, lower shoreface, and upper shoreface cause these three zones to interact dynamically. The backbarrier is a morphological complex that can include dunes, estuaries (or tidal lagoons), fluvial deltas, and coastal lowlands formed as lagoons become sediment filled. The upper shoreface is a morphological complex that can incorporate river and ebb-tide deltas as well as surf zone morphologies.The littoral cell defines the alongshore extent of the coastal tract. Natural boundaries of the cell may coincide with points of convergence, divergence, or topographic barriers in the littoral transport system. Or the littoral cell may be of arbitrary extent depending on the site specific problem. The cell need not be closed to alongshore sediment transport but net gains and losses of sediments across cell boundaries must be estimated.Source: Cowell et al., 2003.

Seventy percent of worlds sandy beaches lost to erosion.Introducing the use of the Bruun Rule, its limitations, and when it can be applied. (The Bruun Rule can be applied at any level of assessment: the screening assessment uses a rule-of-thumb Bruun Rule, vulnerability assessment uses the full Bruun Rule, and planning assessment requires a complete sediment budget of the coastal zone.)

Assessing erosion involves using the Bruun Rule for straight areas of coastline. The assumption is that the profile conserves its average or equilibrium shape relative to sea level. Using appropriate boundary conditions, the profile shape defines all the information necessary to predict the response to sea level rise. To maintain the profile shape the upper part of the profile erodes and the lower part of the profile accretes, translating the shoreline landward. Source: Nicholls, 1998.

G represents the grain size of eroded material i.e. material that is too fine for the beach is lost, increasing the predicted erosion, or the proportion of sediment eroded that is sufficiently coarse to remain within the equilibrium beach profile.

The inverse of the beach slope (L/H) multiplies any sea level rise, giving a large recession for a small rise in sea level. Therefore flatter beaches are predicted to show greater sensitivity to sea level rise than steeper beaches. Source: Nicholls, 1998.

Sea level does not change the shape of the profile, it only creates a potential for erosion, which the availability of wave energy realizes. Therefore profile adjustment to higher mean sea levels is expected to take time. The major implication of this is that the Bruun Rule is best applied over long timescales (decades to centuries).

Also other processes will also cause the beach morphology to change. At coasts with inlets, the so-called Indirect effect of sea level rise can be important where the tidal basin or lagoon acts as a sediment trap as sea levels rise. This sediment is derived from the open coast causing erosion which locally can be 10 times the magnitude of the Bruun (or direct effect of sea level rise). This effect is limited to 10 to 20 km from the inlet.

In addition to climate change, gradients in longshore transport will also often cause additional erosion or accretion, and shoreline position also varies due to climatic variability (eroding during storms and recovering afterwards).

Hence, any predictions of shoreline recession need careful interpretation.

For more details see the recent review of Stive (2004).

The second vulnerability assessment area is erosion, flooding, and impact on wetlands. Climate change and sea level rise are likely to cause an increase in flood levels, increasing the likelihood of flooding. This is combined with a projected increase in populations in the coastal floodplain. There is a requirement for adaptation in the coastal zone to address the flood risk, and examples of adaptation are an increase in flood protection and an increase or change in the approach to management and planning in the floodplain.Sea level rise will cause an increase in the level of the hazard zones. This means that an area that is now subject to a 1 in 100 year flood risk may in time become subject to a 1 in 10 year flood risk, and the landward boundary of the coastal flood plain will move inland over time. This has implications for the locations of settlements and for the calculation of risk to populations. Assuming evolving protection, the number of average annual people flooded first increases to 27 million in the 2050s and then decreases to 13 million people in the 2080s [i.e., rising standard of flood protection becomes more important than population increase (and subsidence) after the 2050s]. This different behavior shows the importance of considering the changes that might occur without any specific adaptation for sea level rise.

Source: Nicholls et al., 1999.

Source: Nicholls et al., 1999.The slide shows regional implications of sea level rise, illustrating the regions most affected by flood impacts given the HadCM2 (mean) scenario for the 2080s. [HadCM2 (mean) scenario: GHG only ensemble experiment, general circulation model experiment of the Hadley Centre, predicted global sea level rise of about 38cm from 1990 to 2080s. The climate forcing assumes a growth in CO2 concentrations from 354ppmv (in 1990) to 731ppmv (2080s).]Globally about 200 million people lived in the coastal floodplain (below the 1 in 1000 year surge-flood elevation) in 1990, or about 4% of the worlds population. It is estimated that on average 10 million people a year experience flooding. Even without sea level rise this number will increase significantly due to increasing coastal populations. The most vulnerable regions in relative terms are the island regions of the Caribbean and Indian Ocean and Pacific Ocean small islands. The absolute increases are largest in southern Asia, Southeast Asia, and the coast of Africa. The slide shows that for a midlevel estimate of sea level rise (45 cm) by the 2080s on the coast of Africa, up to 10 million people per region (West Africa, East Africa, and the southern Mediterranean) will be at risk from flooding each year. The worst case predicted is for southern Asia, where more than 50 million people could be at risk from flooding each year by the 2080s. Source: Nicholls and Wilson, 2001.Results from the RegIS project (Regional Climate Change Impact and Response Studies in East Anglia and North West England), for the East of England, United Kingdom, represented on a 5 km grid. The impacts of flooding were modeled with no adaptation taken into account. The low climate change scenario assumes a sea level rise of 16 cm and an increase in peak river flow of 5%, and the high climate scenario assumes 71 cm and an increase in peak river flow of 20%. From the reference state, taken from a land use map showing the situation in 1990, the changes in the amount of land unsuitable for arable farming are shown for both scenarios in the 2050s. Sea level rise causes the existing floodplain to be flooded more frequently and an expansion of the flooded area.Land with a flood defense standard of protection of less than or equal to 1 in 10 years (10% probability of exceedence in a year) is assumed to be unsuitable for arable farming.Source: Parry et al., 1998b.

This graph shows the effects of mitigation on the numbers of people predicted to be affected by coastal flooding each year. The warming currently expected by 2050 without any deliberate mitigation is estimated to be 1.4C. The full implementation of the Kyoto Protocol targets will reduce this only slightly. Assuming no climate change the number of people living in the coastal zone is expected to rise to 500 million by 2050, and the number of people experiencing coastal flooding each year will increase to 27 million without taking into account sea level rise (blue bar). Under the unmitigated emissions scenario an extra 23 million people could be affected by flooding each year (50 million total; red bar). The Kyoto target only reduces this by 1 million and a 30% emissions reduction only decreases the people affected by 3 million (47 million total). This means that mitigation alone cannot prevent the impact of sea level rise on coastal areas, adaptation will be necessary. Source: Nicholls and Small, 2002.The Thames Barrier currently forms the major part of the tidal defenses protecting London. Construction of the barrier started in 1972 and it became operational in 1982, at a cost of 535 million (1300 million at 2001 prices), although this cost does include associated defenses to prevent floods circumnavigating the barrier. The barrier stretches 520 m from bank to bank of the river Thames. It is operated by giant hydraulic power packs housed in huge stainless steel shells. These hydraulics raise and lower massive gates that stem the water flow to protect central London from the risk of flooding. When not in use the gates rest on the riverbed. A severe flood in London could paralyze the central part of the London Underground, cause damage to fresh water and sewer systems, and disrupt power, gas, telephone and vital data services.Thousands of homes, shops, factories, businesses, and buildings would be affected. It could take months to get London functioning again.The financial cost of a major flood could be enormous, probably topping 30,000 m, without counting the cost in human suffering and potential loss of life.It currently protects London to a standard of 1 in 1,000 years; however, with climate change it is estimated that the level of flood protection will no longer be adequate for the city of London past 2030. A major study is currently assessing the options of enhancing the barrier and other defenses, including the possible construction of another barrier farther downstream, to protect the city of London past 2100.

In the UK this is only form of adaptation, others include shoreline management planning, flood defense government policy, flood warning systems and efforts to increase public awareness. A range of parameters can be used to describe exposure and the risk of flooding. Here the coastal population is used as an input to derive two impact parameters.People in the hazard zone the number of people living below the 1000 year storm surge elevation (i.e. the exposed population ignoring sea defenses).Average annual people flooded: the average number of people who experience flooding by storm surge per year, including the benefits of sea defenses (also referred to as people at risk).People to Respond: the average number of people who experience flooding by storm surge more than once per year. Estimates of the storm surge elevations are raised over time by the relative sea level rise scenario (i.e., global rise plus estimated subsidence) and converted to the corresponding land areas threatened by these different probability floods. These areas are then converted to people in the hazard zone using the average population density for the coastal area. Lastly the standard of protection offered by defenses (i.e., the estimated level of flood risk) is used to calculate the average annual people flooded.The third of the vulnerability assessment areas, ecosystem loss, involves an analysis of the inundation and displacement of wetlands such as mangroves and saltmarshes. It does not consider coral reefs.

Wetland areas are important because they provide flood protection; they also are important nursery areas for juvenile fish and often fish species that are important for fisheries and therefore for the local economy. Wetlands are important for nature conservation because of the diversity of species present. The loss of wetland area can result in a loss of valuable resources, including the possible use of the area for tourism.Wetlands are sensitive to sea level rise because their location is intimately linked to sea level. Wetlands are not passive elements of the landscape, however, and their vertical response shows a dynamic and nonlinear response to sea level rise. Therefore losses will occur only above some threshold rate of rise. The available evidence shows that wetlands experiencing a small tidal range are more vulnerable to relative sea level rise than those experiencing a large tidal range. Direct losses of coastal wetland due to sea level rise can be offset by inland wetland migration (dryland conversion to wetland). As sea level rises, so low-lying areas adjacent to wetlands may become suitable for growth of wetland plants. In areas without low-lying coastal areas, or in areas that are protected to stop coastal flooding, wetland migration cannot occur, causing what is termed coastal squeeze.

The presence of hard coastal defenses causes coastal squeeze of wetlands such as mangroves and saltmarsh. As sea level rises, the habitat should accrete vertically and migrate landward (a); if hard defenses are present (b) this is not possible and the habitat will become smaller over time and eventually not viable. In tropical and subtropical regions the major wetland at risk from coastal flooding is the mangrove. It is an easily recognized habitat found on coastlines and in brackish estuaries and deltas, and is made up of evergreen shrubs and trees growing on tidal mud and sand flats. The plant community is known as a mangal or mangrove and is typically a forest with a dense canopy. Although they occur along approximately 2/3 of all saline tropical coastlines, mangroves are a very linear feature and as such as are fairly vulnerable.These areas are highly productive and should be valued as very important as nursery grounds for fish and molluscs. They also serve as excellent sediment sinks and protect the coastline from waves.The ability of mangroves to adapt to rising sea level will depend on their ability to move inland or to accrete vertically. Like other coastal wetlands, mangroves can move inland only if there is land available, but the land area behind mangroves is commonly the most developed area in the tropics. Areas most vulnerable to coastal wetland loss: the regional implications of sea level rise: the regions in red are those where wetland losses may exceed 65% under the HadCM2 (mean) scenario by the 2080s, where the losses are those caused by sea level rise, as opposed to other reasons. These wetlands are vulnerable primarily because of the low tidal range in these areas. By the 2080s most of the wetlands around the Mediterranean could be lost.

Source: Nicholls and Wilson, 2001.This slide show results from the RegIS project (Regional Climate Change Impact and Response Studies in East Anglia and North West England), for the east of England, United Kingdom, represented on a 5 km grid. The impacts of sea level rise on coastal wetlands were modeled. The low climate change scenario assumes a sea level rise of 16 cm, and the high climate scenario assumes 71 cm. Saltmarshes respond to sea level rise by accreting vertically as they are submerged for longer periods of time and by migrating inland if there is space. So, saltmarshes are drowned only if the rate of sea level rise exceeds their accretion potential. In Britain inland migration is nearly always prevented by flood defenses, so it can happen only if defenses are abandoned or removed.To measure the response the vertical accretion potential was compared to sea level rise. Saltmarshes in coastal areas that have a small tidal range are more susceptible to sea level rise than those in similar areas with a large tidal range. The capacity for saltmarshes to respond to sea level rise is therefore parameterized as a function of the rate of sea level rise divided by tidal range, giving a normalized rate of sea level rise. This is used with a critical value of sea level rise derived from the literature to determine the saltmarsh response to rising sea levels (the critical value is related to sediment availability). Above the critical rate, losses of saltmarsh are assumed to occur linearly. The method is not specific about which part of the saltmarsh is lost only a proportional loss is determined.Saltmarshes are already being lost from the coastal area to the south, and this is exacerbated by sea level rise; under low climate change the area experiencing loss increases. Under high climate change the amount of loss in existing areas increases and the areas experiencing loss increase up onto the Norfolk coast, where the sea level rise now exceeds the critical value and the saltmarsh has begun to erode. The modeling is split into an assessment of the two dimensions of the wetland system response: Vertical acretion and wetland migration.Vertical accretion is based on the rate of relative sea level rise. Sea level rise triggers coastal wetland loss when the rate of sea level rise exceeds a defined threshold, taking into account any system lags.Ideally there should be available site-specific information on the potential for vertical accretion and landward migration for each wetland site, including factors such as sediment availability. Unfortunately this is not available, so we use this aggregated approach.To model vertical accretion, a generalized threshold approach is used (described in the next slide). The availability of sediment/biomass is parameterized using critical values of the RSLR* parameter. A critical value of RSLR* (RSLR*crit) distinguishes the onset of loss due to sea level rise, i.e., only inundated above a certain threshold rate of rise. The threshold rate is site specific and depends on a combination of sediment availability and biomass production and preservation. If wetland loss is predicted it is modeled linearly as a function of RSLR*. This simple model captures the nonlinear response of wetland systems to sea level rise and the association of increasing tidal range with lower losses. Based on available literature RSLR*crit was assumed to range from 0.18 to 0.5.The response of a wetland to long-term sea level rise is not instantaneous and, based on geomorphic calculations, a 30 year time lag can be applied. To model horizontal response, migratory potential can be assessed using the global coastal typology of Valentin (1954). In areas where wetland migration is possible, wetland losses are assumed to be zero (i.e., wetland migration compensates for any losses due to inundation). It is uncertain to what extent wetlands in deltaic and barrier areas might migrate inland. Therefore losses can be calculated assuming both migration, and no migration, and this contributes to the range of the results. Additionally, if the population density exceeds 10 inhabitants/km2 it can be assumed that wetland migration will be prevented. Owing to the large, growing population around most of the worlds coasts, the potential for wetland migration is considerably reduced compared to the situation in earlier geological periods of rapid sea level rise.In addition to the effects of sea level rise on coastal wetlands, an appropriate baseline for loss must be considered. 1% per year is the present rate of loss, 0.4% per year, represents immediate moves to more effective conservation and 0.4% per year from 1990 to 2020, followed by zero loss, implying that all losses are compensated by habitat recreation.Other climate change impacts, including changing storm frequency or direction and changing sediment supply, must be considered. If future problems of beach erosion are to be managed, a comprehensive understanding of the sediment budget will be essential.Example planning assessment, from the UK. This slide shows an area of cliff protection and groins (beach stabilization), showing a healthy beach system.Source: Tyndall Centre for Climate Change Research.

This slide shows downdrift, an eroding area of cliff, where the cliff protection is falling into disrepair and the area is currently experiencing very high rates of cliff erosion. This means that there has been loss of properties at the cliff edge; this is likely to continue and possibly get worse over time.

Source: Tyndall Centre for Climate Change ResearchThe aim of the planning assessment is specific to the area, focusing on the issues that are important. Here there are conflicting issues of cliff retreat causing loss of housing and development, but the erosion of the cliffs provides sediment through longshore drift to areas downdrift, sustaining the beaches. The land behind the downdrift beaches is low-lying and subject to a high flood risk, exacerbated by any depletion in the beach volume. This complex situation calls for an integrated flood and erosion assessment. The planning assessment includes future assessment of beach evolution; the maintenance and upgrade/degradation of flood and coastal defenses; socioeconomic changes such as patterns of development; sea level rise scenarios; and changing patterns of storminess.

Source: Tyndall Center for Climate Change Research.Source: Tyndall Centre for Climate Change Research

Source: Tyndall Center for Climate Change Research

The scenarios used cover physical factors, i.e., climate change and sea level rise, and also socioeconomic specific scenarios covering spatial development patterns, types of development (industrial or residential), transport and infrastructure development, and also the levels and types of coastal and flood protection that will be afforded in the future.These scenarios feed into two types of models, the regional wave and surge models, and the regional morphological model, SCAPE. SCAPE predicts the amount of cliff erosion under the conditions depicted by the scenarios and the influences of this on sediment budgets and therefore the likely morphology of areas downdrift. This information feeds into a flood risk model. This is a 2D hydraulic model predicting flood inundation over the coastal floodplain. This combines with the results of the cliff erosion analysis (recession of cliff top and cliff toe) to produce an integrated sediment cell-scale assessment. Models used within the planning assessment:

The regional wave and surge modeling uses bathymetry (elevation/topography of the sea bed) to transform offshore wind and wave measurements into the nearshore zone, predicting the wave conditions that are experienced at the coast. This modelling technique is used because measuring the wave conditions along the coast at individual points for sufficient periods of time would be expensive and the data are not generally available. Offshore wave measurements have been collected for a number of years, however, using navigation buoys, offshore oil and gas platforms, etc., as bases.

Source: Tyndall Centre for Climate Change Research.Sources: Walkden and Hall, 2005; University of Newcastle; Tyndall Centre for Climate Change Research.

SCAPE Model: The SCAPE model uses the inshore waves (outputs of the wave model) to predict the cross-shore erosion, the cross-shore shape, and from that the cliff retreat and beach volume. The cross-shore shape is that for Section n. The beach volume and the inshore waves results are used to predict the longshore sediment transport and this interacts with the modeling repeated using inputs for a location a set distance along the shore in a downdrift direction to produce Sections n+1. The cross-shore shapes of Sections n and n+1 are added to produce a Q3D shore shape. This is repeated for progressive timesteps, using the results of each to feed into the next for each section and also using the appropriate wave transformation data.

Sources: Walkden and Hall, 2005; University of Newcastle; Tyndall Centre for Climate Change Research.

The model runs were carried out using different protection scenarios for the cliffed area. At present there are defenses in place for the settlements along the cliffed section of coast and under this scenario these defenses are maintained in situ. The current government policy in England is for defenses to be built to accommodate a 6 mm/year sea level rise over the next 100 years, and this is the rate of rise that has been modeled. The graph on the right shows the amount of recession over the 50 year time period in 5 year steps. Between the protected settlements the erosion reaches up to 50 m at a rate of almost 1 m a year in the northernmost areas.

Sources: Walkden and Hall, 2005; University of Newcastle; Tyndall Centre for Climate Change Research.

The modeling was repeated for the same area, timescale, and 6 mm/yr sea level rise, but with two different policies applied to the defenses. Do nothing implies that the defenses in place now are left in situ but are literally abandoned and no maintenance is performed. Open coast implies that the defenses currently in place are removed at the beginning of the model runs. For both situations the settlements where defenses were originally protecting the cliffs from erosion experience a massive increase in the amount and rate of erosion and retreat. This is because the coast and cliffs are currently out of equilibrium and as the coast attempts to realign to a more natural configuration the response is much faster. Rates of over 2 m/year are experienced under this modeling scenario. Between the settlements erosion still continues at much the same rate as per the previous policy of maintained defenses.

Sources: Walkden and Hall, 2005; University of Newcastle.

The increased rates of erosion and retreat at the location of previously protected areas are clearly seen in this comparison.

Sources: Koukoulas et al. 2005; University of Southampton.

The SCAPE GIS mentioned in the methodology is very useful for visualizing the modeled data. This shows the town of Cromer and the retreat of the cliff toe/base in 10 year time steps. Overlain onto a digital elevation model, this clearly shows the consequences of the abandonment of the defenses for the town. Summary of three levels of assessment:Initial screening assessmentMore in depth vulnerability assessmentSite-specific in depth planning assessment, with high demands on data and time. DIVA is available at www.dinas-coast.netwww.silsoe.cranfield.ac.uk/iwe/projects/regis/regis2.htm

Demo versions of COSMO and RamCo (more information on the UNFCCC website) can be downloaded from the www.netcoast.nl website. www.netcoast.nl/tools/cosmo.htm and www.netcoast.nl/tools/ramco.htm

COSMO: main steps in the preparation, analysis, and evaluation of CZM plans; it allows the coastal zone managers to explore the impacts of development projects and environmental and coastal protection measures, including the long-term effects of climate change.

DIVA: From the project DINAS-Coast: Dynamic and Interactive Assessment of National, Regional and Global Vulnerability of Coastal Zones to Climate Change and Sea Level Rise. DIVA stands for Dynamic Interactive Vulnerability Assessment, and is the assessment tool, comprising four parts:1) A detailed global database with biophysical and socioeconomic coastal data2) Global and regionalized climate and socioeconomic scenarios until the 25003) An integrated model allowing interaction between modules that assess biophysical and socioeconomic impacts and the potential effects and costs of adaptation4) A graphical user interface for selecting data and scenarios, running model simulations and analysing the results. The aim of the tool is for the end user to assess coastal vulnerability to global sea level rise. Information produced within DIVA enables users to: 1) Explore the effects of climate change on coastal environments and societies2) Explore the costs and benefits of coastal adaptation options3) Use the results for further scientific and policy analysis.However, DIVA should be used to carry out trial runs and explore broad coastal adaptation strategies. The regional resolution of DIVA does not support analysis for operational coastal management and planning (the coastal segment length is on average 70 km); this would require a more detailed scale approach.DIVA was designed specifically to be accessible to a broad community of users, and therefore the aim is to produce a user-friendly graphical interface and a computationally efficient (i.e., fast) model. The modules contained within the DIVA model are:- Relative sea level rise- River effect- Indirect erosion- Total erosion- Wetland change- Flooding- Wetland valuation- Tourism- World heritage sites- Costing and adaptationThe flooding module shifts surge elevations upwards by relative sea level rise. The wetland change module captures the integrated response of wetlands to sea level rise. RegIS2: The RegIS2 project: Development of a metamodel tool for regional integrated climate change management. Funded by Defra (UK Government) (2003-2005). Objectives of the project: - To enable stakeholders to assess for themselves the impacts of future climate change on the agriculture, biodiversity, hydrology, and coasts of two regions of England (East Anglia and North West)- To explore the impacts for the 2050s- To involve regional experts, decision-makers, and other stakeholders throughout the assessment- To develop, calibrate, and validate metamodels (or simpler models) based on simulations using existing impact models, which can be used to assess the impacts of climate change- To develop a robust and user friendly software tool for stakeholders to analyze climate change impacts, their interactions, and adaptive responses using the metamodels- To analyze the range of possible adaptive responses and the influence of future policy and socioeconomic scenarios on the response- To work with stakeholders to communicate the findings to the appropriate policy and lay audiences.The impact assessment will be conducted with the help of simple or metamodels developed from a range of pre-existing models, which will be adapted so that they are appropriate for the specific conditions existing in East Anglia and the North West. The key models to be used as the basis for the metamodels are listed below:Agriculture and Land Use: IMPEL (Integrated Model to Predict European Land Use) simulates the dynamics of land use by combining impacts on the physical components of agriculture (e.g., soils, crop productivity, land degradation) with the socioeconomic components (e.g., farm profitability, CAP reform).Water: CRASH: simulates river flows, given data on soils, land use, weather, abstractions, and discharges. Biodiversity: the SPECIES model - which correlates the current distribution of plants and animals with bioclimatic indicators, and then projects their distribution under different future climates, will be used.Flood Model: Regional estimates of sea level rise are extracted from the scenarios of the UK Climate Impacts Programme. Changes in flood frequency will be explored using flood exceedence curves and models that combine sea level change, tidal surge, wave height and erosion. The RegIS Phase 2 study will further develop the regional RegIS socioeconomic scenarios within the context of the UKCIP Socioeconomic scenarios for climate change impact assessment and the Defra Agricultural futures and their implications for the environment. The socioeconomic scenarios will be linked to the UKCIP02 climate scenarios, and together these will form the drivers for the modeling exercises. Interactions between the sectors and systems will be explored by linking the metamodels to one another, e.g., using the data from one to drive another model, and then feeding the output back to the model providing the data. The team is working with stakeholders to ensure that the RegIS project addresses the questions and policy measures that matter to regional decision-makers, and which can be implemented realistically (within the constraints of the research and existing policy framework).The outputs of the project are:- A software tool to allow stakeholders to analyze climate change impacts, their interactions, and adaptive responses.- Final reports and supporting technical reports, which will be reviewed in conjunction with key regional stakeholders. IPCC sea level, land cover, land use, socioeconomic, IPCC DDC socioeconomic data gateway (also part of CEISIN) SRES scenario data downscaled to country level.

CIESIN Centre for International Earth Science Information Network http://www.ciesin.org/Includes data on population, forecasts, SRES scenario data (country level projections).

It is essential to secure tide-gauge data sets of appropriate length and continuity through time to estimate this underlying trend. However, although it can be argued that a 50 year record is the minimum length that should be considered, it is often the case that this length of data will not be available, so it is best to consider all the available data together with the record length. GTOPO30 is a global digital elevation model (DEM) with a horizontal grid spacing of 30 arc seconds (approximately 1 km). GTOPO30 was derived from several raster and vector sources of topographic information. For easier distribution, GTOPO30 has been divided into tiles that can be selected from the map shown above. Detailed information on the characteristics of GTOPO30 including the data distribution format, the data sources, production methods, accuracy, and hints for users, is found in the GTOPO30 README file. Please be sure to check the GTOPO30 Frequently Asked Questions for further information, or if you are having difficulties viewing the data. GTOPO30, completed in late 1996.

This perspective view shows the Strait of Gibraltar, which is the entrance to the Mediterranean Sea from the Atlantic Ocean. Europe (Spain) is on the left. Africa (Morocco) is on the right. The Rock of Gibraltar, administered by Great Britain, is the peninsula in the back left. 30 m resolution from STRM data.Landsat satellite image draped over an elevation model produced by the Shuttle Radar Topography Mission (SRTM). The view is eastward with a 3-times vertical exaggeration to enhance topographic expression. Natural colors of the scene (green vegetation, blue water, brown soil, white beaches) are enhanced by image processing, inclusion of some infrared reflectance (as green) to highlight the vegetation pattern, and inclusion of shading of the elevation model to further highlight the topographic features. DIVA: Case Management page, here the default three cases are listed. Any cases created by the user will be added to the list. The case to be run is ticked. The case chosen will determine the sea level rise scenario, the SRES scenario for socio economic and land-use data, and the adaptation options chosen. We are doing to run the default case, A1Fl_High_Regionalised, with high regionalized sea level scenario and cost benefit analysis (CBA) adaptation optionsFirst of the input parameters screens. Adaptation strategies can be changed here. The screen shows the default adaptation strategies for the A1Fl_High_Regionalised scenario. In summary, the strategies chosen here include the method for setting the level of protection, here cost-benefit analysis; the method for setting the level of beach nourishment, tidal basin nourishment and wetland nourishment (CBA); the type of the CBA used (here, normal); the mode for the failure of dike - in breach mode (chosen here) defenses will instantly fail, under the other option (overtop-breach) the defenses will fail progressively as they are overtopped, until they ultimately breach; the migration mode, here migration will be due to erosion only, rather than erosion and submergence; and whether river floods are included.

This window is followed by the country, administrative unit, tidal basin, river, and coastline segment data. To select one or a number of countries to examine, use the Select subset icon (bottom right). Then use the Apply subset to all tables icon to show results for only this subset (at country scale or lower).The tidal basin window for Honduras shows there is only one tidal basin that has been included in DIVA (highlighted in red). The variables included in the model can be seen in the top right window.This shows the coastline segment data window. The map window shows a number of segments along the north coast of Honduras and the Islas de la Bahia off the coast (Roatn, etc.). The data window shows a number of the variables for each of the coastal segments. The input values windows review the input parameters. The map window shows the vulnerability score for the coastal segments of the Honduras coast, indicating that the variability varies along the north coast from west to east, but the island off the north coast is the most vulnerable.Once the input parameters are set the DIVA model can be run and can then be viewed in the Analysis window.The first of the Results screens shows the global results for the case chosen. The global parameters are listed in the top right window, shown with the values for 2000; each parameter can also be represented in the graph window with results for the timescale of DIVA 2000-2100. This example shows the decrease in the total wetland area decreasing over the timescale of DIVA. The other areas for which results are available are shown in the left hand window: global, GVA region, SRES region, country, administrative unit, tidal basin, and river data.GVA regions are the Global Vulnerability Assessment regions. The division into GVA regions originates from the predecessor project to DINAS-COAST. More information can be found in the help file.This screen shows the results for each of the SRES regions. Again, the timestep chosen is 2100, for the A1Fl High Regionalised scenario. The result displayed is the total adaptation costs for the Central America SRES region. This screen shows the administrative unit results. The timescale has been changed to show the results both in the table and map window for 2100. The results shown are the area of the coastal floodplain in 2100. other parameters that can be displayed include amount of land loss through submergence, the net loss of wetland area, and the numbers of people actually flooded. These results can also be shown as a graph.