Assessing Potential Impacts and Responses to Sea-level Rise Robert J. Nicholls School of Civil Engineering and the Environment and Tyndall Centre for Climate Change Research University of Southampton, UK Workshop on “Understanding Sea Level Rise and Variability ” 6 to 9 June 2006 UNESCO, Paris

The Coast at the turn of the 21 st century Impacts and Responses to Sea-Level Rise Assessment Needs Examples Concluding Remarks PLAN

The Coast at the turn of the 21st century

Elevation and population density maps for Southeast Asia

Coastal Population vs. Distance and Elevation Global estimates for 1990 (Small and Nicholls, 2003)

Coastal Megacities (>8 million people) UN Forecast for 2010 Istanbul Lagos Lima Buenos Aires Rio de Janeiro Madras Karachi Jakarta Calcutta Bombay Bangkok Manila Shanghai Osaka Tokyo Seoul Tianjin Dhaka New York Los Angeles Taken from Nicholls (1995)

NIGHT LIGHTS AND POP. DENSITY Population density (GPW2) Night lights

Subsidence in Bangkok Subsidence bowl

Subsiding Coastal Megacities (during the 20 th Century) Istanbul Lagos Lima Buenos Aires Rio de Janeiro Madras Karachi Jakarta Calcutta Bombay Bangkok (2 m) Manila Shanghai (3 m) Osaka (3 m) Tokyo (5 m) Seoul Tianjin (2 m) Dhaka New York Los Angeles

Coastal Ecosystems KEY: ● mangroves, o saltmarsh, x coral reefs

Impacts and Responses to Sea-Level Rise

MULTIPLE STRESSES 1 BOUNDARY CONDITIONS NATURAL SYSTEM SENSITIVITY ADAPTIVE CAPACITY SOCIO-ECONOMIC SYSTEM SENSITIVITY ADAPTIVE CAPACITY EXPOSURE Co-Evolving Coastal System 1. External stresses are scale-dependent and include climate change and global-mean sea-level rise.

NATURAL SYSTEM EFFECTS SELECTED ADAPTATIONS 1. Inundation, flood and storm damage a. Surge (sea)  Dikes/surge barriers,  Building codes/floodwise buildings,  Land use planning/hazard delineation. b. Backwater effect (river) 2. Wetland loss (and change)  Land use planning,  Managed realignment/ forbid hard defences,  Nourishment/ sediment management. 3. Erosion (direct and indirect morphological change)  Coast defences,  Nourishment,  Building setbacks. 4. Saltwater Intrusion a. Surface Waters  Saltwater intrusion barriers,  Change water abstraction,  Freshwater injection. b. Groundwater 5. Rising water tables/ impeded drainage  Upgrade drainage systems,  Polders,  Change land use,  Land use planning/hazard delineation. Relative Sea-Level Rise Major Effects And Selected Responses

North Sea Storm Surge 31 January/1 February 1953

The Thames Barrier

RESPONDING TO COASTAL HAZARDS Planned Retreat Accommodation Protect - soft - hard

ADAPTATION A Continuous Process Climate variability Coastal development objectives Climate change Policy criteria Other stresses Information, Awareness Planning, Design Implemen- tation Impacts Mitigation Adaptation Existing management practices Monitoring, Evaluation

NATURAL SYSTEM EFFECTS SELECTED ADAPTATIONS 1. Inundation, flood and storm damage a. Surge (sea)  Dikes/surge barriers,  Building codes/floodwise buildings,  Land use planning/hazard delineation. b. Backwater effect (river) 2. Wetland loss (and change)  Land use planning,  Managed realignment/ forbid hard defences,  Nourishment/ sediment management. 3. Erosion (direct and indirect morphological change)  Coast defences,  Nourishment,  Building setbacks. 4. Saltwater Intrusion a. Surface Waters  Saltwater intrusion barriers,  Change water abstraction,  Freshwater injection. b. Groundwater 5. Rising water tables/ impeded drainage  Upgrade drainage systems,  Polders,  Change land use,  Land use planning/hazard delineation. Relative Sea-Level Rise Major Effects And Selected Responses

The Thames Barrier

Accommodation on the Isle of Wight raising new homes to EA elevation commendations

GLOBAL REGIONAL NATIONAL/ NATIONAL/LOCAL Greenhouse Gas Emissions RegionalCo-operation Bottom/Up RelevantPoliciesScale CoastalManagement Top/Down Integrated Models and Assessments Impact and AdaptationAssessments Methods Assessment Needs

Examples Exposure Analysis (global) Impact Analysis (global) Impact Analysis (national)

Exposed Population vs. Sea-Level Rise (by country in 1995 and assuming no adaptation)

Exposed Population vs. Sea-Level Rise (by country in 1995 and assuming no adaptation)

Global Flood Impact Methodology Relative Sea-Level Rise Scenarios Raised Flood Levels Global Sea-level Rise Scenarios Size of Flood Hazard Zones People in the Hazard Zone Subsidence Storm Surge Flood Curves Coastal Topography Population Density Protection Status (1in 10, 1 in100, etc.) Average Annual People Flooded, People to Respond (“EXPOSURE”) (“RISK”)

Global Flood Impact Methodology Relative Sea-Level Rise Scenarios Raised Flood Levels Global Sea-level Rise Scenarios Size of Flood Hazard Zones People in the Hazard Zone Subsidence Storm Surge Flood Curves Coastal Topography Population Density Protection Status (1in 10, 1 in100, etc.) Average Annual People Flooded, People to Respond (“EXPOSURE”) (“RISK”)

Sea-Level Rise across Climate Sensitivity Unmitigated (IS92a) and Stabilisation Scenarios (S750 and S550) ( Nicholls and Lowe, 2004) IS92a S750 S550 IS92a S750 S550 IS92a S750 S550

Flooding (Nicholls and Lowe, 2004) Additional People Flooded (millions/year) in an ‘IS92a World’

Flooded Population Sea-Level Rise and Protection Response SRES scenarios 2080s ‘Fast Track’ (Nicholls and Lowe, 2006) CP EnP EvP

Foresight Flood and Coastal Defence Study -- Coastal Drivers in OST Foresight Study Based on a source-pathway-receptor framework: Relative sea-level rise (source). Surges (source). Waves (source). Coastal morphology and sediment supply (pathway). Plus many other drivers – population, GDP, etc.

Geological Observations Of Uplift/Subsidence (from Shennan and Horton, 2002) Subsidence Uplift

Uncertainty in Regional Sea-Level Change 1990 to 2080s IPCC Third Assessment Report m

metres Change in 50 year event from a storm surge model for 2080s medium-high emissions and 50 cm SLR Hadley Centre for Climate Change Research

Flooding and coastal areas (From Foresight Study)

Concluding Thoughts The coast is dynamic experiencing profound and diverse change; Rising sea levels at all scales are an important component of this change; Rising sea levels are associated with significant risks, requiring long-term strategic responses; Small islands and deltas are most threatened; Adaptation has the potential to manage most expected challenges; There is an ongoing research need to underpin these needs o long-term sea-level rise (decades/centuries) o extreme events (today and tomorrow)

Sample DIVA Outputs Estimated People Flooded (per year) by surges in 2000

Assessing Potential Impacts and Responses to Sea-level Rise Robert J. Nicholls School of Civil Engineering and the Environment and Tyndall Centre for Climate Change Research University of Southampton, UK Workshop on “Understanding Sea Level Rise and Variability ” 6 to 9 June 2006 UNESCO, Paris