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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
PLAN
• The Coast at the turn of the 21st century
• Impacts and Responses to Sea-Level Rise
• Assessment Needs
• Examples
• Concluding Remarks
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
Tianjin
Dhaka
Seoul
Osaka
Istanbul
Tokyo
New York
Shanghai
Los Angeles
Manila
Bangkok
Lagos
Bombay
Lima
Karachi
Buenos Aires
Rio de Janeiro
Madras
Jakarta
Calcutta
Taken from Nicholls (1995)
NIGHT LIGHTS AND POP. DENSITY
Night lights
Population density (GPW2)
Subsidence in
Bangkok
Subsidence
bowl
Subsiding Coastal Megacities
(during the 20th Century)
Tianjin (2 m)
Dhaka
Seoul
Osaka (3 m)
Istanbul
Tokyo (5 m)
New York
Shanghai (3 m)
Los Angeles
Manila
Lagos
Lima
Karachi
Buenos Aires
Bangkok (2 m)
Bombay
Rio de Janeiro
Madras
Jakarta
Calcutta
Coastal Ecosystems
KEY:
● mangroves, o saltmarsh, x coral reefs
Impacts and Responses to Sea-Level
Rise
Co-Evolving Coastal System
SENSITIVITY
ADAPTIVE
CAPACITY
EXPOSURE
NATURAL SYSTEM
MULTIPLE
STRESSES1
BOUNDARY
CONDITIONS
SENSITIVITY
EXPOSURE
ADAPTIVE
CAPACITY
SOCIO-ECONOMIC
SYSTEM
1. External stresses are scale-dependent and include climate change and global-mean sea-level rise.
Relative Sea-Level Rise
Major Effects And Selected Responses
NATURAL SYSTEM
EFFECTS
1. Inundation,
flood and
storm damage
a. Surge (sea)
b. Backwater effect
(river)
2. Wetland loss (and change)
SELECTED ADAPTATIONS
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3. Erosion (direct and indirect
morphological change)
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4. Saltwater
Intrusion
a. Surface Waters
b. Groundwater
5. Rising water tables/ impeded
drainage
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Dikes/surge barriers,
Building codes/floodwise buildings,
Land use planning/hazard delineation.
Land use planning,
Managed realignment/ forbid hard defences,
Nourishment/ sediment management.
Coast defences,
Nourishment,
Building setbacks.
Saltwater intrusion barriers,
Change water abstraction,
Freshwater injection.
Upgrade drainage systems,
Polders,
Change land use,
Land use planning/hazard delineation.
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
Mitigation
Climate
Climate
variability
change
Impacts
Information,
Planning,
Implemen -
Monitoring,
Awareness
Design
tation
Evaluation
Existing
management
practices
Other
Policy
stresses
criteria
Coastal
development
objectives
Adaptation
Relative Sea-Level Rise
Major Effects And Selected Responses
NATURAL SYSTEM
EFFECTS
1. Inundation,
flood and
storm damage
a. Surge (sea)
b. Backwater effect
(river)
2. Wetland loss (and change)
SELECTED ADAPTATIONS






3. Erosion (direct and indirect
morphological change)



4. Saltwater
Intrusion
a. Surface Waters
b. Groundwater
5. Rising water tables/ impeded
drainage







Dikes/surge barriers,
Building codes/floodwise buildings,
Land use planning/hazard delineation.
Land use planning,
Managed realignment/ forbid hard defences,
Nourishment/ sediment management.
Coast defences,
Nourishment,
Building setbacks.
Saltwater intrusion barriers,
Change water abstraction,
Freshwater injection.
Upgrade drainage systems,
Polders,
Change land use,
Land use planning/hazard delineation.
The Thames Barrier
Accommodation on the Isle of Wight
raising new homes to EA elevation commendations
Assessment Needs
Methods
Top/Down
Scale
Relevant
Policies
Bottom/Up
GLOBAL
Integrated
Models and
Assessments
Impact and
Adaptation
Assessments
Greenhouse Gas
Emissions
REGIONAL
Regional
Co-operation
NATIONAL/
LOCAL
Coastal
Management
Examples
Exposure Analysis (global)
• Impact Analysis (global)
• Impact Analysis (national)
•
Exposed Population vs. Sea-Level Rise
(by country in 1995 and assuming no adaptation)
Number of Countries
150
10%
25%
50%
100%
100
50
0
0
5
10
15
Sea-Level Rise (m)
20
25
Exposed Population vs. Sea-Level Rise
(by country in 1995 and assuming no adaptation)
% Countries Affected
100
10%
25%
50%
100%
75
50
25
0
0
5
10
15
Sea-Level Rise (m)
20
25
Global Flood Impact Methodology
Global Sea-level
Rise Scenarios
Subsidence
Storm Surge
Flood Curves
Relative Sea-Level
Rise Scenarios
Coastal
Topography
Raised Flood Levels
Population
Density
Size of Flood
Hazard Zones
Protection Status
(1in 10, 1 in100, etc.)
People in the
Hazard Zone
(“EXPOSURE”)
Average Annual
People Flooded,
People to Respond
(“RISK”)
Global Flood Impact Methodology
Global Sea-level
Rise Scenarios
Subsidence
Storm Surge
Flood Curves
Relative Sea-Level
Rise Scenarios
Coastal
Topography
Raised Flood Levels
Population
Density
Size of Flood
Hazard Zones
Protection Status
(1in 10, 1 in100, etc.)
People in the
Hazard Zone
(“EXPOSURE”)
Average Annual
People Flooded,
People to Respond
(“RISK”)
Sea-Level Rise across Climate Sensitivity
Unmitigated (IS92a) and Stabilisation Scenarios (S750 and S550)
(Nicholls and Lowe, 2004)
150
IS92a
S750
S550
Sea level (cm)
High
Climate
Sensitivity
100
Mid
Climate
Sensitivity
50
Low
Climate
Sensitivity
0
1950
2000
2050
2100
Time
2150
IS92a
S750
S550
IS92a
S750
S550
2200
Flooding (Nicholls and Lowe, 2004)
Additional People Flooded (millions/year) in an ‘IS92a World’
Additional People Flooded
40
People Flooded
(a) Baseline: No global sea-level rise
20
0
2020s
2050s
2080s
2110s
2140s
Additional People Flooded
40
(b) Low climate sensitivity
S550
S750
IS92a
20
0
2020s
2050s
2080s
2110s
2140s
(c) Mid climate sensitivity (HadCM2)
S550
S750
IS92a
100
0
2020s
Additional People Flooded
1990
200
2050s
2080s
2110s
2140s
600
(d) High climate sensitivity
S550
S750
IS92a
400
200
0
2020s
2050s
2080s
2110s
2140s
Flooded Population
Sea-Level Rise and Protection Response
SRES scenarios 2080s ‘Fast Track’ (Nicholls and Lowe, 2006)
1000
People (millions/year)
Constant Protection (in 1990) A1/B1
Constant Protection (in 1990) A2
100
Constant Protection (in 1990) B2
Evolving Protection (with GDP/capita) A1FI
CP
Evolving Protection (with GDP/capita) A2
10
Evolving Protection (with GDP/capita) B2
Enhanced Protection A1FI
EvP
Enhanced Protection A2
EnP
1
Enhanced Protection B2
0
10
20
Sea-level rise (cm)
30
40
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
0
0.1
0.2
0.3
0.4
0.5
0.6
m
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
metres
Foresight
e Flood Risks
o s: Comparative Ris k
pected Ann ual
bility o f Floo din g
Flooding and coastal areas
(From Foresight Study)
Presen t Day 200 2
Pro bab ility of Inu ndatio n to a d epth
greater th an 0 .0m
Ne gligible
Low
M edium
High
World M arkets 2050's
World M arkets 20 80's
Negligible Increase
Low Increase
Medium Increase
High Increase
Negligible Increase
Low Increase
Medium Increase
High Increase
Decrease
Decrease
Outside IFP
Outside IFP
Ve ry H igh
Outsi de IFP
ariso ns represen t the
etween Pres ent Day 2 00 2
o res ig ht Fu ture Scen arios
Na tiona l E nte rpr ise 2 080's
Local St ewards hip 2080's
Glob al R e spon sib ility 20 80's
Negligible Increase
Low Increase
Medium Increase
High Increase
Negligible Increase
Low Increase
Medium Increase
High Increase
Negligible Increase
Low Increase
Medium Increase
High Increase
Decrease
Decrease
Decrease
Outside IFP
Outside IFP
Outside IFP
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
o
long-term sea-level rise (decades/centuries)
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