Some Global Impacts of SeaLevel Rise:

1
Some Global Impacts of Sea-Level Rise A Case
Study of Flooding Robert J. Nicholls1

• Plan
• Sea Level and the Coast
• Global Assessment
• Methods
• IS92a Results -- across the range of climate
  sensitivity
• SRES Results -- across different socio-economic
  futures
• Concluding Remarks
• 1. Presently Middlesex University, UK
  (r.nicholls_at_mdx.ac.uk)
• From 1 January 2004, University of
  Southampton, UK

2
Processes controlling sea-levelchange

• Relative sea-level changes

3
Sea-Level Rise at New York City1850 to 2100
IPCC TAR range due to SRES emission scenarios
4
Sea Level Under StabilisationIllustrating the
large commitment
HadCM2 Model Results
5
Coastal Population Distribution
Population and Population Density vs. Distance
and Elevationin 1990
6
Coastal Megacities (gt8 million people)UN
Forecast for 2010
Tianjin
Dhaka
Seoul
Osaka
Istanbul
Tokyo
New York
Shanghai
Los Angeles
Manila
Bangkok
Lagos
Bombay
Lima
Karachi
Madras
Jakarta
Rio de Janeiro
Buenos Aires
Calcutta
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Linking Climate Change to Policy
Scale
Relevant Policies
Assessments
Top/Down
Bottom/Up
Integrated Models
GLOBAL
Synthesis/ Upscaling
REGIONAL
Impact/
NATIONAL
Adaptation
/LOCAL
Assessments
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Coastal Flood Plain
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Sea-level rise and flood return period
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Research Questions

• With consistent climate and socio-economic
  scenarios (e.g., IS92a)
• 1. Is global-mean sea-level rise a problem, if
  ignored?
• 2. What are the benefits of stabilising
  greenhouse forcing (mitigation policy)?

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Background

• Developed from the original Global Vulnerability
  Analysis (Hoozemans et al., 1993)
• Based on a database of 192 polygons (roughly
  speaking the coastal countries)
• Storm characteristics are assumed constant
• Assumes a constant slope across the flood plain
• Defence standards derived from GDP/capita
• Failure compromises entire flood plain
• Results are only meaningful at the regional and
  global scale.

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Improvements

• Dynamic sea level, coastal population and
  standard of protection scenarios
• But standard of protection only evolves in
  response to the 1990 climate (i.e. sea-level rise
  is ignored)
• Higher costs of protecting deltaic areas are
  considered
• Increased flood risk within the coastal flood
  plain is evaluated
• Minimum 1990 defence standards are assumed as 1
  in 10 year.

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Methodology
Global Sea-level Rise Scenarios
Subsidence
Relative Sea-Level
Storm Surge
Rise Scenarios
Flood Curves
Coastal
Raised Flood Levels
Topography
Size of Flood Hazard Zones
Population
Density
Protection Status (1in 10, 1 in 100, etc.)
People in the Hazard Zone
(EXPOSURE)
Average Annual People Flooded, etc.
(RISK)
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OUTPUT
People in the hazard zone (PHZ) number of people
exposed to flooding by storm surge Average
annual people flooded (AAPF) the average annual
number of people who experience flooding by storm
surge (also described as people at risk (PAR))
People to respond (PTR) the average annual
number of people who experience flooding by storm
surge more than once per year.
PAR
PHZ
PTR
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• Population Scenario
• population growth in the coastal flood plain is
  double national trends.
• Protection Scenario
• in phase evolving protection with increasing
  GDP/capita
• (and ignoring sea-level rise)

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ValidationModel vs. National estimates
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ResultsIS92a World
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Global Incidence of Flooding Evolving Protection
and No Sea-Level Rise
30
20
People Flooded (Millions/yr)
10
0
1990
2020s
2050s
2080s
Time (years)
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Scenario Valuesfor an IS92a World
Global sea-
Year
Subsidence
Global
Global GDP
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level rise (cm)
(cm)
(10
Population (billions)
1990 US)
Low
Mid
High
1990
0
0
0
0
5.3
20
2020s
4
11
22
0 or 5
8.1
65
2050s
10
27
49
0 or 10
9.8
113
2080s
19
45
80
0 or 14
10.7
164
2100
23
55
96
0 or 17
11.0
189
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People Flooded -- relative to an evolving
non-climate baseline
3000
Low Scenario
Mid Scenario
High Scenario
2000
Increase
1000
0
2020s
2050s
2080s
21
People Flooded -- relative to an evolving
non-climate baseline
10000
Low Scenario
Mid Scenario
High Scenario
1000
Increase
100
10
1
2020s
2050s
2080s
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Vulnerable RegionsMid estimate in the 2080s
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StabilisationIS92a World
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Sea-Level Scenariosfor one climate sensitivity
HadCM2 Model Results
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Flood Impacts Under Stabilisation
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Stabilisation and Climate Sensitivity
Unmitigated (IS92a) and Stabilisation Scenarios
(S750 and S550) Calculations by Jason Lowe,
Hadley Centre
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Stabilisation in an IS92a World Additional
People Flooded (millions/year)
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ResultsSRES Scenarios
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SRES Sea-Level Rise ScenariosHadCM3 Model --
Climate Sensitivity Constant
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Global Incidence of Flooding Evolving Protection
and No Sea-Level Rise
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Additional People Floodedwith global sea-level
rise
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Stabilisation under SRESfollowing Swart et al
(2002)
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Concluding Remarks

• Sea-level rise could be a serious problem for
  coastal flooding, but the uncertainties are
  large
• Mitigation reduces but does not avoid flood
  impacts, and some impacts are only delayed
• A combined strategy of mitigation and adaptation
  would seem prudent -- but what mixture?
• Next steps the DINAS-COAST Project

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RELEVANT PUBLICATIONS

• HOOZEMANS, F.M.J., MARCHAND, M., PENNEKAMP, H.A.,
  STIVE, M., MISDORP, R. BIJLSMA, L., 1992. The
  impacts of sea-level rise on coastal areas Some
  global results. In Proceedings The Rising
  Challenge of the Sea, Margarita Island,
  Venezuela, March 9-13 1992. NOAA, Silver Spring,
  Md. pp. 275-292.
• HOOZEMANS, F.M.J., MARCHAND, M. PENNEKAMP,
  H.A., 1993. A Global Vulnerability Analysis
  Vulnerability Assessment for Population, Coastal
  Wetlands and Rice Production on a Global Scale.
  2nd edition. Delft Hydraulics, the Netherlands.
• PARRY, M., ARNELL, N., HULME, M., NICHOLLS, R.
  LIVERMORE, M. 1998. Adapting to the inevitable.
  Nature, 395, 741.
• NICHOLLS, R.J., HOOZEMANS, F.M.J., MARCHAND, M.
  1999. Increasing flood risk and wetland losses
  due to global sea-level rise Regional and global
  analyses. Global Environmental Change, 9,
  S69-S87.
• PARRY, M., ARNELL, N., McMICHAEL, T., NICHOLLS,
  R., MARTENS, P., KOVATS, S., LIVERMORE, M.,
  ROSENZWEIG, C., IGLESIAS, A. FISCHER, G., 2001.
  Millions at risk defining critical climate
  threats and targets. Global Environmental Change,
  11(3), 1-3.
• ARNELL, N.W., CANNELL, M.G.R., HULME, M., KOVATS,
  R.S., MITCHELL, J.F.B., NICHOLLS, R.J. PARRY,
  M.L., LIVERMORE,, M.T.J. WHITE, A. 2002. The
  consequences of CO2 stabilisation for the impacts
  of climate change Climatic Change, 53, 413-446.
• NICHOLLS, R.J. and SMALL, C., 2002. Improved
  Estimates of Coastal Population and Exposure to
  Hazards Released. EOS Transactions, 83(2), 301
  and 305. (downloadable at www.survas.mdx.ac.uk)
• NICHOLLS, R.J. 2002. Analysis of global impacts
  of sea-level rise A case study of flooding.
  Physics and Chemistry of the Earth, 27,
  1455-1466.
• SMALL, C. NICHOLLS, R.J. 2003, A Global
  Analysis of Human Settlement in Coastal Zones,
  Journal of Coastal Research, 19(3), 584-589.
• NICHOLLS, R.J., 2003. Coastal Flooding and
  Wetland Loss in the 21st Century Changes Under
  The SRES Climate And Socio-Economic Scenarios.
  Global Environmental Change, accepted.
• NICHOLLS, R.J. LOWE, J.A., in review. Benefits
  of Climate Mitigation for Coastal Areas.
  Submitted to Global Environmental Change.

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Web Sites

• SURVAS
• http//www.survas.mdx.ac.uk/
• DINAS-COAST
• http//www.pik-potsdam.de/dinas-coast/