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
From 1 January 2004, University of Southampton, UK

2. Processes controlling sea-level change
Relative sea-level changes

3. Sea-Level Rise at New York City 1850 to 2100
IPCC TAR range
due to SRES emission scenarios

4. Sea Level Under Stabilisation Illustrating the large ‘commitment’
IS92a ‘unmitigated’
S550
S750
HadCM2 Model Results

5. Population and Population Density vs. Distance and Elevation in 1990
Coastal Population Distribution
Population and Population Density vs. Distance and Elevation in 1990

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

7. Linking Climate Change to Policy
Scale
Assessments
Relevant Policies
Top/Down
Bottom/Up
UNFCCC
(mitigation &
adaptation(?))
GLOBAL
Integrated
Models
Synthesis/
Upscaling
Regional
Co-operation
REGIONAL
Impact/
Coastal
Management
(Adaptation)
NATIONAL
Adaptation
/LOCAL
Assessments

8. Coastal Flood Plain

9. Sea-level rise and flood return period

10. 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)?

11. 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.

12. 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.

13. Methodology Global Sea-level Rise Scenarios Subsidence Storm Surge
Relative Sea-Level
Flood Curves
Rise Scenarios
Coastal
Raised Flood Levels
Topography
Population
Size of Flood
Hazard Zones
Density
Protection Status
(1in 10, 1 in 100, etc.)
People in the
Hazard Zone
(“EXPOSURE”)
Average Annual
People Flooded, etc.
(“RISK”)

14. 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

15. Population Scenario Protection 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)

16. Validation Model vs. National estimates

17. Results IS92a World

18. Global Incidence of Flooding Evolving Protection and No Sea-Level Rise30 20
People Flooded (Millions/yr) 10
1990
2020s
2050s
2080s
Time (years)

19. Scenario Values for an IS92a World
Year
Global sea-
Subsidence
Global
Global GDP
level rise (cm)
(cm)
Population
(billions)
(10 12
1990 US$)
Low
Mid
High
1990
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

20. People Flooded -- relative to an evolving non-climate baseline
3000
Low Scenario
Mid Scenario
High Scenario
2000
% Increase
1000
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

22. Vulnerable Regions Mid estimate in the 2080s

23. Stabilisation IS92a World

24. Sea-Level Scenarios for one climate sensitivity
IS92a ‘unmitigated’
S550
S750
HadCM2 Model Results

25. Flood Impacts Under Stabilisation50
100
2020s
2050s
2080s
People Flooded (millions/year)
Unmitigated
S750
S550
No Climate Change

26. Stabilisation and Climate Sensitivity Unmitigated (IS92a) and Stabilisation Scenarios (S750 and S550) Calculations by Jason Lowe, Hadley Centre

27. Stabilisation in an ‘IS92a World’ Additional People Flooded (millions/year)

28. Results SRES Scenarios

29. SRES: Sea-Level Rise Scenarios HadCM3 Model -- Climate Sensitivity Constant

30. Global Incidence of Flooding Evolving Protection and No Sea-Level Rise

31. Additional People Flooded with global sea-level rise

32. Stabilisation under SRES following Swart et al (2002)

33. 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

34. RELEVANT PUBLICATIONS
HOOZEMANS, F.M.J., MARCHAND, M., PENNEKAMP, H.A., STIVE, M., MISDORP, R. & BIJLSMA, L., The impacts of sea-level rise on coastal areas: Some global results. In: Proceedings ‘The Rising Challenge of the Sea’, Margarita Island, Venezuela, March NOAA, Silver Spring, Md. pp
HOOZEMANS, F.M.J., MARCHAND, M. & PENNEKAMP, H.A., 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 Adapting to the inevitable. Nature, 395, 741.
NICHOLLS, R.J., HOOZEMANS, F.M.J., & MARCHAND, M 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., 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 The consequences of CO2 stabilisation for the impacts of climate change Climatic Change, 53,
NICHOLLS, R.J. and SMALL, C., Improved Estimates of Coastal Population and Exposure to Hazards Released. EOS Transactions, 83(2), 301 and 305. (downloadable at
NICHOLLS, R.J Analysis of global impacts of sea-level rise: A case study of flooding. Physics and Chemistry of the Earth, 27,
SMALL, C. & NICHOLLS, R.J. 2003, A Global Analysis of Human Settlement in Coastal Zones, Journal of Coastal Research, 19(3),
NICHOLLS, R.J., 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.

35. Web Sites SURVAS DINAS-COAST http://www.survas.mdx.ac.uk/