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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 Remarks1. Presently Middlesex University, UK ([email protected]) 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
6
8 S
ea L
evel (m
)
1850 1900 1950 2000 2050 2100 Time (yrs)
Observations Scenarios
IPCC TAR range due to SRES emission scenarios
4
Sea Level Under StabilisationIllustrating the large ‘commitment’
IS92a ‘unmitigated’S550
S750HadCM2 Model Results
5
Population and Population Density vs. Distance and Elevation
in 1990
Coastal Population Distribution
6
Coastal Megacities (>8 million people)
UN Forecast for 2010
Istanbul
LagosLima
Buenos Aires Rio de JaneiroMadras
KarachiJakarta
Calcutta
Bombay
Bangkok
Manila
Shanghai
Osaka
Tokyo
Seoul
Tianjin
Dhaka
New York
Los Angeles
7
GLOBAL
REGIONAL
NATIONAL/LOCAL
Scale
UNFCCC(mitigation &
adaptation(?))
Regional Co-operation
Relevant Policies
CoastalManagement(Adaptation)
Bottom/UpTop/Down
Synthesis/
Upscaling
Impact/Adaptation
Assessments
Assessments
Integrated Models
Linking Climate Change to Policy
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.
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Methodology
Relative Sea-LevelRise Scenarios
Raised Flood Levels
Global Sea-levelRise Scenarios
Size of Flood Hazard Zones
People in theHazard Zone
Subsidence
Storm SurgeFlood Curves
Coastal Topography
PopulationDensity
Protection Status(1in 10, 1 in 100, etc.) (“EXPOSURE”)
(“RISK”)Average AnnualPeople Flooded, etc.
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OUTPUTPeople 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.
PHZPAR
PTR
15
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
1.E+03
1.E+04
1.E+05
1.E+06
1.E+07
1.E+08
1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08
National Assessments
Glo
bal
Mo
del
No SLR SLR = 1 m
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ResultsIS92a World
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Global Incidence of Flooding Evolving Protection and No Sea-Level Rise
0
10
20
30 P
eop
le F
lood
ed (
Mill
ion
s/yr
)
1990 2020s 2050s 2080sTime (years)
19
Scenario Valuesfor an IS92a World
Global sea-level rise (cm)
Year
Low Mid High
Subsidence(cm)
GlobalPopulation(billions)
Global GDP(10 12
1990 US$)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 1642100 23 55 96 0 or 17 11.0 189
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People Flooded -- relative to an evolving non-climate baseline
0
1000
2000
3000
2020s 2050s 2080s
% In
cre
as
e
Low Scenario Mid Scenario
High Scenario
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People Flooded -- relative to an evolving non-climate baseline
1
10
100
1000
10000
2020s 2050s 2080s
%In
crea
se
Low Scenario
Mid Scenario
High Scenario
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Vulnerable RegionsMid estimate in the 2080s
C
A
C
B
PEO PLE AT RISK(m illio ns p e r re g io n)
> 50 m illio n
10 - 50 m illio n
< 10 m illio n
re g io n b o und a ry
vulne ra b le isla nd re g io n
Pa c ificO c e a nSM ALLISLAN D S
C a rib b e a n
Ind ia nO c e a nSM ALL ISLAN D S
C
B
A
23
StabilisationIS92a World
24
Sea-Level Scenariosfor one climate sensitivity
IS92a ‘unmitigated’S550
S750HadCM2 Model Results
25
Flood Impacts Under Stabilisation
0
50
100
2020s 2050s 2080s
Pe
op
le F
loo
de
d (
mill
ion
s/y
ear
)
UnmitigatedS750S550
No Climate Change
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Stabilisation and Climate Sensitivity Unmitigated (IS92a) and Stabilisation Scenarios (S750 and S550)
Calculations by Jason Lowe, Hadley Centre
0
50
100
150
1950 2000 2050 2100 2150 2200
Time
Sea
lev
el
(cm
)
High ClimateSensitivity
Mid ClimateSensitivity
Low ClimateSensitivity
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Stabilisation in an ‘IS92a World’ Additional People Flooded (millions/year)
0
20
40
2020s 2050s 2080s 2110s 2140s
Ad
dit
ion
al P
eop
le F
loo
ded
S550 S750 IS92a
(b) Low climate sensitivity
0
100
200
2020s 2050s 2080s 2110s 2140s
Ad
dit
ion
al P
eop
le F
loo
ded
S550 S750 IS92a
(c) Mid climate sensitivity (HadCM2)
0
200
400
600
2020s 2050s 2080s 2110s 2140s
Ad
dit
ion
al P
eop
le F
loo
ded
S550 S750 IS92a
(d) High climate sensitivity
0
20
40
1990 2020s 2050s 2080s 2110s 2140s
Peo
ple
Flo
od
ed
(a) Baseline: No global sea-level rise
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ResultsSRES Scenarios
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SRES: Sea-Level Rise ScenariosHadCM3 Model -- Climate Sensitivity Constant
0.0
0.1
0.2
0.3
0.4
1990 2010 2030 2050 2070 2090
Time (yrs.)
Glo
ba
l-M
ea
n R
ise
(m
)
A1FIB1
A2B2
30
Global Incidence of Flooding Evolving Protection and No Sea-Level Rise
0
10
20
30
1990 2020s 2050s 2080s
AA
PF
(m
illi
on
s/ye
ar)
A1FI
A2
B1
B2
31
Additional People Floodedwith global sea-level rise
0
10
20
2020s 2050s 2080s
AA
PF
(m
illi
on
s/y
ear)
A1FI
A2
B1
B2
32
Stabilisation under SRESfollowing Swart et al (2002)
0
10
20
30
40
A1FI A2 B1 B2
Peo
ple
Flo
od
ed (
mil
lio
ns/
yr.)
No SLR Unmitigated
"S650" "S550"
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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 21 st 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/