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Table 4

Population at Risk in 2085 for Coastal Flooding

Population at Risk in the

Additional Population at

Total Population

Absence of Climate Change

Risk Because of Climate Change

at Risk

Units

Millions

Percentage of

Millions

Percentage of

Millions

Percentage of

Global Population

Baseline 1990

0.2

A1FI 2085

1 to 3

10 to 42

0.1 to 0.5

11 to 45

0.1 to 0.6

A2 2085

30 to 74

0.2 to 0.5

50 to 277

0.4 to 2.0

80 to 351

0.6 to 2.5

B2 2085

5 to 35

0 to 0.3

27 to 66

0.3 to 0.6

32 to 101

0.3 to 1.0

B1 2085

2 to 5

0 to 0.1

3 to 34

0 to 0.5

5 to 39

0 to 0.5

Source: R. J. Nicholls, "Coastal Flooding and Wetland Loss in the 21st Century: Changes under the SRES Climate and Socio-Economic Scenarios," Global

Environmental Change 14, no. 1 (2004).

by a storm surge in 2085 with and without cli-

warmest (and richest) scenario has the least

mate change, assuming that populations

total water stress.

would be attracted preferentially to the coast

This is all the more striking given that the

and that some adaptations would occur with a

calculations informing Table 3 assume zero

30-year lag time.40 The low and high end of the

adaptation despite the ready availability of

time-tested adaptive responses on both the

ranges for populations at risk for each entry in

supply and demand side (e.g., water storage

Table 4 assume low and high subsidence due

facilities to augment water supplies during

to non-climate-change-related human causes,

drier periods, or water pricing and other con-

respectively.

servation measures).39 Thus it overestimates

The main conclusion one draws from

Table 4 is that the warmest and richest sce-

the populations at risk in all scenarios. These

nario (A1FI) produces only slightly larger

overestimates, however, are greatest for the

coastal flooding damages than the coolest

A1FI (richest) scenario and lowest for the A2

scenario (B1). This conclusion is at least par-

(poorest) scenario. Although the ranking

tially due to the fact that although the calcu-

among the scenarios would not change, the

lations in Table 4 make a creditable effort to

differences in the populations at risk

incorporate improvements in adaptive capac-

between the various scenarios would have

ity due to increasing wealth, some of the

been magnified had adaptation been consid-

underlying assumptions are questionable.

ered.

For instance, the scenarios in Table 4 allow

societies to implement measures to reduce the

Coastal Flooding

risk of coastal flooding in response to 1990

The FTA's estimates of the population at

surge conditions, but ignore such changes due

risk for coastal flooding with and without any

to subsequent sea level rise.41 But one would

climate change between 1990 and 2085 are

shown in Table 4. Note that sea level will rise

expect that whenever any measures are imple-

relative to the land not only because of climate

mented, society would consider the latest

change but also because the land may subside

available data and information on the surge

for a variety of reasons not related to climate

situation at the time the measures are initiat-

change (e.g., extraction of water, gas, or oil

ed. That is, if the measure is initiated in, say,

under the coastline). In this table, population

2050, the measure's design would at least con-

at risk is measured by the average number of

sider sea level and sea level trends as of 2050,

people who would experience coastal flooding

rather than merely the 1990 level.