AdaptCost
Briefing Paper 3: Coastal Adaptation – Africa Review and New Estimates
Key Messages
1.
The coastal zones of Africa contain high populations, significant economic activity and important ecosystems.
These are at risk from future sea level rise and storm surge. With a large and growing population in coastal
zones and a low adaptive capacity, many African countries are highly vulnerable.
2.
In the absence of adaptation, the physical, human and financial impacts of climate change on coastal zones
will be significant. Coastal adaptation is therefore likely to be a priority area. To investigate this, the
AdaptCost study has commissioned new analysis using the DIVA model to provide aggregate Africa level
analysis and dis-aggregated outputs by country for impacts and adaptation costs.
3.
These runs indicate that without adaptation, the impacts and economic costs to coastal zones could be a
significant risk for Africa, with over two million people anticipated to be flooded each year by the 2030, rising
to 5 million per year by 2050 (A1B mid-range scenario). In the longer-term these risks increase significantly
with an estimated 16 million people flooded each year in 2100 with (A1B, 43-cm rise).
4.
The model has also estimated the economic costs associated with the impacts of flooding and the loss of
ecosystems. Without adaptation, the total costs for the A1B scenario are estimated at US$ 1.6 billion/year in
2030 (1995 prices), rising rapidly to $7.5 billion/year by 2050 (1995 prices). In the longer term, impacts rise
significantly, up to $38 billion/year in 2100 (1995 prices). Note that a large proportion (around 50%) of these
future costs is due to socio-economic change and population growth. The economic costs increase with
higher sea level rise scenarios, and using higher scenarios from the literature, the model reports a plausible
upper estimate of $50 billion / year by 2100.
5.
The model also looks at adaptation costs and benefits for two protection measures. The costs of adaptation
are estimated at approximately $2 billion/year for Africa in the period 2030 – 2100 (A1B) and the benefits are
significant: with adaptation, residual damage costs are reduced to around $1 billion / year (1995 prices). The
analysis shows that adaptation can reduce the risk of flooding and the economic costs of sea level rise very
significantly, at relatively low cost. However, the costs of adaptation rise significantly with higher sea level rise
scenarios. Using plausible scenarios from the recent literature, the costs of adaptation could increase to $5 to
8 billion/year by 2100 for Africa. It is stressed that these values do not address all categories of impacts and
they do not include the additional deficit to better cope with current coastal flood risks in Africa. They could
therefore be considered an underestimate. However, they are primarily based on technical measures.
6.
The national DIVA results show impacts and adaptation costs in several countries are particularly important.
For the numbers of people flooded, high risks are anticipated for Mozambique, Cameroon, Tanzania,
Morocco and Egypt. For economic damages, high damages are projected in Egypt (in particular) and also
Algeria, Morocco, South Africa, Tunisia, Libya and Cameroon. In absolute terms, the highest adaptation costs
occur in Mozambique, Guinea, Guinea-Bissau, Nigeria, Somalia and South Africa. Note that high impact costs
and adaptation costs are not automatically correlated.
7.
The study has also reviewed other estimates. The recent World Bank study also applies the DIVA model, but
adds additional some adaptation costs, and considers a higher sea level rise scenario (A2, higher SLR). It
estimates costs for Africa at $4 to 6 billion/year for Africa in the period 2010 – 2050.
8.
There are also a number of national studies, including analysis in Benin, Egypt, Kenya, Nigeria, Senegal,
Tanzania and South Africa, as well as emerging studies in a much larger group of countries which will be
available by the end of this year. Comparing the aggregate estimates for Africa with these individual country
studies is difficult. Results for some parameters are of the same order of magnitude, while others show
significant differences. These differences arise from the difference in defining coasts and wetland area and
the level of spatial detail the analysis, but also from the framework adopted, i.e. whether existing and future
protection costs are included, and whether action is to pre-defined levels or within an optimal analysis.
9.
Finally, further work is required to better understand the implications of sea-level rise for Africa in broad
sense, but also to move to national and sub-national assessments. These can also address adaptation in a
local context and the linkages with development, as well as considering more realistic adaptation measures.
1
Introduction
All of these coastal zones support significant
economic activity, associated with agriculture and
tourism, as well as containing commercial and
industrial facilities. These zones contribute
significantly to wealth and economic activity, as
well as providing much wider economic benefits
through ecosystem services.
The AdaptCost study has reviewed the evidence
on the costs of adaptation in Africa. This includes
consideration of different aggregation scales and
evidence, such as:

Aggregated continental level studies and
regional studies.

Major country initiatives and national studies

Sectoral studies (sub-national) and case
studies.
The Impacts of Climate Change
on Coastal Zones
Sea-level rise, in combination with changes in the
frequency / intensity of extreme weather events is
expected to increase the flooding and inundation
of coastal areas.
As part of this work, the AdaptCost study has also
commissioned new specific sectoral work, notably
to run the DIVA model to assess coastal effects.
This briefing note reports on this review work and
summarises the new modelling analysis. Full
details are included in a sector report (Brown et
al, 2009) that is also available.
There are potential threats to coastal
environments and ecosystems including low-lying
coastal plains, islands, beaches, mangroves,
coastal wetlands and estuaries. There are also
potential threats to infrastructure, transportation,
agriculture and water resources within the coastal
zone, as well as tourism and provisioning services
(fishing, aquaculture and agriculture).
Background
Africa has a large and growing coastal population,
including a number of important coastal cities.
The direct impacts from sea-level rise include
inundation of low-lying areas, shoreline erosion,
coastal wetland loss, saltwater intrusion and
increased salinity in estuaries and coastal
aquifers, higher water tables and higher extreme
water levels leading to coastal flooding with
increased damage. Potential indirect impacts
include altered functions of coastal ecosystems
and impacts on human activities.
There are 33 countries with coastlines, and 7
adjacent island nations and territories1. The
continent’s coastline is estimated to be more than
38,000 km in length, with a further 7,000 km when
the adjacent island nations and territories are
included.
The coastal zone (defined as the land up to 10m
above sea level) around the continent varies in
widthfrom a few 100 metres (Red Sea area and
mountainous areas) to more than 100km (in the
Niger and Nile deltas).
This zone includes
mangrove forests and swamps, coral reefs, cliffs,
sand & mudflats, and tidal marshes, as well as
urban settlements.
Human-induced pressures on the coastal zone
(growing population, water abstraction, etc) are
also likely to exacerbate the effects of sea-level
rise – though these would also even in the
absence of climate change. These are important
in the context of future socio-economic change.
Africa has around 320 coastal cities (each with
more than 100,000 people) and nearly 56 million
people (2005 estimate) living in low elevation
(<10-m) coastal zones. There is also a growing
population and economy and strong trends of
urbanisation. Many of these coastal cities are also
important ports, which are key to national and
regional trade, imports and exports.
With a large and growing population in the coastal
zone and a low adaptive capacity due to low
national wealth and other development indicators,
most African countries appear to be highly
vulnerable. Indeed, this has been reported in
many previous assessments (e.g. IPCC AR42).
2
This is a particular concern for the large number
of rapidly growing coastal cities (see map below).
These adaptation strategies include coastal
defences (e.g. physical barriers to flooding and
coastal erosion such as dikes and flood barriers);
realignment of coastal defences landwards;
abandonment
(managed
or
unmanaged);
measures to reduce the energy of near-shore
waves and currents; coastal morphological
management; and resilience-building strategies.
Planned adaptation options to sea-level rise are
usually presented as one of three generic
approaches, i.e. retreat, accommodation or
protection. The types of options are summarised
below.
Table 1. The five major natural system effects
of relative sea-level rise, including examples
of possible adaptation responses
Natural System Effect
Inundation, flood and
storm damage
(includes surge (sea)
and backwater effect
(river)
Wetland loss (and
change)
Figure 1. African cities at risk of sea-level rise
Source: UN-HABITAT, 2008
There are also increased risks of coastal erosion
and flooding of low-lying coasts.
Erosion (direct and
indirect morphological
change)
However, compared to many other parts of the
world, the potential impacts of sea-level rise level
in Africa have received less study, particularly a
national and sub-national.
Saltwater Intrusion
a) surface waters
Adaptation
b) ground-water
In order to address the potential risks of climate
change to existing assets and people, some form
of protection is required for coastal environments,
such as cities, ports, deltas and agriculture areas.
Coastal protection to sea-level rise is often a
costly, but a straightforward way to overcome the
adverse impacts of climate change.
Rising water tables/
impeded drainage
Possible Adaptation
Responses
Dikes/surge barriers [P],
Building codes/floodwise
buildings [A],
Land use planning/hazard
delineation [A/R].
Land use planning [A/R],
Managed realignment/ forbid
hard defences [A/R],
Nourishment/sediment
management [P].
Coast defences [P],
Nourishment [P],
Building setbacks [R].
Saltwater intrusion barriers
[P],
Change water abstraction
[A/R].
Freshwater injection [P],
Change water abstraction
[A/R].
Upgrade drainage systems
[P],
Polders [P],
Change land use [A],
Land use planning/hazard
delineation [A/R].
[P] – Protection; [A] – Accommodation; and [R] –
Retreat
There are a large number of potential adaptation
options to address these risks, particularly for
protecting market sectors.
Source: Nichols et al (OECD, 20063).
3
Earlier studies
Niang-Diop (20057) estimated that the number of
people at risk from coastal flooding would
increase from 1 million in 1990 to 70 million in
2080, and the costs of adaptation to sea level rise
could amount to 5–10% of GDP in African coastal
countries.
Previous studies have estimated the potential
economic costs of sea level rise in Africa and
some estimates of the costs of adaptation.
Nicholls (20064) reported that the impacts of storm
surges in coastal areas could affect about 30
million people around the African Atlantic and
Indian Ocean coasts lives within a hazard zone
(i.e. the potentially exposed population), out of
which about 2 million people per year could
potentially be flooded in the 2020s. Due to the
occurrence of tropical storms, the study identified
Mozambique, Tanzania and Madagascar as being
particularly vulnerable countries to increased
flooding.
Ericson et al. (20068) considered six major African
deltas and relative sea-level rise as part of a
global study. The study estimated that about 1.4
million people could be displaced by present rates
of relative sea-level rise from 2000 to 2050< with
the vast bulk of these people (1.3.million) being in
the Nile delta.
Syvitski et al. (20099) identified the Nile and Niger
deltas as being the most threatened of the African
deltas due to subsidence and human interference,
with the Limpopo and Congo deltas being much
less threatened.
Nicholls et al. (20085) estimated the exposure of
the world largest port cities to coastal flooding due
to storm surge. Using a population criteria of one
million people in 2005, they identified 136 port
cities globally, of which 19 were in Africa. They
estimated African port city’s population exposure
at more than 2.6 million people in the coastal
floodplain (in 2005) with asset exposure of about
US$42 billion (in 2005. Alexandria (Egypt) and
Abidjan (Cote d’Ivoire) were identified amongst
the top twenty world port cities with high
population exposure to coastal flooding in 2005.
The AdaptCost DIVA Analysis
The AdaptCost study1 has investigated the
potential effects of sea level rise using the DIVA
(Dynamic Interactive Vulnerability Assessment)
model, an coastal integrated assessment model
that assesses biophysical and socio-economic
impact. Impacts were determined with and without
adaptation, so that the benefits and costs of
protection could be considered.
Further, the study assessed how these might
change in the future with climate change. Taking
high-end scenarios of socio-economic, climate
and non-climate trends for the 2070s, the total
population and assets exposed in Africa in the
nineteen major coastal cities was projected to
grow to 13.3 million people and US$998 billion of
assets, with exposure concentrated in Alexandria,
Lagos and Abidjan.
Some cities, such as
Mogadishu (Somalia) and Luanda (Angola) were
also considered to experience a rapid increase in
population and asset exposure posing significant
challenges for the future.
This section summarises the analysis.
technical report is also available
A full
A range of scenarios have been explored, with
three scenarios from the IPCC, plus a fourth
based on more recent literature which reports an
upper bound. This leads to a range of global sea
level rise from 0.17m to up to 1.26m from 1995 to
2100. These are shown in the figure below.
These changes have been assessed in
conjunction with three IPCC socio-economic
scenarios describing population growth and
density as well as future GDP (A1FI, A1B and
B1).
Dasgupta et al. (20096) ranked Egypt, Mauritania,
Tunisia, and Benin in the top ten most impacted
countries developing coastal countries world-wide
(out of a total of 84 countries considered) in terms
of the population potentially displaced due to a 1m
sea-level rise.
1
School of Civil Engineering and the Environment, University
of Southampton, UK: Sally Brown, Abiy Kebede and Robert
Nicholls
4
1.4
Rahmstorf
1.2
Sea level rise (m)
1
The values are higher for the A1F and more
extreme (Rahmstorf) scenarios, though much
lower for the B1 low range.
A1FI high-range
A1B mid-range
B1 low-range
0.8
The analysis also finds that as sea-level rises
more rapidly, coastal wetlands (saltmarshes,
mangroves, high and low unvegetated wetlands,
mangrove areas and coastal forest areas) will
decline in area. These losses have also been
expressed in monetary values.
0.6
0.4
0.2
0
1990
2000
2010
2020
2030
2040
2050
2060
2070
2080
2090
2100
Year
The study has estimated the economic costs
associated with migration, land loss due to
erosion and flooding, salinisation and costs
associated with sea and river floods. These reveal
significant economic costs, shown in the figure
below.
Figure 2. Sea Level Rise scenarios considered
The impacts were assessed in the years 2000,
2025, 2030, 2050 and 2075, focusing on (1)
People actually flooded, (2) Cumulative forced
migration, (3) Loss of wetland value, (4) Total
residual damage costs, and (5) Total adaptation
costs. However, a much wider set of impact
categories has been assessed. A full set of results
by country is included in the main technical report.
The summary results are presented below.
The estimated number of people flooded is shown
in the figure below. As an example, this indicates
that over two million people in Africa are
estimated to be flooded per year by the 2030,
rising to 5 million by 2050 (A1B mid-range
scenario). In the longer-term these risks increase
significantly with approximately 16 million people
will be flooded per year in 2100.
Figure 4. Total costs due sea-level rise and
socio-economic change from in Africa
Figure shows for the four sea-level scenarios studied with no
additional adaptation measures employed. 1995 prices.
For example, without adaptation, the total costs
for the A1B scenario are estimated at US$ 1.6
billion/year in 2030 (1995 prices), rising rapidly to
potentially $7.5 billion/year by 2050 (1995 prices).
In the longer-term for the A1B mid-range scenario
there is an estimated total damage cost of US$38
billion per year in 2100 (1995 prices). The values
are higher for the A1F and more extreme
(Rahmstorf) scenarios, though significantly lower
for the B1 low range.
Figure 3. Estimated number of people flooded
due sea-level rise and socio-economic change
from 2000 to 2100 in Africa
The results confirm that without adaptation, the
physical, human and economic impacts will be
significant. Moreover, it is important to note that
sea-level rise will not be the only factor shaping
Graph shows four sea-level scenarios studied with no
additional adaptation measures employed
5
Africa’s coast in the 21st Century. Other climate
change impacts such as increased storminess,
higher temperatures and reduced precipitation
also have immediate or secondary impacts of the
coast. These have not been considered in this
model, but could have important effects such as
more intense tropical storms hitting the coast of
East Africa (Mozambique, Tanzania and
Madagascar).
Finally,
there
are
many
anthropogenic factors influencing the coast, such
as the conversion of wetland to agriculture uses
or the reduction of sediment and water fluxes to
deltas,
often
combined
with
enhanced
subsidence. While these factors were not
considered here due to lack of data, they should
be considered in future studies.
Figure 5. Total residual costs due sea-level
rise and socio-economic change in Africa
Adaptation
Figure show four sea-level scenarios studied with adaptation
measures employed. 1995 prices.
The DIVA model has also considered the potential
costs of adaptation for coastal zones in Africa,
and the benefits of adaptation in reducing the
physical impacts and economic costs estimated
above. The DIVA model includes costs for two
types of adaptation options, to inundation and
coastal erosion, based on technical costs for an
increase in flood defence dike heights and
application of beach nourishment.
As an example, under the A1B scenario the
economic costs are reduce from $ 1.6 billion/year
in 2030 (1995 prices) to around $1 billion/year
with adaptation. Benefits in later years are much
greater with the reduction in economic costs in
2050 falling from $7.5 billion/year by 2050 (1995
prices) to $2.3 billion/year with adaptation. In the
longer-term the high damage costs in 2075 to
2100 are largely avoided.
With adaptation in place, the impacts and
economic costs above fall significantly.
The
model estimates that with optimal adaptation
(based on meeting acceptable coastal risk levels
for flooding, and based on a cost-benefit algorithm
for beach nourishment), the number of people
flooded per year is reduced significantly. As an
example, for the A1B mid scenario in 2030, the
number of people flooded reduces from 2 million
(no adaptation) to 200,000 – an order of
magnitude reduction. The numbers of people
flooded in later years actually reduces below this
level as adaptation becomes more effective.
The costs of adaptation to achieve these benefits
are relatively low in comparison, shown below.
Adaptation also reduces the economic costs
associated with migration, land loss due to
erosion and flooding, salinisation and costs
associated with sea and river floods. The resulting
economic costs – the residual impacts after
adaptation – are shown in the figure below.
Figure 6. Costs of adaptation due sea-level
rise and socio-economic change in Africa
Figure shows four sea-level scenarios studied employing a risk
based and cost-benefit approach. 1995 prices.
6
Under the A1B scenario, the costs of adaptation
are estimated at approximately $ 2 billion / year
over the time period 2030 - 2100. These costs
rise significantly with higher sea level scenarios,
up to $5 to 8 billion/year by 2100 under some of
the higher scenarios.
Nonetheless, coastal
protection appears to substantively reduce the
threat imposed by sea-level rise at a relatively low
cost, and in the analysis here, the benefits of
adaptation outweigh the costs.
global DIVA data set shows that economic costs
are much lower than for Asia.
For the A1B mid-range scenario by 2100 (a 43-cm
rise scenario) if there is no upgrade of defences
there are significant additional impacts estimated,
with 14 million people per year are at risk of
flooding, nearly 10 million people are at risk of
being displaced over the century (to 2100) and a
residual damage of nearly US$38 billion per year.
If beach nourishment and higher dikes are
introduced, these damages can be greatly
reduced and most importantly, forced population
displacement is nearly entirely avoided. The
incremental adaptation costs for Africa are
estimated at nearly US$2 billion per year.
However, even with adaptation, there are some
residual damages. Moreover, some additional
factors are important. Adaptation is likely to be
more costly and difficult than the headline
numbers above suggest. This reflects several
factors: (1) adaptation costs are partial, (2) there
is a large adaptation deficit, reflecting that Africa
is poorly adapted to today’s climate, and (3) there
is low adaptive capacity. Moreover, while it
possible and probably desirable to protect many
areas of coasts through adaptation, this does not
fully capture the full role of the coastline. Under
projected climate change and sea level rise,
coastal ecosystems will be threatened. These
habitats could be severely reduced or disappear
during the 21st century.
It is important to note that the adaptation will not
avoid all impacts, and there will be need to be
other investment such as port upgrade, measures
to counter salinisation, and extensive river dikes
in the coastally-influenced reaches of rivers.
Additionally, this infrastructure will require
maintenance which has not been costed here.
Lastly, there is the issue of the adaptation deficit
as many African countries are poorly adapted to
today’s climate. This is not taken account of in this
analysis, and the adaptation deficit implies more
investment will be required to meet the adaptation
needs of today before addressing future
challenges. The value of US$2 billion per year is
therefore a likely minimum adaptation cost.
Discussion
The results shown demonstrate that the higher
the rate of sea-level rise, the higher the impact
and economic costs for Africa. They also show
that the socio-economic scenarios are important
in determining impacts. This has been examined
in the main report through the consideration of a
scenario with socio-economic change only and no
climate change. This analysis shows future socioeconomic change (e.g. population growth) broadly
contributes around half the total economic costs
shown, i.e. even in the absence of climate
change, around half the increase in the economic
costs to coastal zones would occur.
It is also highlighted that as well as sufficient
funds, there is a need for greater capacity to
implement the necessary adaptation.
Analysis of Individual Countries
The full analysis has also produced DIVA results
for each individual coastal country in Africa.
These are included in the main report.
A
summary of key countries is included below
The falling population after 2050 under the A1/B1
scenario means that impacts grow less rapidly
from 2050 onwards than an alternative population
scenarios such as the A2 scenario, or a scenario
of net coastward migration.
A selection of the economic costs and costs of
adaptation are shown in the figures below,
showing values for 2030 and 2050. In each case,
the figures show socio-economic change (alone),
socio-economic and climate change before and
after adaptation, and the costs of adaptation.
As a continent, Africa appears highly vulnerable to
sea-level rise – though comparison against the
7
$200/yr
$200/yr
$200/yr
$100/yr
$100/yr
102 M
114 M
75 M
$100/yr
79 M
Libya
57 M
2030
65 M
2030
2030
2050
2050
Tunisia
2050
$200/yr
Morocco
97 M
$200/yr
$100/yr
49 M
$100/yr
78 M
Egypt
58 M
2050
2030
2050
2030
Senegal
$200/yr
Somalia
$200/yr
$100/yr
159 M
$100/yr
112 M
91 M
2030
2030
2050
2050
Guinea-bissau
$200/yr
Kenya
$200/yr
$100/yr
171 M
$100/yr
Guinea
51 M
78 M
42 M
47 M
2030
2050
$200/yr
2030
2050
Tanzania
$100/yr
Nigeria
$200/yr
$100/yr
15 M
2030
107 M
49 M
2050
136 M
Madagascar
2030
2050
$200/yr
140 M
156 M
2030
2050
$100/yr
Gabon
$200/yr
85 M
Mozambique
98 M
$100/yr
190 M
214 M
2030
2050
$200/yr
2030
South Africa
2050
$200/yr
148 M
159 M
$100/yr
2030
$100/yr
2050
Costs of adaptation per year ($Million/year) to sea level rise and socio-economic changes for
selected countries in Africa – A1B mid range scenario for 2030 and 2050.
Source produced by Paul Watkiss on basis of DIVA model results
Considering the relative ranking of countries in
absolute terms, the highest impacts for peoplebased impacts are Mozambique, Cameroon,
Tanzania, Morocco and Egypt. For economic
damages, the highest economic costs of sea level
rise are found in Algeria, Egypt, Morocco, South
Africa, Tunisia, Libya and Cameroon.
The highest adaptation costs (in the figure above)
vary with the time period, but generally occur in
Madagascar, Mozambique, Guinea, GuineaBissau, Nigeria, Somalia and South Africa. Note
that high impact costs and adaptation costs are
not automatically correlated.
8
Coastal protection to sea-level rise is often a
costly, but a straightforward way to overcome the
adverse impacts of climate change. In some
countries (for instance Mozambique, Nigeria) high
impacts result in high adaptation costs. Other
countries, for example Egypt, Tanzania and
Morocco, have high impacts but a lower
adaptation cost. Thus adaptation may be a
greater benefit to the latter countries rather than
the former.
the issue of adaptation in a local context and the
linkages with development, and considering more
realistic adaptation measures.
With a large and growing population in the coastal
zone and a low ability to adapt because of low
national wealth and adaptive capacity, most
countries around the continent appear to be highly
vulnerable.
Finally, these results focus on future climate
change, and there is also a need to consider
existing disaster risk reduction as a priority, as
well as to start planning for future change now.
While development can increase adaptive
capacity, there is also the potential for future
economic development to increase vulnerability,
for example if future population or economic
zones are located in areas that have high future
risks from sea level rise. This necessitates a
need for spatial planning. A key element of longterm planning will also be to ensure flexibility.
The analysis may also miss some of the more
important relative changes. For instance, Djibouti
has the tenth largest urban population as a
percentage of the country’s total population (52%)
located in the low elevation (<10m) coastal zone
(UN-HABITAT, 2008). As it is a small country, the
total costs are relatively low, yet on a country level
within, impacts may be high. Similar issues could
apply to Liberia and Senegal which also have a
high percentage of the total population living in a
low elevation coastal zone.
Note that the study has assumed a uniform rate of
sea-level rise but this will vary (for example, the
Mediterranean has experienced a lower rate of
sea-level rise in comparison to the global
average).
Other Aggregate Coastal Costs
of Adaptation for Africa
As highlighted in the OECD (2008) study, the
most extensive evidence base on the costs and
benefits of adaptation is in the coastal sector. This
also applies to Africa. There are a series of
studies which have been undertaken, many as
part of global assessments, which also include
analysis of coastal adaptation for Africa.
There is also a need to consider present problems
and the local context also needs to be considered.
Cameroon, Mauritania, Nigeria and Tanzania are
countries which experience relatively high rates of
subsidence, and even without climate change
they would experience slow relative sea-level rise
due to these non-climatic processes. Additionally,
local man-induced subsidence may increase rates
of relative sea-level rise, especially in deltas (for
example, the Nile delta).
1) UNFCCC Investment Flows
Work as part of the UNFCCC global study on the
costs of adaptation (200710) assessed coastal
zones using the DIVA model, and this provided
direct estimates of additional investment needed
for coastal infrastructure for Africa in 2030, and
assuming anticipation to 2080.
Additionally, higher temperatures and lower
precipitation would tend to reduce river levels
affecting river discharge and water availability.
Changes and intensification to farming practices
may mean that wetlands are at risk as they are
converted to agriculture and industrial use,
reducing a natural form of coastal defence.
Of the total global value for coastal adaptation
costs (of $11 billion), around 12-13% were in
Africa, with estimates of $1.2 to 1.3 billion/year in
2030. The more recent analysis with the DIVA
model here uses an updated model, and a wider
range of scenarios, but the central estimates in
the more recent analysis are higher.
Further work is required to better understand the
implications of sea-level rise for Africa in broad
sense, but also to move to national and subnational assessments. These can also address
9
2) IIED and Grantham Institute (2009):
Assessing the Costs of Adaptation to
Climate Change
Country Studies of the Costs of
Coastal Adaptation
The study has also reviewed the existing and
emerging national studies, many of which
consider the costs of adaptation for coastal zones.
The UNFCCC estimates were critiqued in
IIED/Grantham Institute study on assessing the
costs of adaptation (Parry et al11). This review
highlights that the coastal sector was only partially
covered and considered that the UNFCCC
estimates were a potential underestimate by
factor of 3 due to higher potential sea level rise.
Egypt (OECD, 2004)
A number of previous studies have identified
Egypt as at potential high risks from sea level rise.
Most recently, Dasgupta et al. (2009) ranked
Egypt as the first and second most impacted
developing country (of 84 developing coastal
nations) by 1m of sea-level rise in terms of
potential loss of agricultural land and population
displacement, respectively. With this magnitude of
sea-level rise, the nation was projected to
experience an estimated 6% decrease in GDP
resulting in the loss of 28,000 km 2 of agricultural
land (>13% of the national total), 25,000 km 2 of
urban area (>5% of the national total) and
24,000km2 of wetland loss (>6% of the national
total).
3) World Bank EACC
The Economics of Adaptation to Climate Change
(EACC) Study12 also estimated the costs of
adaptation, and also used the DIVA model looking
at a range of scenarios.
For the analysis, DIVA was extended to include a
sensitivity analysis of more intense tropical
storms. This influences adaptation costs only for
dikes. The maintenance costs of sea and river
dikes and port upgrades globally are also
computed outside DIVA. Port costs are based on
a strategy of continuously raising existing port
areas as sea levels rise.
The other extensive study was the OECD study
(200413) on the Egypt Nile delta estimated a total
loss of land, properties and revenues costing in
the range of US$30 billion for the city of
Alexandria under a 0.5m sea-level rise of ‘do
nothing’ scenario (inundating 30% of the city). The
same scenario estimated a total of US$2.9 billion
loss from land and property for Rosetta city and
US$2.2 billion loss in Port Said.
The resulting costs are shown below. These
imply higher costs than the DIVA model runs
above, due in part to the inclusion of these other
cateogories. However, it is also because the
medium run cited is for a Ramstorf A2 scenario,
rather than the A1B scenario above.
Annual cost of adaptation for coastal zone
protection for the medium sea-level rise
scenario, by region, 2010–50 ($ billions at 2005
prices, no discounting)
Time
period
Middle
East and
North
Africa
SubSaharan
Africa
Total
Africa
2010-19
1.0
3.2
4.2
2020-29
1.2
3.7
4.9
2030-39
1.3
4.2
5.5
2040-49
1.4
4.8
6.2
The study also investigated some adaptation
options to respond and ranked these. It
considered the costs and cost-effectiveness of
options. For Alexandria, the costs of options
ranged from $54 million for beach nourishment
and groins to $900 million for major land use
change. Beach nourishment, technical protection
(breakwaters, at a total cost of $468 million) and
integrated coastal zone management (at a total
cost of $ 550) had the highest cost-effectiveness.
Kenya (SEI, 2009)
Awuor et al, 200814 looked at Mombasa, and
reported that 17% of the city area could be
submerged by a sea-level rise of 30 cm. The
Source: World Bank, 2009.
10
study reported that improved irrigation planning
further inland and other land management
practices could be used for flood management
and reducing runoff into the ocean, which could
potentially contribute to reducing the impacts of
sea-level rise.
Benin of a rise in sea level. They used the
MAGICC IPCC scenario IS92a to construct
“Average”, “extreme” and “basic” sea level
scenarios.
They anticipate resulting coastal erosion, flooding
and salt penetration of water table. Additionally,
they project threats to road infrastructure &
residential districts, industrial & tourism sectors,
ecosystem damage and threats to fishing
communities. There is an adaptation plan being
developed which currently consists of two options
(awaiting funding). One option is to introduce
groynes which effectively transfer erosion along
coast, away from the city, in tandem with an offer
of compensation to those adversely affected. The
alternative is to move infrastructure, for example
building a new airport on higher ground.
The Regional Economics of Climate Change
Studies (RECCS) study for Kenya (SEI, 200915)
included a range of assessments, including
analysis of the potential impacts and costs of
adaptation for sea level rise. This used the DIVA
model outputs, consistent with the study
undertaken for AdaptCost above (Brown et al,
200916).
The analysis shows that coastal flooding from sea
level rise could affect 10,000 to 86,000 people a
year by 2030 (across the scenarios), as well as
leading to coastal wetland loss and coastal
erosion. The associated economic costs in 2030
are estimated to be $7 - 58 million per year
(current prices, no discounting) including flooding.
By 2050, these costs could increase to $31 - 113
million per year.
Nigeria
An earlier study (French et al., 199518) estimated
that 1m of sea-level rise by 2100, assuming no
human response, would threaten 18,000km2 and
3.2 million people would be at risk from flooding,
currently costing US$18 billion in Nigeria. These
estimates are based on 1992 population.
When adaptation was applied, the potential
impacts and economic costs above were
significantly reduced. The study reported that
adaptation has large potential benefits in reducing
coastal erosion and inundation. The number of
people that could be flooded is dramatically
reduced, and is one- two orders of magnitude
lower at 2,000 to 11,000 people per year in 2030
across the range of scenarios. The total costs are
also significantly reduced.
Protection by hard and soft measures would
reduce this risk, but would be costly. For instance,
protecting highly developed areas and oil
infrastructure from a 1m sea-level rise would,
alone, cost US$600-US$700 million. This cost,
spread over 50 year (a not unreasonable time
scale given sea-level rise projections, and design
guidelines for hard structures anticipating future
conditions), would cost 0.2-0.3% of the county’s
GDP. A 1m sea-level rise would make over 800
villages uninhabitable in the Niger delta, at a cost
of US$260million.
The cost of adaptation in 2030 is estimated at
$28-56 million / year depending on the sea level
rise scenario. These costs could rise to $80
million / year by 2050 and higher further in the
future. Note even with adaptation, there is some
residual damage. The finding is that coastal
protection appears to substantively reduce the
threat imposed by sea-level rise at a relatively low
cost, and in the analysis here, that the benefits of
adaptation far outweigh the costs.
Senegal
Another early study (Dennis et al., 199519)
estimated that in developed areas in Senegal,
accelerated erosion due to sea-level rise could
cost more than US$500-US$700 million (12-17%
of the country’s GDP at 1995 values) out of which
20-30% represents tourist facilities at risk. It is
also estimated that 110,000-180,000 people
(1.4% to 2.3% of the 1990 population) could be
Contonou, Benin
Dossou and Glehouenou-Dossou (200717)
identifeid the impact on the city of Cotonou in
11
displaced, the majority of which are located south
of the Cap Vert Peninsula.
Broadly speaking, results for some parameters
are of the same order of magnitude with previous
study estimates (e.g. with Nigeria,), while others
show significant differences (e.g. for land loss in
Senegal). Much of these differences will arise
from the difference in defining coasts and wetland
area and the level of aggregation in the analysis.
Protection, such as sea walls and beach
nourishment, was estimated to cost US$255US$845 million (0.7-2.2% of the country’s GDP)
over a fifty year period. Beach nourishment was a
favoured option, as this would help to maintain the
tourist industry, which accounts for around 3% of
the GDP.
There are also differences in the framework used
to derive adaptation costs. In DIVA, adaptation
costs are estimated based on a optimum methods
where resources are used where they are most
effective. Other studies may have used different
methods to calculate levels of protection or
different baselines, which may explain the
difference in costs. More assessment at the
country level is required to enhance our
understanding at this important scale of action.
Tanzania
A study of Dar es Salaam (Mwaipopo, 200020)
reported very little existing protection. Tourist
facilities – hotels and roads are partly protected
from erosion by groynes and a sea-wall. The cost
for building sea walls to protect important
vulnerable areas of the city against a 1-m rise in
sea level was estimated as US$ 337 million. The
study also projected that on average about 400m
landward retreat would occur in Dar es Sallam
under a 1-m sea-level rise, and a total of 247km2
land could be lost.
Forthcoming Studies
A large number of forthcoming studies will be
available, from the UNFCCC NEEDS project, the
UNDP
Investment
and
Financial
Flow
Assessments, and the World Bank EACC Country
Studies. Many of these include adaptation costs
for coastal zones. These will all emerge during
2010 and will provide a greater evidence base.
According to the Initial National Communication of
Tanania (2003), structures costing US$82 millions
in the vulnerable region of Dar es Sallam would
also be at risk for a 1-m rise in sea level.
The AdaptCost Project
South Africa
The AdaptCost Africa project, funded by United
Nations Environment Programme (UNEP) under
the Climate Change – Norway Partnership, is
producing a range of estimates of the financial
needs for climate adaptation in Africa using
different evidence lines. The study aims:
There has been extensive work on impacts and
adaptation to sea level rise in South Africa. This
includes the large study in the Western Cape
(Midgley et al, 200521)
There are studies developing adaptation plans
(Municipal Adaptation Plan) for Cape Town
(Mukheiber and Zievogel, 200722) which include
coastal erosion
 To
help African policymakers and the
international climate change community to
establish a collective target for financing
adaptation in Africa.
 To investigate estimates to adapt to climate
Most recently, there has been a series of sealevel rise adaptation studies (and costing) in
South Africa including local government
adaptation planning (Durban and Cape Town
change and improve
adaptation processes.
understanding
of
This briefing note was prepared by Paul Watkiss,
summarising the Coastal report by Sally Brown,
Abiy S. Kebede and Robert J. Nicholls of the
School of Civil Engineering and the Environment,
University of Southampton, Southampton, UK.
Synthesis of the National Studies
Comparing the aggregate estimates for Africa with
information from individual countries is difficult.
12
Footnotes and References
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13
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Annett Moehner, Mohamed El Raey, Declan Conway, Maarten
van Aalst, Marca Hagenstad and Joel Smith.
COM/ENV/EPOC/DCD/DAC(2004)1/FINA
14
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Sea-Level Rise and Impacts in Kenya, 2000 to 2100Sally
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21
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