Download Water and Climate Change

Water and Climate Change
in Africa
Raffaello Cervigni
The World Bank
Key Messages
1. The present: water management is a major
constraint to Africa’s development
2. The future: climate change will make those
constraint even more severe
3. The opportunity: climate change will increase
the urgency of reforms and investments that
would be important anyway
4. The challenge: we need both more knowledge,
and more resources
The present
Challenging natural conditions
High variability and low quantities for
much of the continent
Median rainfall and standard deviation USA - SSA
1200
Risk of
recurrent
drought
standard deviation
1000
SSA
USA
800
600
400
200
0
0
20
40
60
m edian rainfall %
80
100
Frequent extreme weather events
Hydrological variability has huge
impacts on poverty & livelihoods
Relationship holds even in diverse middle income economies
with substantial water storage infrastructure e.g. Morocco
Inability to smooth water availability
has multi-sectoral implications
• Under present conditions
(water storage, agricultural
development, transport
infrastructure etc), hydrologic
variability reduces potential
economic growth in Ethiopia by
38% and increases poverty by
25%
• A single drought over a 12-year
period will decrease average
GDP growth rates by 7-10%
Countries across continent already
facing different kinds of water crisis
Under-use in SSA, limited margins in North Africa
Proportion of Total Freshwater Resources Stored in Reservoirs
90
80
70
60
50
40
30
20
10
W
.E
ur
op
e
Au
s/
NZ
a
Am
er
ic
SS
A
No
rth
SA
S
NA
M
LA
C
EC
A
EA
P
0
142
Tanzania
370
Burkina Faso
800
788
900
South Africa
500
492
600
Morocco
363
300
Namibia
307
400
Nigeria
139
0
Algeria
114
200
Kenya
47
11
100
Ethiopia
Lesotho
storage / capita
Water storage south of the Sahara
is woefully under-developed
700
Water
management
in Africa is
particularly
challenging,
because
international
river basins
are
predominant
The future
What is expected to change?
• Temperature:
– Expected to increase 2°- 6°C (over next
century) with greatest impact over the semiarid margins of the Sahara and central
southern Africa and least in equatorial
latitudes and coastal environments.
• Precipitation:
– Projected future changes in mean seasonal
rainfall in Africa are less well defined.
Severe, but diverse impacts
Percent change in run-off: multi-model average for the winter and summer precipitation (A1B SRES scenario)
Reduction
of 20 to 30% by 2050
Source: Milly et al (2005),
published in Nature
Increase
of 20 to 30%
by 2050
In water-scarce countries,
agriculture will change
• Rain-fed agriculture will become less reliable
• Water allocations to agriculture will fall significantly
– Urban use will take priority and urban populations
growing
• New irrigation schemes will have to be designed for
lower water availability
• Less surface water will encourage users to use
groundwater
• Controlling this is a highly complex institutional challenge
• Reduced water availability in agriculture increases
dependence on trade (high value crops for export,
import of staples)
The opportunity
When countries can smooth consumption,
agriculture becomes much more stable
40
Agriculture, value added (Annual % growth)
Ethiopia
Egypt
30
Sudan
20
10
0
1982
1984
1986
1988
1990
1992
-10
-20
-30
Year
1994
1996
1998
2000
2002
Actions needed will become all the
more important
• Improved
monitoring,
assessment of water
balance
• Improved planning
and allocation
processes, including
internationally
• Strengthening
institutions to
manage water
• Investments
There will be no substitute for reform
• It will become all the
more important to review
– Policies that promote
activities that are
particularly vulnerable to
precipitation
• E.g. subsidies for rainfed
wheat production in North
Africa
– Plans for new infrastructure
where institutions are not
yet ready to generate the
potential benefits
The challenge
Improving knowledge
for better planning
Change in rainfall
(m m /year)
ECHAM4
2040-2069
HADCM2
2040-2069
CSIRO
2040-2069
NCAR
2010-2049
CCSR
2040-2069
200
100
0
-100
-200
CGCM1
2040-2069
GFDL
2010-2049
Mobilizing resources for storage
management
Years needed at 10% current GDP investment per year to reach
South Africa Standard
Ethiopia
Ghana
Tanzania
Uganda
Lesotho
Senegal
Nigeria
Kenya
Burkina Faso
Namibia
Algeria
Morocco
0
10
20
30
40
50
60
70
80
Climate change can be an
opportunity
• The door may be
opening, provided . . . .
• Political attention
internationally
• Consensus at national
and local level