Climate change in africa impacts on agriculture
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Climate Change in Africa: Impacts on Agriculture Prof. John Prof. John Sweeney, Sweeney, Department Department of of Geography Geography NUI MAYNOOTH Ollscoil na Éireann Má Nuad Food Security & Climate Change in Africa – A community solution. 20 th May 2010
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Presentation by Mr. Eric Yao, co-ordinator of The Africa Centre, Dublin, and a farmer in Ghana, on the effects that a changing climate has had on his business.
Transcript of Climate change in africa impacts on agriculture
Climate Change in Africa: Impacts on Agriculture
Prof. John Prof. John Sweeney,Sweeney,
Department of Department of GeographyGeography
NUI MAYNOOTHOllscoil na Éireann Má Nuad
Food Security & Climate Change in Africa – A community solution. 20th May 2010
Thomas Malthus on Population and Resources
Malthusian Theory of PopulationMalthus argued that population increased geometrically while resources increased only arithmetically.
He predicted that, eventually, population growth would outstrip resources and calamities (starvation, diseases, wars) would produce a population crash which would bring population back to balance supply of resources.
The Green Revolution
First green revolution(developed countries)First green revolution(developed countries)
Second green revolution(developing countries)
Second green revolution(developing countries)
Major International agricultural research centres and seed banksMajor International agricultural research centres and seed banks
Heavier heads required:more fertilizer, water, hybrids with shorter stalks (to prevent lodging)
Higher density plantings required:more fertilizer, constant water, hybrids with smaller root system
More plantings per year required:more fertilizer, year round water, pesticides
2,000
1,500
1,000
500
0
Gra
in p
rod
uct
ion
(mill
ion
s o
f to
ns)
1950 1960 1970 1980 1990 2000 2010
Total World Grain Production
400
350
300
250
150
Per
cap
ita
gra
in p
rod
uct
ion
(kilo
gra
ms
per
per
son
)
1950 1960 1970 1980 1990 2000 2010
Per Capita World Grain Production
200
Population Growth2000-2080
Source: Lutz et al., 2001
Africa by 2050 will have a population equivalent to that of Europe, Australasia and the Americas
combined
Global Food production
• Yields still increasing but rate declining• 800 million undernourished (hungry) with
no money to buy available food• 3 billion malnourished• Many countries not self-sufficient in food• Total calorie production has kept pace
with population growth thanks to oil crops, but…
• per capita grain production has fallen for past two decades (380 to 330 kgs/person)
Compounding Impacts of Climate Variability
Climate variability has huge impacts on poverty & livelihoods
Correlation between Rainfall and Real GDP growth in Zimbabwe
-10.0
-5.0
0.0
5.0
10.0
15.0
20.0
25.0
Years
-4.0
-3.0
-2.0
-1.0
0.0
1.0
2.0
3.0
4.0
Real GDP growth (%)
Variability in Rainfall (Meter)
Relationship holds even in diverse middle income economies with substantial water storage infrastructure e.g. Morocco
(Source: Le Houérou et al, 2006)
Rainfall trends in the Sahel
1950-1959 (mm)
1970-1984 (mm)
Atbara 92 54
Khartoum 178 116
Agadez 210 97
Tombouctou 241 147
Global Food production needs to double to meet the needs of an additional 3 billion people in the next 30 years
Climate change is projected to decrease agricultural productivity in Africa for almost any amount of warming
Assessing Agricultural Impacts requires two sometimes contradictory effects to
be considered
• The (Direct) beneficial effect to most plants of having more CO2 in the atmosphere to aid photosynthesis
• The (Indirect) effect, positive or negative, which a particular change of climate may have on the productive capacity of the plant itself.
C3 and C4 Plants• C3 Plants
– Wheat, Rice, Barley, Oats, Pea, Bean,Potato– Soya Bean, Coconut, Banana, Cassava, Sugar
Beet
• C4 Plants– Maize, sorghum, Millet,Sugar cane– Most grasses
C3 crops outperform C4 crops with higher CO2 concentrations
Crop yield response to temperature change
IPCC WG-II (2007)
Without adaptationWith adaptation
Cereal production in developed and developing countries
Projected changes in crop yields
Suitability for rainfed cereals 1961-90
Suitability for rainfed cereals 2080’s A1FI
Suitability for coffee in Uganda
IPCC WG-I (2007)
Indirect Effects
• As well as stimulating the crop directly, the increases in CO2 will also stimulate weed growth.
• Many weeds are C3 plants
Indirect Effects
• Temperature increases may extend the range of some pests currently limited by temperature, especially at high latitudes
• No of generations per year may increase
• Earlier appearance in the growing season
Vulnerability to climate change (A2) in 2050
Without adaptation
With adaptation
0
20
40
60
80
80 100 120 140 160 180 200
Index of Food Supply / Food Required
% u
nd
ern
ou
rish
ed
0
200
400
600
800
1000
1969-71 1979-81 1990-92 1997-99
mill
ion
peo
ple
Latin America &Carribean
South Asia
East Asia
Near East & North Africa
Sub-Saharan Africa
The State of Food
Insecurity
(Source: FAO, 2001)
0
100
200
300
400
500
600
2000 2010 2020 2030 2040 2050 2060 2070 2080
Po
eple
at
Ris
k o
f H
un
ger
(m
illi
on
s)
A2
B2
B1
A1
0
50
100
150
200
250
300
350
2000 2010 2020 2030 2040 2050 2060 2070 2080
Po
eple
at
Ris
k o
f H
un
ger
(m
illi
on
s)
A2
B2
B1
A1
Source: Fischer et al., 2002
Number of People at Risk
of Hunger
projected for different IPCC
economic development paths
AFRICA
SOUTH, SOUTHEAST and
EAST ASIA
What needs to be done
• Improve our understanding of the effects of climate change on specific cropping systems and the possibilities for adapting to change
• Improve institutional capacities (research, advisory systems, on-farm experimentation, farmer education)
• Investment in the development of improved seeds and cultivars in terms of tolerance to high temperatures and drought
• Improved strategies to tackle biological constraints including those pertaining to pests and diseases
• Improve efficiency of irrigation systems• Improve strategies for soil and land use management systems to make them
more resilient to flooding and droughts• Ensure that sufficient financial and human capital is available to make timely
investments in adaptation and overcome recognised socio-economic-constraints.
Climate effects on crop yields
Yield
ClimateTemperature + Rainfall
Growthduration
Wateravailability
Resource useefficiencies
SoilWeeds,Pests, diseasesFreshwater
Adaptation
Yield
ClimateTemperature + Rainfall
Growthduration
Wateravailability
Resource useefficiencies
SoilWeeds,Pests, diseasesFreshwater
Microclimatemodification
Changecrops Irrigation Soil
managementCropping systemdiversity
Teleconnections in Sahel
Greenhouse gas emissions
-50
-25
0
25
50
75
100
125
150
0.01 0.1 1 10
CO2 emissions per capita (tons Carbon; logarithmic scale)
% c
han
ge
pro
du
ctio
n p
ote
nti
al
Developing
Developed
Transition
Climate Change Impacts and Carbon Dioxide EmissionsECHAM4, 2080s
Fairness and Equity?
Greenhouse gas emissions since 1950:
75% from developed countries, 25% from developing countries
Pro
bab
ility
of
occ
urr
ence
Average HotCold Very Hot
More record hot
weather
More record hot
weather
More record hot
weatherMore
record cold weather
- “mean” effect
- “variance” effectcombined “mean + variance”
Climate change effects on extreme temperatures
Current climateFuture climate
After Timbal,B and McAvaney, B.
