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Climate change
Impacts and Strategies
Roberto Ferrise, Giacomo Trombi, Marco Moriondo & Marco Bindi
DiSAT – University of Florence
IFAD, Rome – IFAD – July, 24th 2008
Facing with Unprecedented Conditions
Temperature and CO2
World population
6.7 Billions
Food demand
High Temp. and CO2
Increase in Food
demand
Future Climate Projections
Extreme Events
Extreme events impact on
subsistence farming
• In the short/medium term (to 2025), rural poor
communities will be more strongly affected by
the impact of extreme events than the impacts
of changing means (Corbera et al.)
• Expected impacts on farming systems include:
-
Damage to crops at particular developmental stages
More difficult timing of agricultural operations
Damage to infrastructure
Reduced incentive to cultivate
Agro-ecosystem sensitivity to
climate now
General Constraints
Local Constraints
 Incoming solar radiation
 Temperature
 Water and nutrient availability
 Heat stresses
 Hails and storms
 Floods
Effect on agricultural crops
 Incoming solar radiation regulates photosynthesis processes
 Air temperature controls the duration of the growing period and other
processes linked with the accumulation of dry matter (i.e. leaf area expansion,
respiration)
 Rainfall and soil water availability affects the duration of growth (i.e leaf
area duration and photosynthetic efficiency)
Effect on animals (behaviour and production)
 metabolic processes (direct effect)
 forage quality and quantity (indirect effect)
Agro-ecosystem sensitivity to
Climate Change in the future
Climate change is expected to affect the agricultural production
acting on the main processes that regulate the different
components of the agro-ecosystem:
Components
Factors
CO2
Plant
Animal
Water
• Dry matter
accumulation
• Water use
• Forage yield
• Soil moisture
storage
Soil
Pest, diseases
Weeds
• Quality of host
biomass
• Crop competition
Temperature
Rainfall/Wind
• Duration of
growing season
• Dry matter accumulation
• Growth and
reproduction
• Peak irrigation
demand
• Soil salinisation
• Decomposition of
SOM
• Nutrient cycle
• Proliferation of
insect pests
•
• Health
• Water tables
• Wind and water erosion
• Diffusion of bacteria and fungi
Effectiveness of herbicide
1. Plants (I)
Enhanced CO2
Yield quantity: Plants will be directly
stimulated by enhanced concentrations
of CO2 leading:
 to larger and more vigorous plants
 to higher yields of total dry matter
(roots, shoots, leaves) and
harvestable product
* for a doubling CO2 [Source: Kindball, 1983]
Plants (II)
Changes of climatic parameters
 yields reduction of determinate crops,
i.e. cereals (shorter growing season)
 yield increase in indeterminate crops,
i.e. forage crops (longer growing
season)
Grain yield
(kg/ha)
9000
7000
5000
-2
0
2
4
6
Temperature change (°C)
Red Clover
8000
dry matter
(kg/ha)
Temperature. Higher temperature will
lead:
Winter wheat
11000
7000
6000
5000
-2
0
2
4
6
Temperature change (°C)
 water shortage that may be harmful
especially for crops like wheat,
sunflower, soybean
Grain yield
(kg/ha)
Rainfall. Lower rainfall in summer
season will lead:
Winter wheat
8500
8000
7500
7000
6500
6000
0.4
0.8
1.2
Relative rainfall
Combined effect of CC and
enhanced CO2 on crop production
• Yields of C3 crops (vegetable,
wheat and grapevine) generally
increase
• Yields of C4 crops and summer
crops generally decrease
• Inter-annual variability of crop
yields increase
• Yield quality may be affected
* UKTR model, decade 66-75, CO2 617;
(Source: Harrison and Butterfield,
1995)
2. Water availability
• Demand for water for
irrigation will rise increasing the
competition between agriculture
and urban as well as industrial
users of water
• Water tables will fall making the
practice of irrigation more
expensive
• Peak irrigation demands will
rise due to more severe heat
waves
• Risk of soils salinisation will
be increase for higher evaporation
3. Soil fertility and erosion
Higher air temperatures:
 speed up the natural decomposition of soil organic matter increasing
the rates of other soil processes (loss of fertility).
 accelerate the cycling of carbon, nitrogen, phosphorus, potassium
and sulphur, in the soil-plant-atmosphere system (enhancement of CO2
and N2O greenhouse gas emissions).
 increase the process of nitrogen fixation due to greater root
development
Changes in rainfall:
 increase the vulnerability to wind erosion suppressing both root
growth and decomposition of organic matter (lower summer
precipitations)
 increase soil erosion favouring run-off (higher frequency of high
intensity precipitation events)
4. Pests and Diseases
Depending on the specific interaction between pests/diseases/weeds,
and crops and climate there may be either an increase, a decrease or
no change in their effects on agricultural crops.
 e.g. Maize Streak Virus and Cassava Mosaic Virus in areas where rainfall
decreases, and sorghum headsmut (a fungal disease) in areas where
rainfall decreases.
Main drivers:
 higher temperature may be more favourable for the proliferation of
insect pests (longer growing seasons, higher possibility to survive during
winter time)
 enhanced CO2 may affect insect pests through amount and quality of the
host biomass (higher consumption rate of insect herbivores due to
reduced leaf N)
 altered wind patterns may change the spread of both wind-borne pests
and of bacteria and fungi
 increased frequency of floods may increase outbreaks of epizootic
diseases (i.e. African Horse Sickness)
5. Weeds
The differential effects of CO2 and climate changes on crops
and weeds will alter the weed-crop competitive interactions:
 higher CO2 concentration will stimulate photosynthesis
in C3 species and increase water use efficiency in both
C3 and C4 species
 changes in temperature, precipitation, wind and air
humidity may affect the effectiveness of herbicides
Prospected agro-ecosystem
response to CC
The response of agricultural production will be
extremely variegated and very crop and site dependent
Crop productivity is projected to increase slightly at mid- to high
latitudes for local mean temperature increases of up to 1-3°C
depending on the crop, and then decrease beyond that in some
regions.
At lower latitudes, especially seasonally dry and tropical
regions, crop productivity is projected to decrease for even small
local temperature increases (1-2°C), which would increase the
risk of hunger.
Prospected agro-ecosystem
response to CC
Increases in the frequency of droughts and floods are projected to
affect local crop production negatively, especially in subsistence
sectors at low latitudes.
Following climate change, crops are likely to shift their cultivation area to
meet their specific optimum climate conditions.
a. Cereals and seed crops
• The cultivation area will shift toward
higher latitudes or altitudes
• Drier conditions may lead to lower
yields
• Warmer temperatures will shorten
the length of growing season and
reduce yields
• Such an effect will be partially
counteracted by the increase in
CO2 concentration, which also will
lead to increased symbiotic nitrogen
fixation in pulses
b. Root and tuber crops
•Due to their large below ground sinks
for carbon are expected to show large
response to rising CO2
•Warming may reduce the growing
season in some species (potato) and
increase water requirements with
consequences for yields
•Other species (sugar beet) will benefit
from both warming and the increase
in CO2 concentrations
c. Pasture
•Yield is strictly dependent on the
projected rainfall pattern
•Primary production may increase in
temperate regions but decrease in
semiarid and tropical regions
•Species distribution and litter
composition will change (high CO2
levels may favor C3 plants over C4;
the opposite is expected under
associated temperature increases)
•Yields will differently affected by
weeds, pests, nutrient, competition for
resources.
Prospected impact on livestock
systems
Climate change may influence livestock
systems through different pathways:
Changes in availability and prices of grains for feeding (cereals,
pulses and other feed grains)
Changes in productivity of pastures and forage crops
Change in distribution of livestock diseases
Changes in animal health, growth, and reproduction (direct
effects of weather and extreme events)
Climate change may also affect the turn-over and losses of nutrients from
animal manure, both in houses, storages and in the field influencing the
availability of manure in organic farms
Vulnerable areas: a focus on
developing countries
• Developing countries will bear the brunt of climate
change impacts.
• Smallholder and subsistence agriculture are
particularly vulnerable, but to understand the impact of
CC on them it is necessary to:
– Recognize the complexity and high locationspecificity of their production systems
– Take into account non-climate stressors on rural
livelihoods.
– Consider the multiple-dimensions impact of climate
change on rural farming systems and livelihoods.
Vulnerable areas
LATIN AMERICA (I)
• Significant loss of biodiversity (through species extinctions in many
areas of tropical Latin America)
• Reduction of tropical forest due to:
• Replacement by savannah (eastern Amazonas, central and South
Mexico)
• Increased susceptibility to fire occurrences
• Land-use change (deforestation, agriculture expansion, financing
large scale project such as dams, roads, etc…)
• Agricultural lands are very likely to be subjected to desertification
and salinisation
• Changes in precipitation patterns are projected to affect water
availability for human consumption, agriculture and energy generation
Vulnerable areas
LATIN AMERICA (II)
Great variability of yield projections
(-30% Mexico to +5% in Argentina)
Rice yields is expected to decrease
after the year 2010
Soybean will increase yields when
CO2 effects are considered
A mean reduction of 10% in maize
yields could be expected by 2055
Land suitable for growing coffee in
Brazil and Mexico is expected to be
reduced
Heat stress and more dry soils may
reduce yields to 1/3 in the tropics
Vulnerable areas: ASIA
A northward shift of agricultural zones is likely (Tserendash et al., 2005).
Rice, maize and wheat production will decline due to the increased water
stress, arising from increasing temperature and reduction of rainy days
Yield of rice is expected to decrease by 10% for every 1°C increase in
growing season minimum temperature (Peng et al., 2004)
Aridity in Central and West Asia may reduce growth of grasslands and
increases bareness of the ground surface (Bou-Zeid and El-Fadel, 2002)
Agricultural irrigation demand in arid and semi-arid regions of Asia is
estimated to increase by at least 10% for an increase in temperature of
1°C (Fischer et al., 2002; Liu, 2002).
Vulnerable areas: AFRICA
Africa is probably the most vulnerable continent to climate change
and climate variability.
• CC will cause some countries to become at risk of water stress
exacerbating current water availability problems
• CC will be likely to reduce the length of growing season as well
as force large regions of marginal agriculture out of production.
Thus, agricultural production and food security (including access
to food) are likely to be severely compromised
Hotspots for vulnerability in Africa are: semiarid mixed rain-fed
crop-livestock systems in the Sahel, arid and semiarid grazing
systems in East Africa and mixed crop-livestock and highland
perennial crop systems in the Great Lakes Region. (ILRI, 2006)
CC impact on smallholder and
subsistence agriculture
• Negative impact on food and cash crops, due to the
increased likelihood of crop failure
• Impact on productivity and health of livestock, due to
increased diseases and mortality of livestock and/or
forced sales of livestock
• Livelihood impacts including sale of other assets,
indebtedness, out-migration, etc.
• Increased water stress
• Exacerbation of existing environmental problems
• Non-agricultural impacts (human health, ability to
provide labor for agriculture, tourism, etc.)
How to cope with Climate
Change
– Mitigation strategies of climate change (action
on the causes)
– Adaptation strategies to climate change
(alleviate the effects)
Tubiello, 2007
Mitigation
Mitigative effects
Measure
Examples
Cropland
management
Rice management
Grazing land
management/
pasture improvement
Net mitigation
(confidence)
Agree- Eviment
dence
CO2
CH4
N2O
+/-
+
+/-
**
**
Nutrient management
+
+
***
**
Tillage/residue management
+
+/-
**
**
+/-
*
*
Grazing intensity
+/-
+/-
Increased productivity (e.g.,
+
+/**
fertilization)
Species introduction
+
+/*
(including legumes)
Restoration of
Erosion control, organic
degraded lands amendments, nutrient
+
+/***
amendments
Livestock
Improved feeding practices
+
+
***
management
Specific agents and dietary
+
**
additives
+ denotes reduced emissions or enhanced removal (positive mitigative effect);
*
**
**
***
***
Main adaptive strategies
Economic and agronomic adaptation strategies will be important to
limit losses and exploit possible positive effects:
 The economic strategies are intended to render the agricultural
costs of climate change small by comparison with the overall
expansion of agricultural products
 The agronomic strategies intend to offset either partially or
completely the loss of productivity caused by climate change
Agronomic strategies
• short-term adjustment
• long-term adaptation
Main adaptive strategies:
Short Term (I)
Short-term adjustments may be considered as the
first defence tools against climate change and aims to
optimise production with minor system changes
through:
• The management of cropping systems
• The conservation of soil moisture
Main adaptive strategies:
Short Term (II)
The management of cropping systems considers:
 Changes in crop varieties (varieties with different thermal
requirements, varieties given less variable yields)
 Introduction of grater diversity of cultivars
 Changes in agronomic practices (sowing/planting dates)
 Changes in fertiliser and pesticide use
The conservation of soil moisture considers:
 The introduction of moisture conserving tillage methods
(minimum tillage, conservation tillage, stubble mulching, etc.)
 The management of irrigation (amount and efficiency)
Main adaptive strategies:
Long Term (I)
Long-term adaptation may overcome adversity caused by climate
change through major structural system changes:
 Changes in land allocation to optimise or stabilise production
(e.g. substituting crops with high inter-annual variability in
production (wheat) with crops with lower productivity but more
stable yields (pasture))
 Development of “designer-cultivars” to adapt to climate change
stresses (heat, water, pest and disease, etc.) much more rapidly
than it possibly today
 Crop substitution to conserve of soil moisture. (e.g. sorghum is
more tolerant of hot and dry conditions than maize)
Main adaptive strategies:
Long Term (II)
 Microclimate modification to improve water use efficiency in
agriculture (e.g. windbreaks, inter-cropping, multi-cropping
techniques)
 Changes in nutrient management to reflect the modified growth
and yield of crops, and also changes in the turn-over of nutrients
in soils, including losses.
 Changes in farming systems to maintain farms viable and
competitive (e.g. conversion of specialised farms in mixed farms
less sensitive to change in the environment)
Main adaptive strategies:
Spatial scale classification
Farm level
 Risk amelioration approaches (minimum disturbing techniques,
planting times and density, etc…)
 More opportunistic crops (environment, climate, market)
 Varieties with appropriate thermal time and vernalisation
requirements, resistance to new pests, etc…
Regional level
 Integrate climate change in regional planning (avoid stresses for
the environment caused by inappropriate actions)
National level
 Building resilient agricultural systems, able to cope with CC
(transition, communication, diversifying, training, water, etc…)
Coping with climate change in
poor rural farming systems
• Small farm sizes, low technology, low capitalization
and diverse non-climate stressor will tend to increase
the vulnerability of poor rural farmers.
• Smallholder and subsistence agriculture systems are
already characterized by constant adaptation to climate
variability, which is forming the basis of adaptation to
climate change.
• Typical resilience factors such as family labor, existing
patterns of diversification away from agriculture and
indigenous knowledge should not be underestimated
as important elements of adaptation strategies.
Main implications for related
sectors (I)
Food sector
Increased Population
Reduced water
availability
Higher/Wider
production needed
Changes in diet patterns (e.g.
food calorie intake in China &
India)
Food
production
Increased water need
for industry &
households
Increased water need
for irrigation
Main implications for related
sectors (II)
Forestry may be affected by drier and warmer conditions in the
Mediterranean region that could lead to more favourable
conditions for agro-forestry
Water resources may be interested by warmer and drier conditions
during summer that will enhance the demand for freshwater,
especially for agriculture and human consumption
Insurance my be affected by an altered frequency of extreme
weather events (e.g. storms, hails or floods) that will lead to lower
or higher damage costs
Other sectors that will contribute to rural income (e.g. ecotourism,
nature management, culture) may be affected directly or indirectly
by climate change.
Main uncertainties
 Those related to the possibility to include in the
assessments all the sources of uncertainties (e.g.
climate scenario, crop experiments, models and
spatialisation procedures)
 Those linked with unpredictable directions of future
social, economic, political and technical changes
(e.g. questions regarding population and
technological change are particularly relevant and
should be explored with upper and lower bounds of
possible projections)
Main unknowns (I)
 The impact of climate change on secondary factors of
agricultural production like soil, weeds, pests and
diseases
 The impact of increased surface receipts of UV-B
radiation on future agricultural performance and
agricultural response to climate change.
 The response of the quality of agricultural products to
atmospheric CO2 concentration increases, climate
change and exposure to atmospheric pollutants
Main unknowns (II)
 The impact of changes in mean climate and climate
variability on mean yield and yield variability
 The impact of increasing isolated and extreme events
(e.g. hail, strong winds, flooding and extreme high
temperatures) on agricultural production
 The response of crop production and farming systems in
sensitive or vulnerable regions (e.g. Asian and African
countries on the Mediterranean shore)
Recommendations (I)
• Encourage flexible land use (Resource: land).
• Encourage more prudent use of water (Resource: water)
• Improve the efficiency in food production and exploring
new biological fuels and ways to store more carbon in
trees and soils (Resource: energy)
• Assemble, preserve and characterise plant and animal
genes and research on alternative crops and animals
(Resource: genetic diversity)
Recommendations (II)
 Encourage research on adaptation, developing new
farming systems and developing alternative foods
(Resource: research capacity)
 Enhance national systems that disseminate information
on agricultural research and technology, and encourages
information exchange among farmers (Resource:
information systems)
 Promote the development of agricultural weather
information systems including the use of long-term
weather forecasts (Resource: management).
 Integrate environmental, agricultural and cultural
policies to preserve the heritage of rural environments
(Resource: culture).