Climate change

Impacts and Strategies

Roberto Ferrise, Giacomo Trombi, Marco Moriondo & Marco Bindi

DiSAT – University of Florence

IFAD, Rome – IFAD – July, 24th 2008

High Temp. and CO2

6.7 Billions

Temperature and CO2 World population

Increase in Fooddemand

Food demand

Facing with Unprecedented Conditions

Extreme Events

Future Climate Projections

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

General Constraints Incoming solar radiation Temperature Water and nutrient availability

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 now

Local Constraints Heat stresses Hails and storms Floods

Climate change is expected to affect the agricultural production acting on the main processes that regulate the different components of the agro-ecosystem:

Agro-ecosystem sensitivity to Climate Change in the future

Components Factors

CO2 Temperature Rainfall/Wind

Plant • Dry matter accumulation

• Water use

• Duration of growing season

• Dry matter accumulation

Animal • Forage yield • Growth and reproduction

• Health

Water • Soil moisture storage

• Peak irrigation demand

• Soil salinisation

• Water tables

Soil • Decomposition of SOM

• Nutrient cycle

• Wind and water erosion

Pest, diseases • Quality of host biomass

• Proliferation of insect pests

• Diffusion of bacteria and fungi

Weeds • Crop competition • Effectiveness of herbicide

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]

1. Plants (I)

Changes of climatic parameters

Temperature. Higher temperature will lead:

yields reduction of determinate crops, i.e. cereals (shorter growing season)

yield increase in indeterminate crops, i.e. forage crops (longer growing

season)

Rainfall. Lower rainfall in summer season will lead:

water shortage that may be harmful especially for crops like wheat, sunflower, soybean

Winter wheat

5000

7000

9000

11000

-2 0 2 4 6

Temperature change (°C)

Grain

yie

ld

(kg/ha)

Winter wheat

600065007000750080008500

0.4 0.8 1.2

Relat ive rainf all

Grain

yie

ld

(kg/ha)

Red Clover

5000

6000

7000

8000

-2 0 2 4 6

Temperature change (°C)

dry m

atter

(kg/ha)

Plants (II)

* UKTR model, decade 66-75, CO2 617; (Source: Harrison and Butterfield,

1995)

• 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

Combined effect of CC and enhanced CO2 on crop production

• 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

2. Water availability

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)

3. Soil fertility and erosion

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)

4. Pests and Diseases

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

5. Weeds

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 highlatitudes for local mean temperature increases of up to 1-3°Cdepending on the crop, and then decrease beyond that in someregions.

At lower latitudes, especially seasonally dry and tropicalregions, crop productivity is projected to decrease for even smalllocal temperature increases (1-2°C), which would increase therisk of hunger.

Prospected agro-ecosystem response to CC

Increases in the frequency of droughts and floods are projected toaffect local crop production negatively, especially in subsistencesectors at low latitudes.

Following climate change, crops are likely to shift their cultivation area to meet their specific optimum climate conditions.

Prospected agro-ecosystem response to CC

• 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

a. Cereals and seed 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

b. Root and tuber crops

•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.

c. Pasture

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

Prospected impact on livestock systems

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 location-

specificity 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 areasLATIN 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

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 areasLATIN AMERICA (II)

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: ASIA

Vulnerable areas: AFRICAAfrica 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

Mitigative effects Net mitigation (confidence)

Measure Examples CO2 CH4 N2O Agree-ment

Evi-dence

Cropland management

Rice management +/- + +/- ** **

Nutrient management + + *** **

Tillage/residue management + +/- ** **

Grazing land management/ pasture im-provement

Grazing intensity +/- +/- +/- * *

Increased productivity (e.g., fertilization)

+ +/- ** *

Species introduction (including legumes)

+ +/- * **

Restoration of degraded lands

Erosion control, organic amendments, nutrient amendments

+ +/- *** **

Livestock management

Improved feeding practices + + *** ***

Specific agents and dietary additives

+ ** ***

+ denotes reduced emissions or enhanced removal (positive mitigative effect);

Mitigation

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 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 (I)

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:Short Term (II)

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 (I)

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:Long Term (II)

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.

Food sector

Main implications for related sectors (I)

Increased Population

Changes in diet patterns (e.g. food calorie intake in China &

India)

Increased water need for irrigation

Higher/Wider production needed

Increased water need for industry & households

Reduced water availability Food

production

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 implications for related sectors (II)

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 uncertainties

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 (I)

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)

Main unknowns (II)

• 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 (I)

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).

Recommendations (II)