Transcript (CS 755 CLIMATE, AGRICULTURE AND ENVIRONMENT)

CS 755: CLIMATE, AGRICULTURE
AND ENVIRONMENT
BY
REV. PROF. MENSAH BONSU
COURSE CONTENT
Introduction to Climatology
• Differentiating between weather and climate
• Partitioning the Atmosphere
• Climatic elements and their usefulness
• Solar energy and air temperature
• The earth inclination and temperature
variation
• The lapse rate and temperature inversion
COURSE CONTENT
Introduction to Climatology
• Air pressure and winds
 pressure gradient force
 The convection system
 Land and sea breezes
 Mountain and valley breezes
Cariolis effect
 Frictional effect
• Global air circulation pattern
COURSE CONTENT
Introduction to Climatology
• Ocean currents and their effects on
precipitation
• Moisture in the atmosphere
• Air masses and storms
• Climate regions of the world
INTRODUCTION TO CLIMATOLOGY
• Weather: State of the atmosphere at a given
time and place e.g. temperature, wind and
precipitation.
• Climate: Long-term average weather
conditions in a place or region or trends in
weather data that have been accumulated
over an extended period of time e.g. tropical
climate, sub-tropical climate etc.
PARTITIONING THE ATMOSPHERE
• Troposphere is the lowest layer of the earth’s
atmosphere; it extends about 10 km above
ground.
• Stratosphere is the next layer of the earth’s
atmosphere after troposphere; it extends
approximately 10 to 24 km above the ground.
• The imaginary boundary separating the
troposphere and the stratosphere is called
tropopause.
CLIMATIC ELEMENTS AND THEIR INFLUENCE
ON HUMAN EXISTENCE (USEFULNESS)
• The troposphere contains all the air, clouds
and precipitation of the earth.
• The earth climatic differences make us
understand the way people use the land.
• Climate is key to understanding the
distribution of world population.
LECTURE 2
DESCRIPTION OF ELEMENTS CONSTITUTING
WEATHER CONDITIONS
Solar energy and air temperature
The intensity and duration of solar radiation at
any given place vary and are controlled by:
• The angle at which the sun’s rays strike the
earth
• The number of daylight hours
DESCRIPTION OF ELEMENTS CONSTITUTING
WEATHER CONDITIONS
The temperature variation of the earth and the earth’s
inclination
• The axis of the earth connecting the north and the south
poles is tilted about 23.5° from the perpendicular.
• If the earth were not tilted in this way, the solar radiation
received at a given latitude would not vary during the
course of the year.
• When the Northern Hemisphere is tilted directly toward
the sun, the sun’s vertical rays are felt 23.5 °N latitude
(Tropic of Cancer). This position occurs in June 21, and we
have summer for the Northern Hemisphere, and winter
for the Southern Hemisphere.
DESCRIPTION OF ELEMENTS CONSTITUTING
WEATHER CONDITIONS
The temperature variation of the earth and the
earth’s inclination
• About December 21, the vertical rays of the sun
strike near 23.5 °S latitude (Tropic of Capricorn); it is
the beginning of summer in the Southern
Hemisphere and onset of winter in the Northern
Hemisphere.
• The tilt of the earth makes the length of days and
nights vary during the year. One half of the earth is
always illuminated by the sun at any particular time.
It is only at the equator that there is light for 12
hours each day of the year.
DESCRIPTION OF ELEMENTS CONSTITUTING
WEATHER CONDITIONS
The Lapse rate and temperature inversion
• Within the troposphere, temperatures are usually
warmest at the earth’s surface and decrease as
elevation increase. This rate of change of
temperature with altitude in the troposphere is
called lapse rate, and the average is about 6.4 °C per
1000 meters.
• Sometimes the earth radiation is so rapid that it
causes temperatures to be higher above the earth
surface than at the surface itself. This particular
condition is called temperature inversion.
DESCRIPTION OF ELEMENTS CONSTITUTING
WEATHER CONDITIONS
Importance of temperature inversion
Warm air at the surface may be blocked by
relatively warmer air above the surface due to
temperature inversion. If the trapped surface air,
which is relatively cooler, is filled with automobile
exhaust emissions or smoke, a serious smog
condition may develop close to the surface.
Smog = smoke + fog
AIR PRESSURE AND WINDS
• There is a drop in atmospheric pressure when
air heats up and a rise in pressure when air
cools down.
• The lighter air moves to the top while the
heavier air moves to the bottom, causing the
heavier air to spread horizontally.
• Therefore air moves from heavy (cold) air
locations (high air pressure) to light (warm) air
locations (low air pressure).
• The greater the differences in air pressure
between places, the stronger the wind.
PRESSURE GRADIENT FORCE
• The differences in the nature of the earth’s
surface, e.g. water and green forest, may cause
zones of high and low pressures to develop.
• Pressure differences between areas create
pressure gradient force, which causes air to blow
from an area of high pressure toward an area of
low pressure.
• Heavy air stays close to the earth surface and
forces the upward movement of warm (light) air,
producing winds. The velocity or speed of the
wind is directly proportional to the pressure
differences.
PRESSURE GRADIENT FORCE
• If distances between high and low pressure zones
are short, pressure gradients are steep and strong
wind velocities develop.
• When zones of different pressures are far apart,
the pressure gradients are not great, and gentle
air movements occur.
THE CONVECTION SYSTEM
Warm air rises as cool air descends. The circulating
motion of ascending warm air and descending cool
air is known as Convection.
LAND AND SEA BREEZES
• One example of a convectional system is Land
and Sea Breezes.
• Evaporative cooling (latent heat of vaporization),
causes the water surface to be cooler than the
Land surface during the day
• The warmer air over the land surface rises
vertically (low pressure), and the cooler air from
the water surface (high pressure) flows to take
the place of the ascending warm air and a cooling
breeze results on Land – Sea Breeze
• During the night, the land cools faster than the
water surface and the opposite occurs, that is,
Land Breeze toward the sea.
MOUNTAIN AND VALLEY BREEZES (i.e.
TOPOGRAPHIC WIND EFFECT – ANABATIC WIND)
• During the day, the air above the slope of the
valley will be heated to a higher temperature
than that of the center of the valley. The warm
air above the slope rises while the cooler air of
the valley moves to the upslope to give rise to
valley breeze. During the night, mountain
breezes occur. The air of the mountain slopes
cools and descends to the valley. Thus
bringing cool breeze to the valley – mountain
breeze.
CARIOLIS EFFECT
As winds move from high pressure zone to low
pressure zone, they tend to be deflected toward the
right in the Northern Hemisphere and toward the
left in the Southern Hemisphere. This deflection is
called cariolis effect.
The cariolis effect and the pressure gradient force
produce spirals rather than straight patterns of
wind.
Spiral of wind characterize the earth’s air circulation
system of many storms’.
FRICTIONAL EFFECT
• The movement of wind is slowed down by the
frictional drag of the earth’s surface.
• The effect is strongest at the surface and
declines with elevation until it becomes
ineffective at about 1,500 meters above the
surface.
• The frictional effect decreases the magnitude
of wind speed and changes the direction of
wind flow.
THE GLOBAL AIR CIRCULATION PATTERN
Sub-tropical high pressure zone
• Because of solar heating, the air in the equatorial
zone is warm (lighter) and tends to move away
from the equatorial low pressure in both the
northerly and southerly directions.
• As the equatorial air rises, it cools and eventually
becomes dense. The lighter air near the surface
cannot support the cool, heavy air.
• The heavy air falls, forming surface zones of high
pressure called sub-tropical high pressure, which
are located 30 °N and 30 °S of the equator.
NORTH-EAST TRADES IN THE TROPICS
When the cooled air reaches the earth surface,
the part that moves in the northerly direction
undergoes cariolis effect in the Northern
Hemisphere to give belts of wind called Northeast trades in the tropics.
SOUTH WESTERLIES IN THE MID-LATITUDES
The part of the cooled air that moves in the
southerly direction also undergoes cariolis effect
to give rise to south-westerlies in the midlatitudes.
SUB POLAR LOW PRESSURE ZONE
A series of ascending air cells also exists over the
oceans to the north of the westerlies called sub
polar low pressure zone. These areas tend to be
cool and rainy.
THE POLAR HIGH
• The polar easterlies connect the sub-polar low
areas to the polar high areas.
• the general global air circulation pattern is
modified by local wind conditions.
OCEAN CURRENTS AND THEIR EFFECT ON
PRECIPITATION
• The winds of the world set ocean currents in
motion.
• Differences in density of water cause water to
move from a zone of high density to a zone of
low density.
• Thus wind direction and differences in density
cause water to move in various paths from
one part of the ocean to another
OCEAN CURRENTS AND THEIR EFFECT ON
PRECIPITATION
• Cold ocean currents near land cause the air
just above the water to be cold while the air
above this cold zone is warm. This condition
prevents convection effects, thus denying
moisture to nearby land. That is why coastal
deserts of the world border cold ocean
currents.
• Warm ocean currents bring moisture to the
adjacent land area, especially when prevailing
winds are landward.
MOISTURE IN THE ATMOSPHERE
Cloud Formation
• Descending air in the high pressure zones
yields cloudless skies.
• As warm, moist air rises, clouds form. This
kind of cloud formation that often
accompanies heavy rain is the
CUMULONIMBUS.
EL-NINO
• El-nino condition prevails as the result of the
interaction of the atmospheric pressure and
ocean temperature.
• Under normal circumstances, in the south
pacific ocean, trade winds blow warm surface
water west-ward and allow cold water to
come to the surface along the South American
Coast. This condition maintains the contrast in
water temperature.
EL-NINO
• But when a condition called the Southern
Oscillation occurs, there is warming in the
eastern pacific, enhancing the usual
temperature contrasts between the equator
and the poles. Atmospheric pressure rises
near Australia, the wind falters and El-nino is
created off the coast of South America.
• The greater the temperature disparity
combined with moisture availability from the
pacific ocean, the more severe the weather.
AIR MASSES AND STORMS
• Air masses are large bodies of air with similar
temperature and humidity characteristics
throughout. They form from a source region.
• When two different air masses come into
contact, a front develops and the possibility
of storms developing is created.
• If the contrasts in temperature and humidity
are sufficiently great, or if the touching air
masses are moving in opposite direction,
waves might develop in the front.
AIR MASSES AND STORMS
• As the waves enlarge, cooler air may move along
the surface, while warm air moves up and over
the cold air, the rising warm air creates a low
pressure centre and precipitation accompanied
by winds develops into a storm or cyclone.
• Tropical cyclone or hurricane begins in a low
pressure zone over warm waters, usually in the
Northern Hemisphere. In the developing
hurricane, the warm, moist air at the surface
rises, which helps to suck up air resulting in the
formation of thick cumulonimbus clouds.
CLIMATE TYPES AND THEIR LOCATIONS
• TROPICAL
Associated with earth areas lying between the
Tropic of cancer in the North of the equator and
the Tropic of Capricorn in the South of the
Equator.
• DRYLAND
Associated with areas in the interior of
continents where mountains block west winds,
or inlands far from the reaches of moist tropical
air.
CLIMATE TYPES AND THEIR LOCATIONS
• HUMID MID-LATITUDE
Mountain ranges, warm or cold ocean currents,
particularly land-water configuration bring
about variations in the middle latitudes.
• SUBARCTIC AND ARCTIC
Located toward northern areas and into the
interior parts of the North America and Eurasian
Landmasses.
CLIMATE REGIONS OF THE WORLD
The two most important elements that differentiate
weather conditions are temperature and precipitation.
CLIMATE TYPE
TEMPERATURE AND PRECIPITATION
TROPICAL
• Tropical Rainforest
• constant high
• Savanna
• High
temperatures
• Rainfall: heavy all year (convectional)
• High amount of cloud cover
• High humidity
temperatures
• Rainfall: heavy in summer (convectional)
• Dry in winter
• Monsoon: highest temperature just before
rainy season
CLIMATE TYPE
TEMPERATURE AND PRECIPITATION
SEMI-DESERT AND DRYLAND
• Hot Deserts
• Extremely high temperatures in
summer, warm winters
• Very little rainfall
• Low humidity
• Steppe and Desert
• Warm to hot summers
• Cold winters
• Convectional rainfall in summer
• Some frontal snowfall in winter
CLIMATE TYPE
TEMPERATURE AND PRECIPITATION
HUMID MID-LATITUDE
• Mediterranean
•
•
•
•
•
• Humid Subtropical
• Hot summers
• Mild winters
• Convectional showers in summer
• Frontal precipitation in winter
• Marine West Coast
• Westerly winds year round
• Mild summers
• Cool to cold winters
• Low rainfall in summer
• Frontal rainfall in winter
• Humid Continental
• Hot to mild summers
• Cool to very cold winters
•Convectional showers in summer
• Frontal rainfall in winter
Warm to hot summers
Mild to cool winters
Dry summer
Frontal precipitation in winter
Generally low humidity
CLIMATE TYPE
TEMPERATURE AND PRECIPITATION
ARCTIC AND SUBARCTIC
• Subarctic; Tundra
• Ice Cap
HIGHLANDS
• Cool to cold short summers
• Extremely cold winters
• Dry climate with some summer and
winter precipitation
• Great variety of conditions based
on elevation, prevailing winds, sunor non-sun-facing slopes, latitude,
valley or non-valley, ruggedness.
TYPES OF RADIATION
• Radiation refers to the emission of energy in the
form of electro-magnetic waves from all bodies
whose temperature is above 0°K.
A. Solar Radiation
• Shortwave radiation whose wavelength ranges from
0.3 – 3 micron meters (3000 – 30,000 A°) (Angstron).
• Half consists of visible light (0.4 – 0.7 micron meters).
• Corresponds to the emission of a black body whose
temperature is 6000°K (solar constant).
• It reaches the outer surface of the atmosphere at a
nearly constant flux of 2 Langley/minute (or 2
calories/min cm2).
Solar Radiation
• It changes its flux and spectral composition while
passing through the atmosphere as a result of
reflection, absorption and scattering.
• Reflection: About ⅓ is reflected back to space as
a result of the atmospheric composition e.g.
water vapour/clouds. It can be as high as 80%
when the sky is completely overcast with clouds.
• Absorption and scattering of solar radiation
cause only about half of the original flux density
to finally reach the ground.
Solar Radiation
• Direct solar radiation is the part that reaches
the ground without being reflected or
scattered.
• Sky radiation: Part of the reflected and
scattered solar radiation that reaches the
earth.
• Global Radiation = Sky Radiation + Direct
Radiation
B. Terrestrial Radiation
• Part of the solar radiation that reaches the
earth surface is radiated (or emitted back) to
space as terrestrial or longwave radiation
(infra red).
• The temperature of the earth surface is about
300°K. Therefore, the terrestrial radiation is of
much lower intensity and greater wavelength
than solar radiation.
• The wavelength of the terrestrial radiation is
therefore long in the range of 3 – 50 micron
meters (longwave radiation).
C. Blackbody Emittance and Spectral
Distribution
• A blackbody is one which absorbs all radiation
reaching it without reflection and emits all
radiation at maximal efficiency. The sun is an
example of a blackbody.
RADIATION LAWS
I. Plank’s Law: There are two principles:
1st Principle: ℮ = hv………………. (1)
Where: ℮ = energy per photon
h = Plank’s constant
v = frequency of radiation
v = c/λ……………………….(2)
Where: c = speed of light
λ = wavelength
Combining (1) and (2) gives
℮ = hc/λ………………………(3)
RADIATION LAWS
2nd Principle:
The intensity distribution of energy emitted by a
blackbody as a function of wavelength and
temperature:
Eλ = 2πhc2/ λ5 [exp (hc/KT)-1]
Where: K = Boltzmann’s constant
T = Absolute Temperature (°K)
Eλ = Spectral emittance of blackbody
RADIATION LAWS
II. Stefan – Boltzmann’s Law:
The total energy emitted by a body integrated over
all wavelengths is proportional to the fourth power
of the absolute temperature:
i.e. Jt = εᵹT4
Where: ε = emissivity coefficient
ᵹ = Stefan-Boltzmann’s constant
ε = 1 for a blackbody
RADIATION LAWS
III. Wien’s Law:
The maximum energy per unit wavelength emitted
λm is given by:
λm = 2897/T…………………(1)
Where T = absolute temperature, K
D. Greenhouse Gases
• There are absorptive gases that occur in the
atmosphere and are responsible for the partial
trapping of emitted longwave from the earth
that causes global warming. The principal
greenhouse gases are: water vapour (H2O),
carbon dioxide (CO2), Ozone (O3), Methane
(CH4) and nitrous oxide (N2O).
Sources of Principal Greenhouse Gases
Gas
Natural Source
Anthropogenic Source
CO2
Terrestrial biosphere,
Oceans
Fossil fuel combustion
(coal, petroleum),
cement production,
landuse change
CH4
Natural wetlands,
Termites
(metabolism), oceans
and freshwater, lakes
Fossil fuels (natural
gas production, coal
mines, petroleum
industry), Enteric
fermentation of
ruminants, Rice
paddies, Biomass
burning, Landfills,
Animal wastes,
Domestic sewage
Gas
Natural Source
N2O
Oceans, Tropical soils, Nitrogen fertilizers,
Temperate soils
Industrial sources,
adipic acid/nylon,
nitric acid, landuse
change (biomass
burning, forest
clearing)
CFCs
Anthropogenic Source
Rigid and flexible
foam, Aerosols
propellants, Teflon
polymers, Industrial
solvents, Refrigeration
coolants
SOIL MANAGEMENT PRACTICES AND
GREENHOUSE GAS EMISSIONS
Agriculture and soil management practices that
contribute to greenhouse gas emissions are:
• Animal production
• Agricultural Residue Burning
• Application of nitrogen mineral fertilizers
• Application of crop residues to soil
• The use of nitrogen fixing crops in soil management
• Production of paddy rice
• Tillage and direct emission from soil
• Land use change
1. Animal Production
• Enteric Fermentation: Methane production
from herbivores is a by-product of enteric
fermentation, a digestive process by which
carbohydrates are broken down by microorganisms into simple molecules for
absorption into the blood stream. Both
ruminants (e.g. cattle, sheep) and nonruminants (e.g. horses and pigs) produce CH4
although ruminants are the largest source.
1. Animal Production
• Manure Management: Methane and nitrous
oxide are produced from the decomposition
of manure under low oxygen or anaerobic
conditions. These conditions occur when large
number of animals are managed in a confined
area and where manure is typically stored in
large piles or disposed off in lagoons.
2. Field Burning of Agricultural Residue
• Burning of crop residues and other agricultural
wastes in the field produces emissions of CH4,
CO, CO2, N2O and Nox. Usually CO2 from
vegetal or biomass burning is noted for
information but is not included in the
inventory total, since it is assumed that a
roughly equivalent amount of CO2 is removed
by regrowth of the next crop.
3. Application of nitrogen mineral
fertilizers
• Addition of mineral fertilizer to soils increases the amount
of nitrogen (N) available for nitrification and de-nitrification
and, hence, the amount of N2O emitted.
• The emission of N2O that results from anthropogenic N
inputs occur through both a direct pathway (i.e. directly
from the soils to which the N is added), and through
indirect pathways (i.e. through volatilization as NH3 and
Nox).
• Among the direct N2O emissions due to N inputs (i.e. in
addition to synthetic fertilizers) are emissions due to animal
manure, use of N-fixing crops, incorporation of crop
residues into soil and N mineralization in organic soils.
4. Paddy Rice Cultivation
• The anaerobic decomposition of organic
material in flooded rice fields produces
methane, which escapes to the atmosphere
by ebullition (building up) through the water,
diffusion across the water/air interface, and
transport through the rice plants.
• N2O emissions from the use of nitrogen-based
fertilizer can also take place in flooded rice
cultivation.
5. Indirect N2O emissions from nitrogen
used in agriculture
• N2O is produced in soils and aquatic systems through
the microbial process of nitrification and
denitrification. A number of agricultural activities
add nitrogen (N) to soils and aquatic systems
increasing the amount of N available for nitrification
and denitrification, and, thus, the amount of N2O
emitted. Some emissions of N2O that result from
anthropogenic N inputs occur through indirect
pathways, including leaching and runoff of applied N
in aquatic systems, and the volatilization of applied N
as ammonia (NH3) and oxides of nitrogen (Nox).
6. Tillage and direct N2O emissions
• Tillage opens up the soil and hastens up
aerobic decomposition of organic matter
resulting in direct emissions of N2O.
7. Land use change
• Land use change generally causes the release
of CO2 that had previously been sequestered
in plant biomass and soil organic matter.
IMPACT OF CLIMATE CHANGE ON
AGRICULTURAL PRODUCTION
1. Carbon Dioxide, Climate and Crop Yields
CO2 enrichment
• An enhanced CO2 concentration in the
atmosphere promotes diffusive transfer and
absorption of CO2 into the chloroplasts and its
conversion to carbohydrates.
• This condition holds depending on whether
we are dealing with C3 or C4 plants.
IMPACT OF CLIMATE CHANGE ON
AGRICULTURAL PRODUCTION
1. Carbon Dioxide, Climate and Crop Yields
CO2 enrichment
• C3 plants use up some of the solar energy they
absorb in photorespiration. This process causes a
fraction of CO2 fixed into carbohydrates to be
reoxidized into CO2, thus releasing the chemical
energy that the plant had originally taken in as solar
radiation. This process causes C3 crops (such as
wheat, rice and soybeans) to exhibit lower rate of net
photosynthesis than C4 crops, such as maize,
sorghum, millet and sugarcane.
IMPACT OF CLIMATE CHANGE ON
AGRICULTURAL PRODUCTION
1. Carbon Dioxide, Climate and Crop Yields
CO2 enrichment
• However, in elevated CO2 levels, rates of photosynthesis of
C3 crops may exceed those of C4 plants due to suppression
of photorespiration. In general, C3 crops are more
responsive to CO2 enrichment than C4 crops.
• In C4 plants, CO2 is first captured in the mesophyll cells as
malic and aspartic acids. These acids release CO2, naturally
raising the CO2 concentration and promoting the activity of
the carboxylase over oxygenase enzymatic reaction. In this
manner, photosynthesis is favoured over photorespiration.
IMPACT OF CLIMATE CHANGE ON
AGRICULTURAL PRODUCTION
1. Carbon Dioxide, Climate and Crop Yields
CO2 enrichment
• Respiration and atmospheric CO2 concentration: An increase in
photosynthesis, growth rate and substrate levels should increase
respiration rate, because higher biomass requires higher energy supply
for maintenance and growth. On the other hand, increased CO2
concentration in the air should increase or promote inward diffusion of
CO2 in the plant, which tends to inhibit the diffusive release of CO2 by the
plant and reduces respiration finally.
• Enhanced photosynthesis in higher atmospheric CO2 levels naturally
promotes biomass accumulation. However, responses to elevated CO2
vary among different crops and even among varieties of the same crop.
The varying responses depend in part on environmental factors (i.e.
water and nutrient availability) and in part on genetics.
IMPACT OF CLIMATE CHANGE ON
AGRICULTURAL PRODUCTION
1. Carbon Dioxide, Climate and Crop Yields
CO2 enrichment
• Among crops, the differences between C3 and C4
photosynthetic pathways appear to contribute
the most to the differences in overall response
of crops to elevated CO2.
1. GREENHOUSE GASES AND THEIR CHANGE IN
QUANTITY SINCE THE PRE-INDUSTRIAL TIMES
Atmospheric Concentration CO2 (ppmv) CH4 (ppmv) N2O (ppmv)
Pre-industrial (1750 – 1800) 280
0.8
0.288
Present day (1990)
353
1.72
0.31
Current rate of change per
year
1.8
(0.5%)
0.015
(0.9%)
0.0008
(0.25%)
Atmospheric lifetime (yr)
50 - 200
10
150
Source: Houghton et al. (1990)
* Houghton J.T., Jenkins, G.J. and Ephraums, J.J. (Eds.) (1990). Climate change.
IPCC Scientific assessment (report prepared for IPCC by Working Group 1).
Cambridge University Press.
2. THE GREENHOUSE EFFECT AND THE
CONCEPT OF CLIMATIC FORCING
The two main factors that control the temperature of the
Earth are:
 The incoming solar radiation, and
 The insulating effect of the gaseous atmosphere and its
clouds.
 Invariably, the energy from the sun is constant, and
 The main climatic changes today are the result of changes
in the composition of the atmosphere.
 Without greenhouse effect, the average temperature of
the earth’s surface would be -18°C.
 The current average global temperature is about 15°C, a
difference of 33°C.
3. THE FLOW OF CARBON DIOXIDE TO AND
FROM THE ATMOSPHERE (CARBON BUDGET)
• Exchanges between the atmosphere and the
biosphere, (i.e. plants and animals that live on land
and in the sea).
o plants consume CO2 in photosynthesis as a source
of carbon to grow and emit O2.
o animals consume O2 to live and grow and emit CO2.
• Other normal sources of CO2:
 eruption of volcanoes
 natural fires
 decay of plant and animal materials
3. THE FLOW OF CARBON DIOXIDE TO AND
FROM THE ATMOSPHERE (CARBON BUDGET)
• Long-term sinks of carbon dioxide.
 fixing of carbon as calcium carbonate in the shells of
marine animals.
 fixing of carbon as accumulation of plant and animal
materials to form peat.
 ocean water itself is an absorber of carbon dioxide.
• The other significant contributor to the increased level of
carbon dioxide in the atmosphere is the burning of fossil
fuel.
 This designates an annual transference of some 5 billion
tones of CO2 sequestered by life on earth hundreds of
millions years ago, which is now stressing the biosphere.
3. THE FLOW OF CARBON DIOXIDE TO AND
FROM THE ATMOSPHERE (CARBON BUDGET)
• Global warming potential
The global warming potential is a calculation of the possible
warming effect on the lower atmosphere of each of the
greenhouse gases relative to CO2.
• Climate sensitivity
This is a measure of the response of the global average
temperature to a change in the carbon dioxide
concentration in the atmosphere.
ANALYSIS OF CLIMATE CHANGE, CLIMATE VARIABILITY
AND FUTURE FOOD SECURITY
1. Analysis of climate change impacts
Analysis of the potential effect of global warming on
future agricultural productivity involves the study of
both biophysical and socioeconomic processes.
The several approaches to this study involves:
• Climate change scenarios
• Using thresholds to define the limits of tolerance of
an agricultural system as it is currently configured to
changes in climatic variability.
• Use of economics in the analysis of potential impacts
of climate change.
ANALYSIS OF CLIMATE CHANGE, CLIMATE VARIABILITY
AND FUTURE FOOD SECURITY
I. Climate change Scenarios
They are used as the first step in an assessment of the impacts
of climate change and are defined as plausible combinations
of climatic conditions that may be used to test possible
impacts and to evaluate responses to them.
Uses
• Determination of how vulnerable agriculture is to climate
change.
• Identification of the thresholds at which impacts become
negative or severe.
• Comparison of relative vulnerability among sectors in the
same region or among similar sectors in different regions.
The Different types of climate change scenarios
•
•
•
•
Scenarios based on arbitrary changes in climate variables.
Analog warming in previous times.
Global circulation models (GCMs)
Regional climate model simulations (Reg CMs)
(a) Arbitrary scenarios
This uses statistical regression and crop growth models. The
rise in temperature and reduction in precipitation are
arbitrary set and fed to crop growth model to predict the
yield. Using different temperatures and amounts of
precipitations, different arbitrary crop yield values are
obtained. Statistical regression is obtained using the arbitrary
crop yields and arbitrary temperatures and precipitations.
The Different types of climate change scenarios
•
•
•
•
Scenarios based on arbitrary changes in climate variables.
Analog warming in previous times.
Global circulation models (GCMs)
Regional climate model simulations (Reg CMs)
(a) Arbitrary scenarios
This uses statistical regression and crop growth models. The
rise in temperature and reduction in precipitation are
arbitrary set and fed to crop growth model to predict the
yield. Using different temperatures and amounts of
precipitations, different arbitrary crop yield values are
obtained. Statistical regression is obtained using the arbitrary
crop yields and arbitrary temperatures and precipitations.
The Different types of climate change scenarios
(b) Historical Analogs
Warm and dry historical periods are constructed. For example
the warmest 5 – year period in the country or the driest 5 – year
period in the country. The historical yields of the specific crops
for the 5 – year periods are collected. Statistical regressions are
employed to establish the relationships.
(c) Global circulation models (GCM – Based Scenarios)
• GCMs estimate how global and regional climates may change
in response to increased concentrations of greenhouse gases.
• Regional and global climate responses are mutually and
physically consistent as heat, moisture and energy processes
are calculated from the same set of equations representing
physical processes.
The Different types of climate change scenarios
(c) Global circulation models (GCM – Based Scenarios)
• A full set of climate variables (including wind, solar radiation,
temperature, precipitation, cloud cover and soil moisture) is
provided by GCM output for use in a wide variety of impact
models.
• GCM scenarios provide climate variables for impact
researchers and resource managers to test responses of
systems to simultaneously altered conditions in different
regions.
• GCM climate change scenarios provide a global framework in
which details regional case studies can be conducted.
2. Predicting the future climate change
• GCMs are also used to predict and simulate
the world’s future climate changes.
• The variables that drive these models include:
 information concerning energy input from
the sun, and
 gaseous composition of the atmosphere.
• Principles in using GCMs
 The world is divided into a grid system with
points separated by several hundred
kilometers horizontally and also several
kilometers vertically above the earth surface.
2. Predicting the future climate change
• Principles in using GCMs
 The world is divided into a grid system with
points separated by several hundred
kilometers horizontally and also several
kilometers vertically above the earth surface.
 calculations are done only at the
intersections of the points using equations
describing the interaction of the parts of the
ocean-atmosphere system and the basic
physical laws (i.e. the conservation of mass,
momentum and energy and the ideal gas law).
3. Fundamental Equations represented in GCMs
• Conservation of momentum
(Newton’s second law of motion)
dv/dt = 2n × V – P –ΔP + g + F
Where:
V = velocity relative to rotating earth
n = Planet’s angular velocity vector
F = force per unit mass
3. Fundamental Equations represented in GCMs
• Conservation of mass (continuity equation)
dρ/dt = –ρΔ.V + C - D
Where:
ρ = atmospheric density
C = rate of creation of (gaseous) atmosphere
D = rate of destruction of atmosphere
3. Fundamental Equations represented in GCMs
• Conservation of energy (first law of
thermodynamics)
dI/dt = –ρ dp + Q
dt
Where:
I = internal energy per unit mass
Q = heating rate per unit mass
3. Fundamental Equations represented in GCMs
• Ideal gas law (equation of state)
P = ρRT
Where:
P = atmospheric pressure
R = universal gas constant
T = absolute temperature
4. Examples of GCMs
• GISS – Goddard Institute for Space Studies
(USA)
• UKMO – United Kingdom, Meteorological
Office
• CCC – Canadian Climate Centre
• GFDL – Geophysical Fluid Dynamics
Laboratory (USA)
• CSIRO – Commonwealth Scientific and
Industrial Research Organization (Australia)
5. Strengths and Weaknesses of GCMs
• Strengths:
They are consistently and internally logical.
They include simultaneous and interacting
processes.
They depict (show) global integration.
They are better adapted to stimulating.
temperature (which is a spatially continuous
variable).
5. Strengths and Weaknesses of GCMs
• Weaknesses
 Incomplete understanding of ocean circulation pattern.
 Lack of knowledge concerning the formation of feedback effects of
clouds (whether positive or negative).
 Simplistically formulated hydrological processes (i.e. ignoring land
surface and vegetation features).
 Spatial resolution is coarse.
 Lack of understanding of cloud processes hinders projections of the
magnitude of climate change.
 The under developed state of ocean models limit the ability of the
present-day models to predict the time rate of change and its
regional patterns.
 At current use of grid spacings, GCMs do not resolve atmospheric
events such as fronts, and severe storms that take place over small
distances.
6. Regional Climate Models and Downscaling
• Regional climate models (Reg CMs) nested
within GCMs simulate climate at finer
resolutions (i.e. up to few kilometers) over
selected regions.
• In Reg CMs the effects of complex topography,
vegetation mixtures, coastlines, and large
lakes that regulate local circulations and
regional distribution of climate variables are
represented in more physically realistic ways.
Examples of Reg CMs
• GENESIS: (Nation Center of Atmospheric
Research (NCAR) (USA).
• Japan Meteorological Agency Limited Area
Model.
• DARLAM of CSIRO.
DOWNSCALING
• Downscaling is a technique used to provide
Regional climate detail for climate change
using GCMs.
• GCMs are used to describe the atmospheric
response to large scale forcings and empirical
techniques are used to account for mesoscale
forcings. Statistical climate inversion is used to
derive relationships between large-scale and
local surface climate variables.
DOWNSCALING
• Examples: Regression formulas are generated
from GCMs output and used to predict regional
distributions of daily climatic variables.
• Empirical relationships are developed between
observed surface weather variables and modelproduced astmospheric and surface weather
predictors. The predictors can include regional
average surface air temperature and
precipitation, mean sea-level (pressure etc).
• Downscaling techniques improve regional climate
projections – this is an advantage.
Weaknesses of Downscaling techniques
• Work less when climate variables are not
spatially well correlated – e.g. summer time
precipitation.
• They suffer from lack of physical explanatory
power, thus lacking the ability to work under
different climate forcings.
7. Weather Generators
• Weather generators are mathematical techniques for
generating synthetic time series of weather. They are
important tools for climate change impact studies.
They are particularly useful in developing scenarios
of changed climate variability.
• The weather generator WGEN developed by
Richardson (1981) has been used as a basis for the
generation of climate change scenarios. This is a
stochastic weather generator which stimulates daily
times series of maximum and minimum
temperatures, incident solar radiation and
precipitation.
7. Weather Generators
• Richardson, C.W. 1981. Stochastic simulation
of daily precipitation, temperature and solar
radiation. Water Resources Research, 17: 182190.
• Richardson, C.W. and D.A. Wright (1984).
WGEN: A model for generating daily weather
variables. US Department of Agricultural
Research Services. ARS Publication 8.
Washington, DC.
IMPACT OF CLIMATE CHANGE ON FOOD SECURITY
• Food security defined: Access by all peoples at all times to
enough food for an active, healthy life (World Bank, 1986).
• National food availability includes:
o Production in the agricultural sector, less the amount
exported, plus the amount of food imported and food aid
received.
• Food availability at household levels includes:
o food that a household raises on its own, the food that, a
family can buy, plus additional food received as welfare or
food assistance and gifts.
• Food availability at individual level may vary within a family or
household according to age, gender, economic status and
cultural systems.
MEASURES OF FOOD SECURITY
Food security can be threatened by:
• Famine (800 million people in 1957 – 1963)
(About 100 million people in 1985 – 1991)
• War (as hunger is often used as a weapon).
• Chronic undernutrition (according to FAO, about 700
million people suffer from chronic undernutrition).
• Child malnutrition due to lack of food quantity,
micronutrient deficiency due to inadequate dietary
quality, e.g. iron, iodine and vitamin A deficiency).
• Illness that deplete the body’s ability to utilize nutrients
such as diarrhea, measles, malaria and intestinal
parasites.
VULNERABILITY TO FAMINE, CLIMATE CHANGE AND FOOD
INSECURITY
• Vulnerability to famine, climate change and food
insecurity is a complex concept that integrates
environmental, social, economic and political
aspects.
• Vulnerability has three components:
 risk of exposure to crises, stress and shocks
 risk of inadequate capacity to cope with crises,
stresses and shocks
 and risk of severe consequences with associated
slow or limited recovery from crises, stresses and
shocks.
VULNERABILITY TO FAMINE, CLIMATE CHANGE AND FOOD
INSECURITY
• Thus, groups most vulnerable to climate change in regard to food
security may be those:
 who are exposed to the risk of climate change impacts on crop
productivity and changes in commodity prices.
 with least capacity to cope with unfavourable changes in
agricultural conditions and to access food, and therefore prone to
suffer the consequences of famine, undernutrition and debility.
• Potential groups likely to be vulnerable to climate change and its
attendant hunger (food insecurity) are:
 rural smallholder farmers
 pastoralists
 wage labourers
 urban poor
 refugees and other destitute groups
VULNERABILITY TO FAMINE, CLIMATE CHANGE AND FOOD
INSECURITY
• Reducing vulnerability to climate change impact on
agricultural and food security requires:
 lessening the risk of climate change on agricultural
productivity and access to food;
 enhancing the capacity of vulnerable groups to adopt
their farming systems or economic livelihoods to changing
agroclimatic and market conditions;
 improving their ability to recover temporary food
shortages e.g. through importation of food and food aids;
 and minimizing the potential disruptions to food
production that may result from either governmental or
donor interventions.
VULNERABILITY TO FAMINE, CLIMATE CHANGE AND FOOD
INSECURITY
• Factors needed to achieve goals of lessening vulnerability
to hunger and promoting sustainable growth in the
agricultural sector with regard to threat posed by climate
changes are:
 combining efforts on a broad multi-disciplinary front in
the fields of agriculture, health and the environment.
 institution of government policy towards poverty
reduction.
 improving access to good education.
 provision of good access roads and other infrastructure.
 improvement in marketing structures and agricultural
storage and processing facilities.
CLIMATE CHANGE AND CLIMATE VARIABILITY
• Climate variables can be time-averaged on a daily,
monthly, yearly or longer basis.
• Climate variables may oscillate or vary about their
mean values.
• Climate change refers to an overall alteration of mean
climate conditions.
• Climate variability refers to fluctuations of the climate
variables about the mean.
• Under enhanced greenhouse effect, changes occur in
both the mean values of climate parameters and the
frequency and severity of extreme (meteorological)
events, e.g. spells of extra high temperature, torrential
storms, or droughts.
CLIMATE CHANGE AND CLIMATE VARIABILITY
• The relationship between changes in mean temperature and
the corresponding changes in the probabilities of extreme
heat spells tends to be non linear. Thus, relatively small
changes in mean temperature can trigger relatively large
increases in the frequency of extreme events. For that matter,
such days with very high temperatures can be deleterious to
crop growth.
• Also, the increase in the probability of drought may be greater
than the relative reduction in overall rainfall amount. This is
so because a reduction of rainfall is generally accompanied by
a rise of potential evapotranspiration, thus raising the
demand for water by plants even while reducing the supply.
The rise in potential evapotranspiration may induce drought
conditions even where precipitation per se increases.
CLIMATE CHANGE AND CLIMATE VARIABILITY
• How does the variability of climate affect crop growth
and how a change in variability alter crop
performance?
• Climate variability effect on crop productivity:
Precipitation, being the key supplier of soil moisture, is
the most important factor determining the productivity
of crops. A change in climate can cause changes in total
seasonal precipitation, its within season pattern and its
between-season variability. For crop productivity, a
change in the pattern of precipitation and its variability,
may be even more important than a change in the
annual total per se. The annual total may be influenced
by a single heavy down-pour of precipitation.
EFFECTS OF WATER STRESS ON CROP GROWTH
AND YIELD
• Under elevated temperature conditions, a greater
evaporative demand is induced. If crops are not
sufficiently watered, they are likely to suffer moisture
stress and eventually growth may be curtailed.
• Water stress in plants is associated with:
 reduced energy potential and activity of cellular water;
 lower cell turgor pressure of plant cells;
 increasing concentration of solutes in plant cells;
 shrinking of cell volume; and
 Diminished hydration of plant tissues.
EFFECTS OF WATER STRESS ON CROP GROWTH
AND YIELD
• As water stress develops, plants tend to lower the
osmotic potential of their cells, a process that helps
them maintain turgor. Osmotic adjustment allows cell
enlargement and growth to continue at water
potentials that would otherwise be inhibitory.
• In the initial stages of drought stress, turgor may be
maintained by osmotic adjustment; if the stress
persists, however, plants lose the capacity to adjust.
EFFECTS ON CROP YIELDS
• Crop yields suffer if dry periods occur during the
critical period of reproduction stage.
• Water stress in transpiring leaves driving
reproductive development may draw water out
of fruits and grains.
• Drought hastens the senescence of older leaves
and induces premature abscission.
• Moisture stress during the flowering, pollination,
and grain-filling stages is specially harmful to
maize, soybean, sorghum and wheat.
ADAPTIVE MEASURES TO OVERCOME ADVERSE EFFECTS OF
CLIMATE CHANGE ON AGRICULTURE
• Introduction of late-maturing or early-maturing varieties or
species as the situation demands;
• Changing cropping sequences;
• Adjusting timing of planting and other filed operations;
• Conserving soil moisture through conservation tillage
methods;
• Improving irrigation efficiency;
• Adoption of agroforestry systems;
• Switching crop varieties;
• Installing new irrigation systems;
• Shifts in regional production centres;
• Development of heat/drought-tolerant crop varieties;
ADAPTIVE MEASURES TO OVERCOME ADVERSE EFFECTS OF
CLIMATE CHANGE ON AGRICULTURE
II. Adaptation defined: Any action that seeks to reduce the negative
effects, or to capitalize the positive effects of climate change.
III. Adaptive actions may be either anticipatory or reactive in
nature.
• Anticipatory Actions
Physical or operational aspects of systems and to be made in
advance of the impending climate change, e.g. development of
heat and drought-tolerant varieties, before the appearance of the
impacts.
• Reactive Adaptations
When and if actual impacts, either positive or negative occur, the
decision will be to undertake reactive adaptations.
ADAPTIVE MEASURES TO OVERCOME ADVERSE EFFECTS OF
CLIMATE CHANGE ON AGRICULTURE
For example, release of reservoir water meant for domestic use,
during drought periods, for irrigation.
• Using maize crop for fodder instead of awaiting ripening during
drought periods
IV. Farm-level adaptations versus economic adjustments
• Farm-level adaptations can be tested by crop models and
include:
 shifts in planting dates;
 use of climatically adapted crop varieties;
 changes in amount and timing of irrigation;
Changes in fertilizer application.
ADAPTIVE MEASURES TO OVERCOME ADVERSE EFFECTS OF
CLIMATE CHANGE ON AGRICULTURE
• Economic adjustments may be simulated by
comprehensive economic models and result in
national as well as regional production changes and
price responses which include:
 increased investment in agricultural infrastructure;
 reallocation of existing resources (e.g. land and
water) according to economic returns;
Reclamation of additional arable land; and
 use of additional inputs as a response to higher
commodity prices.
ADAPTIVE MEASURES TO OVERCOME ADVERSE EFFECTS OF
CLIMATE CHANGE ON AGRICULTURE
V. The concept of resilience and robustness pertaining to
adaptation
• Resilience is the ability of a system to return to a predisturbance
state without incurring any lasting, fundamental change.
 Resilient resource systems may fail temporarily when
perturbed, but recover after the perturbation ceases.
• Robustness is the ability of a system to continue to function in a
wide range of changed conditions.
 Robust systems maintain their properties and outputs even
under unusual stress, by virtue of strength and control rather
than flexibility.
 system robustness may be increased with increased
investment, structural strength, and operational control.
ADAPTIVE MEASURES TO OVERCOME ADVERSE EFFECTS OF
CLIMATE CHANGE ON AGRICULTURE
VI. Other important aspects of adaptation to climate change in
agriculture and other sectors
• Adaptation to climate change must enhance characteristics that
offer flexibility. Flexibility issues are particularly important in
regard to the development of water resources for agriculture.
• It may be wise to wait until potential climate change is
actualized before certain projects are implemented.
• In agricultural planning, the appropriate response to the climate
change issue, given the present state of knowledge, is further
study and monitoring rather than major anticipatory actions.
• If actions are to be taken at all, they should be those that will
bring improvements to contemporary conditions whether or not
climate change indeed occur.
ADAPTIVE MEASURES TO OVERCOME ADVERSE EFFECTS OF
CLIMATE CHANGE ON AGRICULTURE
• In regard to adaptive responses of agriculture to
climate change, the following questions should be
considered:
 what are the institutional and organizational
capabilities for adaptation to climate change?
 what secondary problems might be caused by
adaptation to climate change?
 what is the range of choices for adapting to climate
change?
 how do economics and finance, environmental
concerns, international relations affect the range of
choice?
ADAPTIVE MEASURES TO OVERCOME ADVERSE EFFECTS OF
CLIMATE CHANGE ON AGRICULTURE
Limits to Adaptation
• The degree of application and adaptation and the
efficacy of various adaptive practices are uncertain:
 there may be social or economic reasons why
farmers are reluctant to implement certain yieldenhancing measures. For example, increased fertilizer
application or other improved practices may be too
costly or otherwise not compatible with indigenous
patterns of production and assumption.
 furthermore, such measures may not necessarily
lead to sustainable production e.g. increased
salinization with irrigation.
ADAPTIVE MEASURES TO OVERCOME ADVERSE EFFECTS OF
CLIMATE CHANGE ON AGRICULTURE
Limits to Adaptation
• Some adaptive measures may have detrimental impacts.
For example, where shifts are made from grain production,
farmers may find themselves more exposed to marketing
and credit problems brought on by higher capital and
operating costs.
• Changes in planting schedules or in crop varieties as an
effort to minimize impacts on agricultural incomes may not
necessarily ensure equal levels of nutritional quality or food
production, nor equal profits for farmers.
• Increased demand for water by competing sectors may
limit the viability of irrigation as a sustainable adaptation to
climate change.
IMPACT OF CLIMATE CHANGE ON SOIL
AND WATER RESOURCES
• The quantitative evaluation of climate change impact on soil
conditions is difficult due to:
 uncertainties in the forecasts
 complex interactive influences of hydrological regime,
vegetation and landuse
• Soil properties and thermal regimes.
 Higher temperatures will lead to a wide range of soil as
well as plant responses to global climate change.
 Many effects of climate change on soils will take decades
or centuries to be manifested; for instance changes in
colours, and diagnostic horizons may take more than 100
years to occur.
IMPACT OF CLIMATE CHANGE ON SOIL
AND WATER RESOURCES
• Soil texture: soil texture changes slowly with time because
physical and chemical weathering are slow processes. The
characteristic response time for soil texture is on the order
of a Millennium. Maximum clay illuviation (migration within
the soil profile) occurs in warm, wet climate regimes with
acid forest litter. As climatic zones shift, these textural
processes will slowly change in response.
• Soil structure is even more complex than soil texture
because it is influenced by the intensity of precipitation,
amount of surface runoff and infiltration, root distribution,
earthworms, and other soil fauna, and compaction of
agricultural machinery.
CLIMATE CHANGE AND THERMAL
REGIME OF SOIL
• Climate change from enhanced greenhouse effect
can influence the thermal regime of the soil by
increasing the solar energy input to the soil surface.
This input of energy will tend to raise:
Soil temperature
Heat conduction through the soil profile
Convective transfer through the movement of gas
and water in the soil
Transformation of sensible heat to latent heat in
the process of evaporation
CLIMATE CHANGE AND THERMAL
REGIME OF SOIL
• The process by which nutrient elements become available
to plant are affected by climate variables. Nutrient
dynamics typically take place in the topsoil (within a few
centimeters from the surface, where microbiological
activity is concentrated).
• Warmer temperatures tend to hasten the chemical
processes that affect soil fertility; for example,
decomposition of organic matter, which releases nutrients
in the short run but may reduce soil fertility in the long run
due to decomposition losses.
• Both organic matter and carbon:nitrogen ratio tend to
diminish in warmer conditions due to increased rate of
decomposition by microbial action.
CLIMATE CHANGE AND THERMAL
REGIME OF SOIL
• Clay content tends to increase with increased soil
temperature due to accelerated weathering of primary
minerals.
• Nitrification is accelerated in warm soils.
• Denitrification also increases with increased soil
temperatures.
• The rate of phosphate uptake is enhanced as soil
temperatures rise.
• However, high soil temperatures may have a
depressing effect on symbiotic nitrogen-fixing bacteria
that attach themselves to the roots of legumes.
CLIMATE CHANGE AND THERMAL
REGIME OF SOIL
• Even though nutrient availability increases with increased
temperature, it is difficult to make accurate predictions as
to how crops may respond since the rate at which nutrients
are lost to the atmosphere and groundwater may also
increase.
• Generally higher soil temperatures accelerate chemical
reaction rates and diffusion-controlled reactions:
 The solubility of potassium and sodium salt rises with
temperature.
 Calcium salts diminish in solubility as temperature rises.
 Carbon dioxide, nitrogen and oxygen gases exhibit
reduced solubility in warmer conditions.
CLIMATE CHANGE AND THERMAL
REGIME OF SOIL
• Mineralization is increased and
availability of phosphorus and potassium
is improved with higher temperatures,
while soil colloid formation is speeded
up.
• Higher temperatures contribute to
increased evaporation and thus drier soil
moisture regime.
HYDROLOGICAL EFFECTS DUE TO CLIMATE
CHANGE ON SOIL NUTRIENTS
Climate change may either decrease or increase the
amount of precipitation.
• As the amount of precipitation increases:
 clay content tends to increase
 soil pH tends to decrease
 calcium carbonate, where available, also tends to
decrease
• The process of nitrification is inhibited in wet soils.
• The process of denitrification is enhanced where
high precipitation raises the water table in poorly
drained soils.
HYDROLOGICAL EFFECTS DUE TO CLIMATE
CHANGE ON SOIL NUTRIENTS
• In well drained soils, increased
precipitation promotes leaching of
nitrates.
• Soil water movement corresponds to
increased soil temperature, as water
tends to move from a region of higher
temperature to a region of lower
temperature.
GLOBAL CARBON CYCLE AND CLIMATE CHANGE
• The soils are a major reservoir of carbon holding
about twice as much carbon as the atmosphere (1.5
× 1012 t C in soil as against 7.5 × 1011 t C in the
atmosphere).
• Additional 7.5 × 1012 t of carbon is held in inorganic
forms contained in the deeper layers below one
meter depth, as calcium carbonate (CaCO3).
• The different soils store varying amounts of organic
carbon near the surface, depending on climate
regimes.
• A significant portion of soil carbon is readily released
to the atmosphere as CO2 following decomposition
processes (labile C).
GLOBAL CARBON CYCLE AND CLIMATE CHANGE
• The amount of labile C depends on the annual
contribution of plant residues and the rate at
which the residues are oxidized by microbes. This
rate of oxidation is temperature dependent.
• The estimated mean residence time of soil
organic matter in the tropical savannas is about
10 years.
• Soil respiration (annual carbon flux) from the soil
to the atmosphere is estimated to total about 6.8
× 1010 t C yr-1 about 14 times the annual release
from the burning of fossil fuels (about 5 × 109 t C
yr-1).
GLOBAL CARBON CYCLE AND CLIMATE CHANGE
• The two main sources of soil carbon dioxide are:
 Decomposition of organic matter by microbes
and
 Respiration of live roots and mycorrhizal fungi.
• The tendency of a rising temperature to hasten
decomposition may also be offset in part by the
negative impact of increased C:N ratios on
decomposition as well as the negative impact of
drought on decomposition, where droughts
become more frequent and prolonged due to
global warming.
GLOBAL CARBON CYCLE AND CLIMATE CHANGE
• It is estimated that if world temperatures rise at a
rate of 0.03°C yr-1, the additional release of CO2
from soil organic matter will be 6.1 × 1010 t C over
the period of the next 60 years. This would be
equivalent to about 20% of the projected CO2 flux
from fossil fuel over the same period.
• It is estimated that a 3°C warming would cause an
estimated 11% decrease in soil organic matter in
the upper 30cm of average soils in the temperate
zone. This could contribute to an estimated 8%
increase in atmospheric CO2 (compared to the
1990 level over a 50 year period).
GLOBAL CARBON CYCLE AND CLIMATE CHANGE
• Accelerating soil organic matter decomposition will
boost the production of organic acids, which may
intensify the weathering of rocks.
• Depletion of soil organic matter may result in the
release of heavy metals (e.g. lead, mercury and
cadmium) from soils exposed to atmospheric
pollution and acid rain.
• Other agricultural processes that affect global
carbon balance include:
 accelerated soil erosion;
 biomass burning and
 depletion of soil fertility
GLOBAL CARBON CYCLE AND CLIMATE CHANGE
• Soil erosion due to water may cause
about 1Gt of carbon to be lost to the
atmosphere each year.
• Biomass burning in shifting cultivation is
estimated to release 6.25 × 1010 t C yr-1.
• The loss due to natural fires in tropical
savannas may be as much as 1.88 × 108 t
C yr-1.
AGRICULTURAL PRACTICES AND SOIL
DEGRADATION
• The practices include:
 Mechanized deforestation;
 Conventional tillage farming;
 Continuous cropping on marginal lands;
 Low-input and resource-based shifting cultivation;
 Subsistence farming that leads to soil fertility depletion;
 Over-stocking and over-grazing of livestock
• These degradative agricultural practices lead to depletion
or loss of soil organic carbon.
• Tropical ecosystems, especially in dry regions, are more
prone to degradation than temperate ones.
SOIL ORGANIC CARBON SEQUESTRATION
• Increasing the amount of carbon held in organic
matter in agricultural soils has been proposed as a
means of mitigating the enhanced greenhouse effect
and global warming.
• Model of soil carbon and nitrogen dynamics with
crop growth shows simulated equilibrium. Soil
carbon tends to rise with:
 Lower temperatures
 Increasing clay content
 Enhanced nitrogen fertilization
 Greater manure application and
 Crops with higher residues
SOIL ORGANIC CARBON SEQUESTRATION
• Reduced tillage, such as zero tillage, or
minimum tillage practices tended to increase
soil organic carbon, but when simulated
precipitation was low reduced tillage had little
effect on soil carbon in clayey soils and in soils
with low initial carbon content.
• However the model indicated further that
reduced tillage reduced
 Wind and water erosion
 Energy consumption of cropping and
 Leaching of nitrates
SOIL ORGANIC CARBON SEQUESTRATION
• For carbon sequestration to be significant:
 Substantial additions of organic matter to
the soil are needed in the form of manure
or crop residues;
 Reduced tillage is essential; and
 Improved efficiency of nitrogen fertilization
is indeed useful.
IMPACT OF CLIMATE CHANGE ON WATER
RESOURCES
• When climate change occurs, it is likely to change the
hydrological regimes of entire regions and it must be factored
into water resource planning and policies for the future.
• Crops growing in the field are subject to evaporative demand
imposed by the climatic variables of the environment.
• The parameters that affect evaporative demand of the crop
are:
Temperature
Net radiation
Atmospheric humidity, and
Degree of windiness
IMPACT OF CLIMATE CHANGE ON WATER
RESOURCES
• These climatic variables are influenced by the global
climate change, which will be manifested in changes in the
water regimes of crops and the global hydrological cycle.
• Potential evapotranspiration tends to rise mostly where the
temperature is already high. Consequently, climate change
that results in temperature rise, will create drier conditions
in the tropics.
• Therefore the demand for and the supply of water for
irrigation will be affected by changing hydrological regimes
in the tropical environment when climate change leads to
rise in the temperature and drier climatic regimes.
IMPACT OF CLIMATE CHANGE ON WATER
RESOURCES
• When climate change results in reduced precipitation, it will
have negative impact on all other sources of fresh water such as:
 fresh water lakes
 man-made dams
 groundwater aquifers
 streams and rivers
• The future availability of water resources for agriculture will
depend on:
 changes in precipitation
potential and actual evapotranspiration
runoff at the watershed scale, and
 runoff into rivers, lakes, dams etc.
IMPACT OF CLIMATE CHANGE ON WATER
RESOURCES
• Changes in hydrological regimes due to climate
change will affect the entire management of
water resources, which include:
• reservoir operation
• hydropower production
• Urban water use
• flood control
•Environmental protection and
• irrigation systems
CHANGES IN SOIL MOISTURE AS A RESULT
OF GLOBAL CLIMATE CHANGE
• Changes in soil moisture arises from changes in radiation and
temperature.
• Precipitation is responsible for moisture storage in the upper
layers of the soil.
• Evaporation and runoff deprive the soil of any appreciable soil moisture storage.
• The mechanisms responsible for summer drying of soil
moisture in the tropics are:
 intense evaporation due to summer heat;
 lesser precipitation in the summer;
 reduced cloud cover in the summer leading to more
intense solar energy reaching the soil surface.
CHANGES IN SOIL MOISTURE AS A RESULT OF GLOBAL
CLIMATE CHANGE
• Major emphasis is placed on elevated temperature which is
the most important manifestation of the enhanced
greenhouse effect in the tropics.
• Analysis of soil moisture using GCMs indicates that in most
places summer-time drying of soil moisture is likely to be
most pronounced.
• Increased frequency of drought due to climate change will
precipitate drier soil conditions due to the greater
atmospheric demand for water (i.e. the potential evaporation)
relative to the atmospheric supply of water (i.e. precipitation)
in the tropical environment.
• Dry conditions during the growing period will lower soil
moisture and hence, lower crop productivity because of the
greater likelihood of crop water stress.
CHANGES IN SOIL MOISTURE AS A RESULT OF GLOBAL
CLIMATE CHANGE
• There are some biological factors that would tend to reduce
but not eliminate the negative effects of summer drying on
crop yields. These biological factors include:
 shortening of crop growing periods by faster physiological
development caused by higher temperature;
 shortened growing period implies that less moisture will
be removed from the soil, leading to opportunity of soil
moisture recharge with positive prospects, for the
following growing season;
 the limited crop growth caused by shortened duration of
development will result in decrease in biomass and hence
transpiration rates, leading to increases in residual
moisture after the crop growing period.
WATER RESOURCES AND IRRIGATION DUE TO
GLOBAL CLIMATE CHANGE
• Irrigation is the artificial enhancement of soil
moisture aimed at promoting crop productivity.
• In arid regions, irrigation generally provides most
of the water required for crop growth.
• In more humid regions, supplemental irrigation is
provided periodically to prevent yield losses
caused by seasonal moisture stress.
• About 17% of the world’s cropland is under
irrigation.
WATER RESOURCES AND IRRIGATION DUE TO
GLOBAL CLIMATE CHANGE
• Water for irrigation is taken from:
 surface water resources (lakes, streams and rivers)
and
 ground water (acquifers)
• An important task is to make projections for
irrigation due to global warming. Such projections
can contribute to assessments of future water
requirements for agriculture, since the future welfare
of farmers and rural communities that depend on
irrigation may be critically affected by climate
change.
IRRIGATION REQUIREMENTS VERSUS
GLOBAL WARMING
• Irrigation requirement is the amount of water
needed to irrigate a crop, and it depends
principally on crop evapotranspiration.
• Rising air temperatures generally intensify
vapour pressure deficit and the overall effect
is to increase crop evapotranspiration.
• It is estimated that a 1°C rise in air
temperature would cause between 4 and 8%
increase in evapotranspiration.
FARMER ADAPTATION TO PROJECTED CLIMATIC
CONDITIONS AND FUTURE IRRIGATION REQUIREMENTS
• Switching to longer season crop varieties to
counteract the compression of crop
development and to take advantage of a
longer potential growing season.
• The use of extended –season crop cultivars
will tend to increase seasonal irrigation
requirements.
• The adaption of such cultivars by farmers
depends on:
FARMER ADAPTATION TO PROJECTED CLIMATIC
CONDITIONS AND FUTURE IRRIGATION REQUIREMENTS
 future economics which will be governed by the cost of
applying extra irrigation water and relative changes in yields
(High temperatures will likely depress yields if irrigated
crops, relative to irrigated yields under current temperature
regimes).
 increased length of the total potential growing season and
compressed lengths of specific lifecycles for annual crops
may encourage farmers to grow two or more crops per year
in regions with sufficient water supplies.
 such increases in cropping intensity would almost certainly
result in greater irrigation requirements. Improving the
efficiency of water use will aid the farmer in adapting to
such greater demands.
WATER RESOURCES FOR AGRICULTURE IN RESPONSE
TO THE GLOBAL GREENHOUSE EFFECT
• The hydrological changes resulting from the global
greenhouse effect will influence the supply of water
for agriculture and the other demands for water.
• Farmers practicing irrigation should be less
vulnerable to climate change than dryland farmers,
provided continuing and adequate supply of water
for irrigation is assured.
• However water resources may be limited in terms of
supply due to:
 demand requirements for hydroelectricity
 groundwater withdrawal, and
 climate variability
SOCIAL AND ECONOMIC FACTORS UNDER CHANGING CLIMATE
CONDITIONS IN RELATION TO IRRIGATED AGRICULTURE
• Many social and economic factors must enter into
comprehensive assessment of future regional conditions for
irrigated agriculture under changing climate conditions. These
include:
 farmland values;
 crop prices;
 cost of irrigation (including pumping energy costs);
 cost of production in addition to irrigation;
 government subsidy programs, and
 economic situation of both prosperous and marginal farmers.
• If farmers’ deficit are severe relative to capital investments and
running costs long-term drought can lead to widespread
bankruptcy.
CLIMATE CHANGE AND SEA LEVEL RISE
• Greenhouse warming in global scale would raise sea
level between 20 and 90 cm by 2100, according to
IPCC (1996).
• Sea level is rising due to geologic processes and
anthropogenic manipulation.
• The enhanced greenhouse effect represents an
increase if 2 to 5 times over present rates.
• Mechanisms contributing to sea level rise are:
 thermal expansion of sea water
 melting of mountain glaciers;
 melting of polar ice sheets.
CLIMATE CHANGE AND SEA LEVEL RISE
• Potential impacts of accelerated sea
level rise are:
Inundation of low-lying coastal
areas and estuaries
Retreat of shorelines
Changes and salinization of coastal
water tables (acquifers).
Increased in tidal waves
ECONOMICS AND POLICY ON CLIMATE
CHANGE ADAPTATIONS
A. Economics in the study of climate change impacts on
agriculture
• Biophysical studies on climate change impacts alone
on agriculture are not adequate because:
they do not give data on supply and demand and
their likely effects on prices of agricultural
commodities.
analyses that bring about economic adjustments,
such as when yields decline, prices tend to rise, and
the farmers response to alter production practices
and types of output produced, are not provided.
ECONOMICS AND POLICY ON CLIMATE
CHANGE ADAPTATIONS
A.
•
Economics in the study of climate change impacts on agriculture
 also the decision-making process depends on choices, and economic wellbeing of both producers and consumers should be taken into account in
economic studies.
 further more, economic assessments may provide information on gains and
losses across space and time, as well as on possible benefits and costs to
the society with regards to the role of the climate change policies
developed.
In economic studies of climate change impacts, the following factors are
paramount for consideration as regards farmer and producer adjustments
are concerned.
 selection of crops to be produced;
 input requirements for production;
 alternative technologies available;
 changes in timing of planting; and
 shifts in locations of production.
ECONOMICS AND POLICY ON CLIMATE CHANGE ADAPTATIONS
A.
•
•
•
•
Economics in the study of climate change impacts on agriculture
Adjustments in consumption of agricultural goods can be effected
through:
changing the amount and type of commodities bought
Economic studies should also include indicators of how market
adjustments such as changes in input and output prices may affect the
real net incomes and living standards of producers and consumers,
either domestic or international.
Analyses of the economic consequences of environmental change for
agriculture are necessary if environmental change affects outputs
significantly. This environmental change may also affect price and
quality, which in turn, may lead to further market-induced output
changes.
Moreover, even if prices remain constant while environmental change
does occur, accurate indications of output changes are needed in cases
where individuals can alter production practices and the types of
outputs produced.
ECONOMIC ASSESSMENT OF CONSEQUENCES
OF CLIMATE CHANGE
• Complete assessment of economic consequence of
climate change requires three tasks:
 to measure the differential changes across space
and time that climate changes may cause in the
production and consumption opportunities – such
as crop yields, demand for irrigation water and
water supplies
 to determine the probable responses of input and
output market prices to these changes, and
ECONOMIC ASSESSMENT OF CONSEQUENCES
OF CLIMATE CHANGE
 to determine the probable responses of input and
output market prices to these changes, and
 to identify what adaptations (e.g. the input and
output changes) can be made by affected producers,
consumers and resource owners in order to minimize
their losses or maximize their potential gains from
opportunities and in prices. (For example, farmers
may substitute inputs and change crops produced
while consumers may change the commodities
purchased in response to price signals).
SOME EXPECTED RESULTS OF ENVIRONMENTAL
STRESSES ON AGRICULTURE
• Intensifying stresses increases economic losses.
• Some growers may gain from yield losses because
of environmental stress, due to price increases,
up to a certain point.
• Consumer losses are a substantial portion of the
total loss from environmental stress.
• Economic losses in terms of percentage change
may be smaller than the underlying biophysical
yield changes whenever producers and
consumers can adjust their activities.
SOME EXPECTED RESULTS OF ENVIRONMENTAL
STRESSES ON AGRICULTURE
• Environmental stresses affect both productivity
and demand for inputs, and may have differential
effects in the comparative advantage of regions
or countries.
• Trade flows may be altered, with the result that
some economic sectors may gain, while others
lose.
CHALLENGES IN THE ECONOMIC ASSESSMENT OF
CLIMATE CHANGE IMPACTS ON AGRICULTURE
• Economic assessment does not include
projections of future trends in technology,
demand and population with regard to climate
change impacts on agriculture.
• Economic studies normally do not consider
the potential for changes in the variability of
climate and water supplies.
• Representing the different types of economic
processes, markets and institutions across
countries in a uniform manner is a challenge.
CHALLENGES IN THE ECONOMIC ASSESSMENT OF
CLIMATE CHANGE IMPACTS ON AGRICULTURE
• Individual region or countries may have
different characteristics, and these need to be
represented adequately in terms of common
economic relationship.
• There is a paucity of biophysical and economic
data across different climatic and geographical
domains.
POLICY OPTIONS ON ADAPTATIONS TO
CLIMATE CHANGE
The most promising policy options for agricultural
adaptation are ones for which benefits are realized
even if no climate change takes place. Such policy
options include:
1. Policy for breeding new crop varieties and species
• Breeding objectives should include:
heat-tolerant and low-water use crops
salt-tolerant crops should be introduced in
regions vulnerable to salinization that might be
caused by high water table or sea-level rise
POLICY OPTIONS ON ADAPTATIONS TO
CLIMATE CHANGE
2. There should be a policy to maintain seed banks i.e.
collections of seeds around the world
• Maintenance of these genetic resources will allow:
for future screening for sources of resistance to
diseases and insects that might arise due to climate
change;
 as well as tolerances to heat and water stress and
better compatibility with new agricultural
technologies needed to arrest the constraints to
climate change.
POLICY OPTIONS ON ADAPTATIONS TO
CLIMATE CHANGE
3. Policy to liberalize trade
• Barriers to international trade should be removed to
help the national or regional food system to adjust to
climate changes more efficiently and rapidly.
4. Policy to make commodity support programs to
farmers flexible
• Commodity support programs should encourage
farmers in changing cropping systems. These support
programs will stabilize food supplies and maintain
farm income in the face of future climate change
POLICY OPTIONS ON ADAPTATIONS TO
CLIMATE CHANGE
5. Policy to introduce national or regional agricultural
drought management
• Drought management can be improved by:
 providing information about climatic conditions and
patterns;
 provision of sound preparatory practices and options for
the eventuality of drought;
 provision of appropriate and flexible insurance programs
for farmers; and
 instituting farm disaster relief and other government
subsidies, which may encourage the continuance and
expansion of farming.
POLICY OPTIONS ON ADAPTATIONS TO
CLIMATE CHANGE
6. Policy to promote national or regional efficiency of irrigation and
water use
• Wasteful surface irrigation systems may be converted to more
efficient sprinkle, drip and micro-spray techniques.
• Drainage water and wastewater may be treated and reused for
irrigation.
• Evaporation losses can be reduced by encouraging use of
nighttime irrigation.
• Seepage losses can be reduced by encouraging lining of canals,
use of closed conduits.
• Delivery of water must be measured in quantities and charging of
water must be in proportion to the volume used.
•
Water conservation should be promoted by means of public
education and consciousness raising.
POLICY OPTIONS ON ADAPTATIONS TO
CLIMATE CHANGE
7. National and regional policy in dissemination of conservation
management practices
• Extension to farmers the following conservation management
practices should be encouraged.
 conservation tillage practice;
 furrow diking
Terracing;
 contouring
 Planting windbreaks to prevent fields from wind and water
erosion; and
 practices that retain soil moisture, reduce evaporation and
increases infiltration.
POLICY OPTIONS ON ADAPTATIONS TO
CLIMATE CHANGE
8. Policy to invest in agricultural research and infrastructure
• Research that can identify the specific ways that farmers can
adapt to present variations in climate through the use of:
 more fertilizer
 appropriate mechanization; and
 more labour in agriculture
• Success in adapting to possible climate change will depend on:
 what changes will occur; and
 prudent investments on agricultural systems that bring
about flexibility in preparing for climate change, while
improving the efficiency and sustainability of food
production.
INTERNATIONAL TRADE AND CARBON TRADE AND
THEIR IMPLICATIONS TO DEVELOPING ECONOMIES
1. INTRODUCTION
Carbon trade deals with issues that relocate
carbon-intensive industries to countries
without climate commitment. The resultant
impact of this carbon trade is carbon leakage
between countries with climate regulations
those with lax climate regulations.
INTERNATIONAL TRADE AND CARBON TRADE AND
THEIR IMPLICATIONS TO DEVELOPING ECONOMIES
1.1 Out-sourcing CO2 emissions through
importation of products manufactured in
other countries
•
•
•
Some developed countries try to reduce their CO2
emissions by shifting production and importing
products from less developed economies.
Relocation of production to less developed economies
which use inefficient carbon-intensive industries may
end up in higher global emissions of CO2 as an overall
effect.
A typical example is carbon trade associated with
trade between United States and China.
INTERNATIONAL TRADE AND CARBON TRADE AND
THEIR IMPLICATIONS TO DEVELOPING ECONOMIES
• The United States has managed to
reduce a significant amount of her CO2
emissions through her trade with China.
• The overall effect is that CO2 emissions
are higher because some of the more
efficient systems of production in the
United States are being substituted by
less efficient processes in China.
CARBON ACCOUNTING SYSTEM AND ITS
IMPLICATIONS
• The carbon accounting system pertains to the
nation or state.
• It raises issues regarding the responsibilities of
producer or consumer countries to reduce
their emissions of GHGs.
• It underlines the need for a comprehensive
global regime to tackle climate change and
avoid leakage of carbon emissions from
countries with stringent climate policies to
those without.
1.2.1 The policies if the issue of
carbon accounting system
• Some of the developed economies are dealing
in carbon leakage through international trade
so as to be able to produce most of their
energy-intensive products like cement and
steel domestically.
• Some developed countries are ‘carbon
laundering’ their economies by out-sourcing
environmentally polluting industries to
developing countries.
1.2.2 What needs to be done in
respect of carbon accounting system
• Developed countries must take appropriate
steps to tackle climate change issues to address
their responsibilities with regard to their historic
and current emissions, taking into account the
embodied carbon in their imports.
• Exporting (developing) countries need to
redefine their emission reduction
responsibilities, since their emissions are
directly related to consumption in the
developed countries.
1.2.2 What needs to be done in
respect of carbon accounting system
• The developing economies and the emerging
economies must take measures to improve the
energy efficiency of their industries. This calls
for transfer of more efficient technologies from
the developed countries to the developing
countries where the developed countries are
sourcing large amounts of their consumer
goods from them.
1.2.3 The Economic consequences of
carbon leakage
• Relocating of industries to developing
countries could lead to loss of jobs in
the developed countries.
• Producing goods in developing
countries which have laxitude in
climate standards, can result in carbon
leakage are likely to end up in the
atmosphere.
1.2.4 Measures that may be taken against
countries without much concern over carbon
emissions in terms of trade
• The importing countries which are carbon
emission conscious may decide to increase
border tax towards imports from countries taking
a lax approach to climate change mitigation.
• Climate change bills that would require exporters
of energy intensive good to buy greenhouse gas
“emissions allowances” could be a defensive
action targeted against countries without
stringent climate regulations in place
1.2.5 Contribution of transport sector
through trade to CO2 emissions
• The transport sector has been singled out as
the one where emissions are rising the
quickest and efficiency gains are quickly
outpace by the rise in volume of emissions.
• Therefore, apart from carbon leakage through
international trade, more attention must be
focused in the emissions related to the actual
transport of goods.
• The transparent sector for international trade
is chiefly through:
1.2.5 Contribution of transport sector
through trade to CO2 emissions
 The marine transport sector, which lacks behind other
transport sectors in terms of fuel efficiency and other
standard.
 The international shipping industry largely uses bunker
fuel, which is the waste of production of distillate oil and it
is of poor quality compared to diesel fuel.
 Air Freight: Certain developing countries in Africa air
freight fresh produce to the markets in developed countries
in winter. These developing countries claim that their
overall emissions are much lower than those of importing
countries. These developing countries are already
experiencing the impacts of climate change and have
limited capacity to adapt.
1.2.5 Contribution of transport sector
through trade to CO2 emissions
 Moreover, the aviation sector contributes
around two percent of global carbon dioxide
emissions. When indirect effects from other
pollutants as well as cloud formation are
added, aviation contributes up to nine percent
of radiative forcing or global warming effect.
Emission from aviation have doubled since
1990 and are projected to further grow by 3.5
percent annually.
GENERAL REMARKS ON INTERNATIONAL
TRADE AND CARBON TRADE
• In this age of globalization, there are linkages between trade
and CO2 emissions.
• International trade includes transportation of goods, services,
capital as well as CO2 emissions.
• More work is needed to shed light on issues related to
international trade and climate change.
• More insight is needed on climate change and trade, from
carbon accounting perspective so as to minimize climatic
change impact due to trade.
• A road-map on a treaty to tackle climate change and CO2
emissions due to international trade should be created.
INTEGRATED ASSESSMENT OF THE IMPACTS OF
CLIMATE CHANGE
1. What is integrated assessment of climate
change impacts?
• Most studies of the impact of climate change
look at a certain system in a certain place in
isolation from other systems and other
places. An approach that tries to include the
interactions between the diversity of impacts
of climate change is known as integrated
assessment (IA)
INTEGRATED ASSESSMENT OF THE IMPACTS OF
CLIMATE CHANGE
• For example
 A study of the impact of climate change on
agriculture, keeping the water usage of other
sectors, such as nature, industry and
households constant, may overestimate the
supply of irrigation water for agriculture.
 in integrated impact study, analysis of the
key interactions within and between sectors
is necessary.
INTEGRATED ASSESSMENT OF THE IMPACTS OF
CLIMATE CHANGE
2. Aims of integrated impact study
• To generate a comprehensive assessment of
the totality of impacts, which is greater than
the sum of the separate sectoral impacts.
• To enable researchers to place climate
change impacts in a broader context such as
natural resource management, sustainability
of ecosystems, or economic development.
INTEGRATED ASSESSMENT OF THE IMPACTS OF
CLIMATE CHANGE
3. Integrated assessment is more ambitious than
separate sectoral studies and it is more difficult to
achieve because:
• additional demands are placed on component
studies;
• there is insufficient knowledge of interactions;
• integrated assessment is multi-disciplinary as well
as inter-disciplinary; and
• integrated assessment almost requires co-operation
and often between types of people which might not
be used to cooperating with one another.
INTEGRATED ASSESSMENT OF THE IMPACTS OF
CLIMATE CHANGE
4. Practice in integrated assessment
• Many researchers practice forms of integrated assessment of
climate change using various modelling and non-modelling
approaches.
• Some researchers use pragmatic approaches based on
common sense.
• Linkages between climate sensitive issues (e.g. water
management, agriculture, forestry, fishery and wildlife,
infrastructure planning, and economic development) are
complex, so there is a need for multi-disciplinary collaboration
in a holistic and pragmatic manner that focuses on issues, not
analytical tools.
INTEGRATED ASSESSMENT OF THE IMPACTS OF
CLIMATE CHANGE
4. Practice in integrated assessment
• Most integrated assessment (using modelling) try to find a
proper trade-off between the impacts of climate change and
the impacts of greenhouse gas emission abatement.
• Some integrated assessments pay considerable attention to
the impacts of climate change at global scale, often lacking
detail at regional and country levels. Where models are not
validated against national data, in application to country
studies results of these models should therefore be
interpreted with great care.
• For national studies, existing sectoral integrated assessment
models may be useful for other sectors but this would require
a major investment in time and money.
INTEGRATED ASSESSMENT OF THE IMPACTS OF
CLIMATE CHANGE
4. Practice in integrated assessment
• Integrated approaches are not restricted to building and
applying models, but integrated assessment represents an
attempt to evaluate impacts, costs, benefits and response
options for a sector or place, especially for country studies.
• In other approaches, common analogue and GCM-based
scenarios may be combined with sectoral and integrated
models, interviews and workshops to capture the objectives
of the study.
INTEGRATED ASSESSMENT OF THE IMPACTS OF
CLIMATE CHANGE
5. Possible approaches to integrated impact
assessment
• An approach based on consistent data bases and
scenarios.
• An approach that attempts to avoid overlap and try
to establish consistency between the analyses if the
various sectors, systems, and regions affected by
climate change.
• Approaches using models that are linked so that
important feedbacks are taken into considerations.
INTEGRATED ASSESSMENT OF THE IMPACTS OF
CLIMATE CHANGE
6. Before starting integrated assessment
studies:
• Considerable amount of preparatory
work needs to be done;
• It should involve outreach to and inputs
from people affected by climate change.
• The role of stakeholders should play a
significant part in the assessment.
APPROACHES TO INTEGRATED IMPACT
ASSESSMENT
1. Preparatory stages
a) Define the study area, issues and aims;
b) Establish the integration core team and the
integration; and
c) Find out what has been done to date
1.1 Literature Review
• Integration exercises require information
from the sectoral assessments, and are
intended to address the indirect implications
of climate change.
APPROACHES TO INTEGRATED IMPACT
ASSESSMENT
1.1 Literature Review
• These data requirements are best articulated
early in the research design phase of the country
study.
• Therefore, it is important to find out what has
been done so far in climate impact research in the
country.
• An integrated assessment would best:
 try to build on the findings of earlier impact
research; and
 attempt to draw on the acquired expertise.
APPROACHES TO INTEGRATED IMPACT
ASSESSMENT
1.1 Literature Review
• If found that little impact research has been
conducted,
 it would be advisable to conduct sectoral
studies; and
 place these in an integrative framework right
from the start.
CLIMATE CHANGE IMPACT ASSESSMENT PROCESS: (Sectoral Studies)
Define the scope of the problem (s) and assessment process
Choose scenarios:
Socio-economic
Environmental
Climate change
Conduct biophysical and economic impact assessment and evaluate
adaptive adjustments
Agriculture
Forests
Grassland/Livestock
Water
resources
Coastline
Integrate impact results
Analyze adaptation policies and programs
Document and present results
Other
FRAMEWORK FOR INTEGRATION
Define study area and aims
Establish integration core team, define integrators
Literature review
Is there sufficient knowledge about climate change
impacts and adaptation
Yes? adapt existing analyses to an
integration framework
Revisit existing
studies
Adjust and extend
studies
Redo and novel
studies
Policy scenarios
and communication
strategy
No? do sectoral impact analyzes in
an integration framework
Consistency in scenarios data etc
Consistency between sectors,
systems and regions
Integrated impact analyses from softlinking to integrated modeling
Integrated impact assessment involving policy
makers and stakeholders
Use a common basis:
use compatible GIS,
etc
Avoid overlaps. Use
output of one study as
input to the other
Build compatible
models and submodels
Policy scenarios and
communication
strategy
APPROACHES TO INTEGRATED IMPACT
ASSESSMENT
1.2 Issue focus
In a climate impact assessment, the problems being
addressed are:
• Climate sensitive aspects of ecosystems.
• Resource management;
• Resource extraction operations, or
• Infrastructure maintenance.
Therefore, it is a requirement:
• To make issues clear to participants of the integrated
assessment, so that they know off hand what
questions they are trying to address; and
APPROACHES TO INTEGRATED IMPACT
ASSESSMENT
1.2 Issue focus
• To ensure that climate change is taken into consideration in
areas in which policy is normally made or has been made for
sometime without considering climate change as a factor.
These areas could include:
• The implications of climate change for interjurisdictional
water management;
• Sustainability of ecosystems;
• Economic development of resource-based sectors such as
energy, agriculture, forestry, tourism, fisheries;
• Land use allocation/zoning; and
• Maintenance of transportation facilities
APPROACHES TO INTEGRATED IMPACT
ASSESSMENT
1.3 Study area
• The choice of boundaries depend on the choice of policy
targets.
• It is easier to divide a country by administrative units or
collection of units because of availability of economic data,
(e.g. provinces, planning regions, district assemblies). This is
important because decision making power in vested in such
units.
• Alternatively, ecological zones may be selected (e..g. forest,
savanna, coastal zone) or watersheds.
• It may be appropriate to select watersheds rather than
administrative units if water management is identified as a
policy target for the integrated assessment.
APPROACHES TO INTEGRATED IMPACT
ASSESSMENT
1.4 Integration targets
Integration targets may include:
• Sectoral studies;
• Impacts of climate change in a broader context, such as
involving the relevant stakeholders in the analysis.
• Consistent scenarios and data bases
Notes on approaches
• The goal determines the approach and the resources
required.
• The assessment may begin from more modest goals to the
more ambitious ones.
The second scenarios is important because:
APPROACHES TO INTEGRATED IMPACT
ASSESSMENT
The second scenarios is important because:
 it allows for experience and capacity to be
built up before tackling the more difficult
task of integrated assessment;
 if some difficulties are encountered in the
process if assessment (e.g. availability of
funds because less than anticipated, or
difficulty arises in the conduct of analysis), at
least some goals will have been achieved.
APPROACHES TO INTEGRATED IMPACT
ASSESSMENT
1.5 Integration core team
• The key member of the integration team is the project
leader or team leader.
Project leader or team leader
• Should be able to maintain long-term commitment to the
Integrated assessment.
• To be able to manage better, the project leader should have
experience in climate impacts or environmental impacts
research.
• Project leader should be familiar with regional issues
sensitive to climate.
• Should be able to provide co-ordination needed between
people who are not used to working together.
APPROACHES TO INTEGRATED IMPACT
ASSESSMENT
•
The integration core team should comprise of people of
diverse know-how who are able to provide groundwork
needed with regard to:
 data collection
Scenarios for integrated assessment models
 requisite software for analysis etc.
1.6 Integrators
• An integrator is a system or resource that acts as an
organizing or building principle in an integrated analysis.
• Good integrators connect to a substantial number of other
sectors and systems, and are of prominent interest in their
own right.
APPROACHES TO INTEGRATED IMPACT
ASSESSMENT
Example of integrators
1. The tourist sector on a tropical island
 The tourist sector is a major income earner.
Climate change and sea level rise may affect
the island in the form of:
• incidence of hurricane
• water resources, and
• local agriculture.
All these would affect the profitability of the tourist
sector.
APPROACHES TO INTEGRATED IMPACT
ASSESSMENT
2. A river in a watershed
• This river connects natural and managed
ecosystems, industry and households in their use of
water.
• The idea is to establish a set of integrators in which
various approaches becomes research targets
• It is possible to establish sectoral activities within
the program through:
 setting up a regional or country study in which a
cost-benefit model, settlement development
survey, or land assessment framework are all used
APPROACHES TO INTEGRATED IMPACT
ASSESSMENT
3. Other forms of integrators are:
• Regional or national development plans, since they
are expressions of various trade-offs made by
governments and other stakeholders, accounting for
the domestic natural resource base and external
economic forces.
4. An alternative type of integrator, a common unit of
measuring impacts
Advantages of common units:
• The impacts across sectors and systems can be
aggregated and perhaps compared to other issues
(e.g. air pollution, greenhouse gas mitigation).
APPROACHES TO INTEGRATED IMPACT ASSESSMENT
4. An alternative type of integrator, a common unit of
measuring impacts
Advantages of common units:
•
•
Example of common units is money, which is used to
express trade-offs between valuable goods and services
that are traded on markets.
There are techniques to estimate the monetary values of
goods and services that are not traded, or implicitly
traded.
Disadvantages of common units
•
•
Crucial information may be lost;
Sometimes crude and debatable assumptions need to be
made in order to express impacts in the chosen unit.
APPROACHES TO INTEGRATED IMPACT
ASSESSMENT
Disadvantages of common units
• Because of the great uncertainties and many
assumptions, the results of such exercises should be
interpreted with great care. Particularly in economics
which are not fully commercialized.
5. CONSISTENCY IN SCENARIOS AND DATA
• Consistent scenarios and data bases are the minimum
requirements for integration.
• Comparability of results will be greater if studies
investigate the same scenarios (for climate, population,
economics etc) and use the same reference year, the
same units, and consistent data bases.
APPROACHES TO INTEGRATED IMPACT
ASSESSMENT
5. CONSISTENCY IN SCENARIOS AND DATA
• The climate scenarios can be derived from climate
model simulations, analogues or hypothetical cases.
• The socio-economic scenarios should include
population growth, technological changes, and the
potential economic and political changes that would be
of interest to the region or country over the time
period.
• Scenario data are usually needed in a quantitative form,
particularly of they are used as inputs to models
employed within sectoral and integration activities.
2.2 CONSISTENCY BETWEEN SECTORS, SYSTEMS AND REGIONS
2.2.1 Sectoral impact studies are consistent:
• If the same resource is not assumed to be used
by two sectors at the same time;
• And if climate induced changes in one sector are
included in the study of another sector.
For example
• Water consumed or land occupied by a forest
cannot also be consumed or occupied by
agriculture.
• Climate-induced changes in vegetation upstream
of a river would affect runoff downstream.
2.2 CONSISTENCY BETWEEN SECTORS, SYSTEMS AND REGIONS
2.2.1 Overlaps and inconsistencies between sector
studies should be prevented
Examples of overlaps are:
• Agricultural/ecological and hydrological models
both calculating runoff.
• Models of managed and unmanaged ecosystems
including the same biomes (e.g. semi-managed
forests, extensively grazed grasslands).
• Studies focusing on different aspects of the same
thing (e.g. wildlife versus game for sport
hunting/tourism).
2.2 CONSISTENCY BETWEEN SECTORS, SYSTEMS AND REGIONS
2.2.3. Examples of inconsistencies between sector studies
• Variables incorrectly held constant (e.g. quality of irrigation
water, health status of labour force) and
• Resources that are inherent part of the sectors other than
mere inputs or outputs (for example, land, water and prices).
2.2.4 Therefore, overcoming overlaps and inconsistencies
requires coordination. The nature of coordination is that:
• Agricultural scientists and hydrologists do their analyses
together.
• Interdisciplinary cooperation by developing mutual
understanding, including long discussions about semantics
and paradigms.
• Also, adjustments and concessions need to be made.
2.2 CONSISTENCY BETWEEN SECTORS, SYSTEMS AND REGIONS
2.2.4 Therefore, overcoming overlaps and
inconsistencies requires coordination. The
nature of coordination is that:
• To avoid overlap, one sector needs to yield
part of the analysis to another sector, e.g.
when coupling an ecosystem model with a
hydrological model, only one of the two can
calculate runoff.
• To avoid inconsistencies, part of the sectoral
analysis should be left to other disciplines,
using other methods, models or data.
2.3 EXECUTION OF INTEGRATED IMPACT
ASSESSMENT
1. The Aim:
• To establish a consistent and comprehensive overview of
the impact of climate change on a particular region (e.g.
an island, the coastal zone, a watershed or the whole
country or a particular system or sector (e.g. land use or
tourism), inclusive of the most important feedbacks
between sectors.
2. The Start:
• It is best to start with an analysis of the system
 what are the components of the system?
 what are the links between the components?
What are the issues at stake?
2.3 EXECUTION OF INTEGRATED IMPACT
ASSESSMENT
•
Such ambitions ovals are to help establish a family of integrators,
whose purpose is to provide structure to the analysis.
3. Development of the full scope of the integrated analysis
• After the structure has been determined,
 a description is needed of the components, of the interactions
between the components, particularly the inputs and outputs of
each components, and the type of analysis or model that would
give the required outputs given the inputs.
 such analyses or models may be available. If so, these can be
applied. Otherwise, these will have to be developed as part of the
integration.
 it is at this stage that the final work program and budget can be
made.
2.3 EXECUTION OF INTEGRATED IMPACT
ASSESSMENT
4. Information needs
• Physical, biological and socio-economic studies focusing on one
sector or discipline, provide important information in their own
right.
• There is information need of the resource accounting model, land
assessment framework, community development component, or
legal dimensions component.
5. Two-extremes of doing integrated analysis
• Soft-linking
 soft-linking means that all component analyses stand alone; they
are linked through input and output variables, joint scenarios, and
combined results.
 each component analysis performs its task within strictly
described boundary conditions.
2.3 EXECUTION OF INTEGRATED IMPACT
ASSESSMENT
5. Two-extremes of doing integrated analysis
• Integrated modelling
 integrated modelling combines all
components into a single computer code,
describing the entire system;
 integrated models are not recognized as
separate entities and cannot run without the
whole model.
5. GOALS OF INTEGRATED ASSESSMENT
• The difference between integrated analysis and an
integrated assessment:
 integrated assessment has a policy dimension;
 the design of the assessment is done in
collaboration with scientists, policy makers and
stakeholders;
 in the presentation of the results, there should
be a scientific audience, a lay audience, and a
policy audience;
 it is through the construction of scenarios,
particularly those elements which involve
decisions;
5. GOALS OF INTEGRATED ASSESSMENT
• The difference between integrated analysis and an
integrated assessment:
 an essential element of an integrated assessment is that
light is shed on real-life questions (rather than academic
problems) in a way that is comprehensible and acceptable
to those that have a stake in the issue to be addressed.
5.1 Goals
Goal 1. The first goal of integrated assessment is to study the
potential impacts of climate change on resources and
resource uses e.g. How does climate change affect
agriculture? There is primarily an activity of researchers,
although lay people may also hold considerable knowledge
about particular parts, e.g. water and land use
management practices.
5. GOALS OF INTEGRATED ASSESSMENT
Goal 2. A second goal of integrated assessment is to study the policy
implications of the estimated impacts, e.g. How do changes in
agriculture affect food security? This means evaluation; that is,
the projected outcomes are compared with the aspirations of
citizens, government, etc. here, stakeholders (government
agencies, non-governmental organizations, businesses) may play a
dominant role.
• Alternatively, a specialist may try to measure human preferences,
which are implicitly revealed in everyday decisions, and evaluate
the implications based on that.
Goal 3: A third goal of integrated assessment is to study policy
responses, i.e. “what should be done?” This can be done through
an optimization model. In the case of optimization models, it is
important to select the proper objective functions reflecting the
real aims of the decision makers the model seeks to advise.
INTEGRATED ASSESSMENT – CASE STUDIES
1. THE MINK STUDY
MINK = Missouri, Iowa, Nebraska and Kansas, the
corn belt
Objective
To assess the regional economic implications of
climate change impacts on agriculture, water
resources, forestry and energy use for both
current and projected population and
adaptation technologies.
THE INTEGRATION TOOL
Regional input-output model, IMPLAN
INTEGRATED ASSESSMENT – CASE STUDIES
THE AGENCY: US Department of Energy
THE CORE TEAM
 Scientists from national laboratories (co-sponsored by
government and private sector)
 A non-government research organization (Resources for
the Future, RFF);
 A scientific research society (Sigma XI)
RESEARCH PROGRAM AND TIMEFRAME
A team of scientists from RFF over a three-year period.
TO BEGIN
1. The research team chose the study area, and described
its climate-sensitive attributes and vulnerabilities.
INTEGRATED ASSESSMENT – CASE STUDIES
2. A climate change scenario was constructed from 1930,
and a series of sectoral studies were performed using
this historical analogue, along with estimates of CO2
enrichment.
3. The results of the sectoral studies were used as input to
the IMPLAN Model.
OUTCOME
 Economic impacts were projected to be negative.
 Adaptations were formulated that would offset much of
these losses.
 The result of this process was an estimate, in economic
terms, of direct and indirect impacts of climate change
on an agricultural region.
INTEGRATED ASSESSMENT – CASE STUDIES
 It did not include extensive stakeholder
consultation but it did point the way toward
a process that would enable parallel
assessments of the key sectors to be used as
input to an integrating tool.
 It did not consider some synergism among
the various sectoral impacts, and extent the
water resources assessment so that it would
include the entire watershed rather than just
the MINK portion.
 It did not include environmental implications.
ADVANTAGES OF INTEGRATED ASSESSMENT
• Integrated assessment is a multi-sectoral, multi-disciplinary,
multi-cultural and multi-jurisdictional collaboration and
partnerships. Therefore, it leads to a well-informed,
regional, or country scale research and policy response.
Constraints of Integrated Assessment
• Integrated assessment with stakeholder participation is
difficult to pursue, given the complex and uncertain nature
of climate change issue.
• The assessment involves large study areas, and lack of
immediate climate change data compared with other
regional issues (e.g. poverty, soil degradation, etc.)
• Each region is unique because of its history and geography.
Therefore, integrating different regions is not an easy task.
ADVANTAGES OF INTEGRATED ASSESSMENT
• Given the time and budgetary constraints,
researchers rarely have sufficient time to collect
new data or develop new models. Research will
depend on existing data bases and models for
much of its work, and it will be difficult to
overcome gaps in base information (e.g. climate,
soil, vegetation, population, and economic
transactions).
• Another limitation is that it is difficult to maintain
internal consistency in a large, multi-disciplinary
group (in scales, assumptions, units of measure)
and in ensuring compatibility of various subcomponents.
SUGGESTED GUIDELINES FOR PLANNING A REGIONAL
OR COUNTRY INTEGRATED ASSESSMENT OF CLIMATE
CHANGE IMPACTS
• Attract stakeholders and maintain scientist-stakeholder
collaboration. Allocate time and resources for this purpose.
• The choice of study area will be influenced by political
boundaries, but it is advantageous to consider watersheds
and other ecological boundaries as well.
• It is essential that all scenarios and assumptions are
consistent across the sectoral analyses, or integration will
be hampered.
• A common data platform (e.g. Geographic information
systems (GIS)) should be identified as early as possible.
• Do not avoid personal contacts. Electronic mail will be an
important asset in coordination.