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

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.

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.

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.

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
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 North-east 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 mid-latitudes.

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 temperatures Rainfall: heavy all year (convectional) High amount of cloud cover High humidity Savanna High 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

TEMPERATURE AND PRECIPITATION
CLIMATE TYPE TEMPERATURE AND PRECIPITATION HUMID MID-LATITUDE Mediterranean Warm to hot summers Mild to cool winters Dry summer Frontal precipitation in winter Generally low humidity Humid Subtropical Hot summers Mild winters Convectional showers in summer 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

CLIMATE TYPE TEMPERATURE AND PRECIPITATION ARCTIC AND SUBARCTIC Subarctic; Tundra Ice Cap Cool to cold short summers Extremely cold winters Dry climate with some summer and winter precipitation HIGHLANDS Great variety of conditions based on elevation, prevailing winds, sun-or 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. 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 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
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

N2O Oceans, Tropical soils, Temperate soils
Gas Natural Source Anthropogenic Source N2O Oceans, Tropical soils, Temperate soils Nitrogen fertilizers, Industrial sources, adipic acid/nylon, nitric acid, landuse change (biomass burning, forest clearing) CFCs 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 micro-organisms into simple molecules for absorption into the blood stream. Both ruminants (e.g. cattle, sheep) and non-ruminants (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
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.

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.

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.

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.

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
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. 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%) (0.25%) Atmospheric lifetime (yr) 10 150

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). plants consume CO2 in photosynthesis as a source of carbon to grow and emit O2. 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

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.

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 impacts
ANALYSIS OF CLIMATE CHANGE, CLIMATE VARIABILITY AND FUTURE FOOD SECURITY 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.

Climate change Scenarios
ANALYSIS OF CLIMATE CHANGE, CLIMATE VARIABILITY AND FUTURE FOOD SECURITY 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) 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.

(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.

(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

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

Conservation of energy (first law of thermodynamics) dI/dt = –ρ Q Where: I = internal energy per unit mass Q = heating rate per unit mass

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
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
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 model-produced 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 Stochastic simulation of daily precipitation, temperature and solar radiation. Water Resources Research, 17: 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: 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: 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.

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

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.

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.

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.

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.

Changing cropping sequences;
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.

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.

increased investment in agricultural infrastructure;
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.

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.

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.

what is the range of choices for adapting to climate change?
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?

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 yield-enhancing 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.

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

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.

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.

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.

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).

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).

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.

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).

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

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

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

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

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.

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.

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.

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.

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.

The adaption of such cultivars by farmers depends on:
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
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 in the study of climate change impacts on agriculture also the decision-making process depends on choices, and economic well-being 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 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: 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

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.

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

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.

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.

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.

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
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.

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.

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:

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.

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
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)

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.

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.

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.

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.

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.

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.

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.

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
Preparatory stages Define the study area, issues and aims; Establish the integration core team and the integration; and 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.

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.

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 Conduct biophysical and economic impact assessment and evaluate adaptive adjustments Agriculture Forests Grassland/Livestock Water resources Coastline Other Integrate impact results Analyze adaptation policies and programs Document and present results Choose scenarios: Socio-economic Environmental Climate change

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 No? do sectoral impact analyzes in an integration framework Consistency in scenarios data etc Consistency between sectors, systems and regions Integrated impact analyses from soft-linking to integrated modeling Integrated impact assessment involving policy makers and stakeholders Revisit existing studies Use a common basis: use compatible GIS, etc Adjust and extend studies Avoid overlaps. Use output of one study as input to the other Redo and novel studies Build compatible models and sub-models Policy scenarios and communication strategy

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

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

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.

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:

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.

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.

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.

Example of integrators 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.

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

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).

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.

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.

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.

2.2.1 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).

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.

2.2.4 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
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?

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.

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.

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;

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.

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
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

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 The research team chose the study area, and described its climate-sensitive attributes and vulnerabilities.

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. 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.

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 sub-components.

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.

CS 755: CLIMATE, AGRICULTURE AND ENVIRONMENT

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