Greenhouse effect

Greenhouse effectWhy should this greenhouse effect be thought of as a problem? The additional warming is what causes concern: • many potentially damaging effects• some beneficial ones

The gases producing this layer around the earth are:• water vapor, • carbon dioxide (CO2), • methane (CH4), • nitrous oxide (NO), • some chlorofluorocarbons (CFCs), and • ozone (O3)

Greenhouse effectThese gases are a mix of natural events and anthropogenic factors determining the relative contributions of these gases is complex

Table 2.1. Contributions of Greenhouse Gases to Global Warming

Type of gasCarbon dioxide

equivalence1990 emissions

(millions of tons)Percentage share

over 100 years

Carbon dioxide 1 26,000 66.0

Methane 21 300 16.5

Nitrous oxide 290 6 4.5

CFCs     12.0

CFC-11 3,500 0.3 n.a.

CFC-12 7,300 0.4 n.a.

HCF-22 1,500 0.1 0.4

Other n.a. n.a. 0.6

Greenhouse effectTwo features:• uncertainty • commitment to some degree of warming.

Two policy responses:• prevention (to reduce trace gas emissions) • adaptation

Greenhouse effectProjected scenarios (IPCC estimates):• scenario A - business as usual: no controls are exercised over

current rates of emission growth global mean temperatures will increase 1°C by 2025 and 3°C by 2100 compared with temperatures in 1990, i.e. a rise of 0.3°C per decade

• scenario B: deforestation is halted, natural gas is substituted for coal, which has a higher carbon content, and energy conservation measures are adopted a rise of 0.2°C per decade

• scenario C: increasingly strict abatement measures are undertaken, and energy from fossil fuels is aggressively replaced by renewable energy warming is held to 0.1°C,

Greenhouse effectTable 2.2. Possible Change in Climate, by Region and Season (scenario A)

Region and Latitude

Temperature change as a multiple of global average

Rainfall

Summer Winter

Arctic and Antarctic areas (60°-90°)

0.5-0.7 2.0-2.4Enhanced in winter

Major food-growing regions of North America and Europe (30°-60°)

0.8-1.0 1.2-1.4Possibly reduced in summer

Much of developing world (0°-30°)

0.9-1.7 0.9-1.7Enhanced in places that have heavy rains today

Effects of global warmingProjected scenarios (IPCC estimates):• Rise in regional temperature: mid-latitude regions

– summer soil moisture may be reduced, and crops could be affected by summer droughts;

– reduction of water supplies, both of surface water and groundwater aquifers– changes in hydrological regimes

• Rise in sea level: melting mid- and high-latitude small glaciers and ice sheets mean rise in sea level of 6 cm a decade

– loss of low-lying land to the sea– salt intrusion to freshwater systems and groundwater– storm surges that cause floods

• Frequent and severe events: alteration of the frequency and variability of events related to the weather

– droughts, storms, and floods may be more frequent and severe

Effects on LDCs• LDCs more dependent than DCs on NR more sensitive to

changes in climate• the agricultural systems of many LDCs are based on low-lying

deltaic land flooding and saltwater intrusion• many agricultural systems rely on natural rainfall rather than

irrigation systems problems with changes in rainfall patterns• many small LDCs are island communities at special risk from

severe weather events such as hurricanes and cyclones • the very poverty of many LDCs will preclude them from

undertaking the adaptive policies, such as sea defenses, that may be needed

Ozone layer depletion Stratospheric ozone blocks ultraviolet radiation from the sun depletion of the ozone layer increases the incoming UVR:• increase of skin cancers• suppressions of the immune system in the human body• eye disorders• reduced or distorted growth in plants

Cause (mid 1970s): chlorofluorocarbons (CFCs)• depletion of the ozone layer • contribute to global warming

1989: Montreal Protocol

Loss of Biodiversity Biodiversity is the totality of genes, species, and ecosystems. The term is helpful for reminding us that it is not just the total stock of living things that matters, but the range of different living things.

Protecting the world’s biodiversity is a difficult task:• 30-50 million species • only 1.43 million species have been scientifically described• most undescribed species inhabit the tropical forests • rate of loss of species is not known, but evidence suggests that the

rate of extinction has increased • perhaps one-quarter of existing species are at risk of extinction in

the next twenty to thirty years

Loss of Biodiversity Table 2.3. Status of Threatened Species

Species Extinct Endangered Vulnerable Rare Indeterminate Total

Amphibians 2 9 9 20 10 50

Birds 113 111 67 122 624 1,037

Fish 23 81 135 83 21 343

Invertebrates 98 221 234 188 614 1,355

Mammals 83 172 141 37 64 497

Plants 384 3,324 3,022 6,749 5,598 19,078

Reptiles 21 37 39 41 32 170

Loss of Biodiversity

Causes of biodiversity loss:• population growth, • ill-defined land and resource rights, • market, planning, and government failures

If the above factors explain habitat loss, • their reversal or containment will assist the conservation process,

but• in order to avoid to alienate people, it is required community

involvement in protected areas

The Mediterranean Basin

Why the Mediterranean Sea is subject of environmental concern?• land-locked • surrounded by countries with various combinations of

– rapid population growth, – industrialization, – development, – massive changes in land use

Two kinds of problems (Box 3.1):• common problems, i.e. they are shared by two or more countries• problems occuring separately in several countries

The Mediterranean Basin

Both types of problems are reciprocal externalities that require bilateral or collective action

Examples: • heavily polluted rivers• declining fisheries (because of pollution as well as over-fishing)• reduced wetland areas (because of land reclaimation,

urbanization)• loss of forests and natural habitats• water deficiencies and water quality problems• soil depletion (overgrazing, overcultivation, salinization, water-

logging)• solid waste poorly managed

The Mediterranean Basin Causes :• population growth: by 2025 the 1985 population of 350 million persons could have increased by 200 million

• economic policy: energy and irrigation are subsidized • institutional failure: tenurial arrangements, weak controls over development, poor political awareness of environmental issues

Actions:• contain population pressure on natural resources• reduce tenurial conflicts• getting resource prices right (i.e. reflect social costs) • strengthen institutions

Water Resources in the Middle East

Why the water resources are so important for the Middle East? No other region of the world embraces such a large area, with so many people striving so hard for economic growth on the basis of so little water

The Mashrek lies in a transition zone. The dominant hydrological characteristic is the combination of:• aridity and • uncertaintyWhereas regions of higher rainfall sometimes suffer droughts and regions of lower rainfall sometimes experience floods, this region has to cope with both

Water Resources in the Middle East

Water Resources in the Middle East

Water Resources in the Middle East

Three water crises at the same time:• quantity: demand for fresh water in the region exceeds the

naturally occurring, renewable supply• quality: much of the region’s limited water is being polluted from

growing volumes of human, industrial, and agricultural wastes• equity: the same water is desired simultaneously by different

sectors in some society or wherever it flows across (or under) an international border

Water Resources in the Middle East

Actions:• quantity: much more attention should be paid to the low-capital-

decentralized options than to the high-capital-centralized ones. To a large extent, the former are not only technically proven but typically more cost effective, given the marginal costs of new conventional water supply

• quality: intervene to fix the major causes of pollution, i.e. overpumping of aquifers, runoff from agriculture, discharge of human and industrial wastewater, and loss of habitat

• equity: develop internal as well as international institutions to manage conflicts

Land Degradation and Desertification

What is land degradation? • soil erosion• waterlogging• salinization • land use change

What is desertification? land degradation in arid, semi-arid and dry sub-humid areas resulting from various factors, including climatic variations and human activities

Land Degradation and Desertification

Why is land degradation a problem? • during the 1980s, the amount of per capita arable land declined by

1.9% per annum • that is, every year, around 70,000 km2 of farmland are abandoned

because the soils are too worn out and degraded for crop production; another 200,000 km2 suffer from reduced productivity

• about 1.4 billion hectares of arable land have been taken out of agricultural production because of urban sprawl between 1980 and the turn of the century

• overall land degradation of various sorts is estimated to be causing an annual loss of 12 million tons of grain output: almost half of all the gains in grain output each year

Land Degradation and Desertification

Why is desertification a problem? • one-third of the earth’s land is arid or semi-arid • some 600 million people live there• more than 20% of the earth - home to 80 million people - is

directly threatened by desertification• some 100 countries are affected.

Land Degradation and Desertification

Causes of land degradation/desertification:• population growth: populations are increasing as fast in arid lands as elsewhere

• overcultivation, • overgrazing, • deforestation, • poor irrigation

people takes too much from the soil and puts too little back

Traditional rainfed cropping systems break down under pressure from growing populations and the increased planting of cash crops

The Human-Environment Relationship

THE ECONOMY

Firms(Production)

Households(Consumption)

Inputs Outputs

THE ENVIRONMENT

ENERGY

AIR

WATER

AMENITIES

AIRPOLLUTION

SOLIDWASTE

WASTEHEAT

WATERPOLLUTION

RAWMATERIALS

Functions of the Environment• Source of raw materials:

– depletable– renewable

• Sink for waste:– biodegradable/short-lived/non-toxic– toxic/persistent

• General life support:– water cycle– carbon cycle– ozone layer

The First Two Laws of Thermodynamics

First law of termodynamics: energy and matter cannot be created or destroyed

– the mass of materials flowing into the economic system has to either accumulate in the economic system or return to the environment as waste

– excessive wastes can depreciate the asset: limited absorptive capacity

Second law of termodynamics: entropy increases – no conversion from one form of energy to another is completely efficient and

that the consumption of energy is an irreversible process – over the very long run, the growth process will be limited by the availability

of solar energy and our ability to put it to work

Closed vs. open systems: exchange of energy and matter

Earth as a closed system

A Classification of Natural Resources

What is a resource?• utility vs. altruism• natural vs. man-made• renewable vs. non-renewable (or exhaustible): - growth and reproduction - carrying capacity (max stock) - rate of extraction• conditionally vs. uncoditionally renewable

A Classification of Natural Resources Natural resources

Renewable Non-renewable

Unconditionallyrenewable

Conditionallyrenewable

Non-biologicalflow resources

Non-biologicalcycling resources

Simple biologicalresources

Complexresources

•oil•coal•minerals

•solar energy•tidal energy•wind energy

•water•nitrate•CO2•O2

•mammals•fish•crops

•soil•ecosystems

Special Features of Agricultural Resources

What are, if any, the special features of agricultural resources?• inter-temporal or long-run nature optimal time path of use uncertainty• close linkages between the physical system and biological system• complexity of involved resources renewable + exhaustible quality differentiated• spatial nature of resources

Ideas of Development

1950s-60s: economic growth 1960s-70s: growth with redistribution1970s-80s: basic needs1980s-90s: sustainable development

Sustainablity is concerned with thes ‘3 Es’:• economic dimension: efficiency • ecological dimension: ecosystem functioning and environment

maintenance• equity and ethical dimension: distributional consequences of

policy alternatives

Views on Sustainable Development

“Sustainable economic development involves maximizing the net benefits of economic development, subject to maintaining the services and quality of natural resources over time” (Pearce et al., 1987)

“Sustainable economic development … refers to the optimal level of interaction between three systems - the biological, the economic and the social - through a dynamic and adaptive process of trade-offs” (Barbier, 1989)

a) Economists:

Views on Sustainable Development

“Sustainability (is) the ability to maintain productivity, whether as a field, farm or nation, in the face of stress or shock” (Conway and Barbier, 1990)

“Sustainable development based on prevailing patterns of resource use is not even theoretically conceivable ... a new definition of sustainable development … is development that minimizes resource use and the increase in global entropy” (Rees, 1990)

b) Ecologists:

Views on Sustainable Development

Demand on the environment that are culturally determined … Are the institutions which are used to manage the environment subject to local control and have they evolved to meet local needs?

The underlying global economic and political factors which encourage environmental degradation need to be addressed, and a global redistribution of wealth has to occur. Only then can sustainable development on a global scale become a realistic possibility.

c) Sociologist:

Views on Sustainable Development

“Development that meets the needs of the present without compromising the ability of future generations to meet their own needs” (WCED, 1987)

Two different meanings:• the stock of natural capital in particular must be left intact for the

next generation• the aggregate stock of manufactured and natural capital must not

decline between one generation and the next trade-offs

Brundtland Commission

Views on Sustainable Development

“Sustainable Development is the management and conservation of the natural resource base, and the orientation of technological and institutional change in such a manner as to ensure the attainment and continued satisfaction of human needs for present and future generations. Such sustainable development (in the agriculture, forestry and fisheries sectors) conserves land, water, plant and animal genetic resources, is environmentally non-degrading, technically appropriate, economically viable and socially acceptable” (FAO, 1989)

FAO

Agriculture in Economic Development Green revolution:• Objectives:

– increasing per capita income – rising per capita food production

• Three interrelated actions:– staple cereals that produced early maturing, day-length

insensitive and high-yielding varieties (HYVs) – packages of high payoff inputs, such as fertilizers, pesticides

and water regulation – implementation in the most favorable agro-climatic regions and

for farmers with the best expectations of realizing the potential yields

Agriculture in Economic Development Post green revolution problems:• equity:

– widely adopted irrespective of farm size and tenure– soil quality, access to irrigation water, etc. have been

formidable barriers to adoption• stability:

– monocropping associated with increased output variability (pests, diseases, and weeds)

– year-to-year fluctuations in input use arising from shortages or price changes

• productivity:– diminishing returns to the HYVs and high pay-off inputs

Agriculture in Economic Development A new phase in Ag Dev?: Agricultural Sustainable Development• World Bank: ‘successful’ Ag Dev

1. sustainable, by insuring the conservation and proper use of renewable resources

2. promote economic efficiency3. its benefits must be distributed equitably

• CGIAR:– technological and research priorities to make agricultural

production in the Third World more sustainable• IFAD:

– strategies for implementing sustainable Ag Dev in resource poor environments

– strategies for spreading benefits to the rural poor

Agricultural Sustainability

RESOURCES

Human

Man-made

Natural

AGRICULTURE PRODUCTSFood and fiber

INTERNATIONALAND NATIONAL

POLICIES

Farmer andcommunity

decision-makingNATIONALECONOMY

INDIVIDUALLIVELIHOOD

Agricultural Sustainability

A) The sustainability of resources:• renewable vs. exhaustible resources husband renewable

resources in such a way as to provide a long-term sustainable base for production

• frontier and poor societies unsustainable resources use, that is intensive application of:- capital- technology - (labor)

• LDCs cannot afford the technological investment, nor do they have dependent countries which they can exploit

Agricultural Sustainability

B) Mismatched technologies :• within the agricultural production system lack of knowledge or

appropriate skills low efficiency higher costs• outside the agricultural production system agrochemicals

human diseases, pollution, etc.

What is agricultural sustainability?The ability to maintain productivity, whether of a field or farm or nation, in the face of stress or shock ( resilience). A stress may be increasing salinity, or erosion, or debt; etc.

Agricultural Sustainability a) Sustainability ( resilience)

time

agri

cultu

ral p

rodu

ct

shock

high

low

Function of:• the intrinsic characteristics

of the system, • the nature and strength of

the stresses and shocks,• the human inputs which

may be introduced to counter these stresses and shocks

Agricultural Sustainability b) Productivity

time

agri

cultu

ral p

rodu

ct

high

low

Output of valued product per unit of resource input :• land (solar energy),• labor (human energy),• capital (fossil fuel energy)

Agricultural Sustainability c) Stability

time

agri

cultu

ral p

rodu

ct

high

low

The constancy of productivity in the face of small disturbing forces arising from the normal fluctuations and cycles in the surrounding environment:• climate,• market demand,• etc.

Agricultural Sustainability d) Equitability

high

low

agricultural product

num

ber

of b

enef

icia

ries The evenness of distribution

of the productivity of the agricultural system among the human beneficiaries

Trade-offs

Agricultural Sustainability e) Efficiency

Maximum economic efficiency is equivalent to maximum profit

Input (X)

RevenueCost

X*

TR

TC

QMAX

XMAX

max Maximization with

sustainability constraints

Spatial and Hierarchical DimensionsWorld

Country

Region

Watershed

Village

Household

Livelihood system

Farming system

Livestock system

Paddock

Herd

Animal environment

Cropping system

Field

Crop

Plant environment

Gathering& hunting

Handicraftmanifacture

Off-farmemployment

Trading

Trade-offs