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Greenhouse effect

Greenhouse effect

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Greenhouse effect

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  1. Greenhouse effect

  2. Greenhouse effect • Whyshould this greenhouse effect be thought of as a problem? • The additional warming is what causes concern: • many potentially damaging effects • somebeneficial 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)

  3. Table 2.1. Contributions of Greenhouse Gases to Global Warming Type of gas Carbon dioxide equivalence 1990 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 effect These gases are a mix of natural events and anthropogenic factors determining the relative contributions of these gases is complex

  4. Greenhouse effect • Two features: • uncertainty • commitment to some degree ofwarming. • Two policy responses: • prevention (to reduce trace gas emissions) • adaptation

  5. Greenhouse effect • Projected 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,

  6. Table 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 2.0-2.4 Enhanced in winter Major food-growing regions of North America and Europe (30°-60°) 0.8-1.0 1.2-1.4 Possibly reduced in summer Much of developing world (0°-30°) 0.9-1.7 0.9-1.7 Enhanced in places that have heavy rains today Greenhouse effect

  7. Effects of global warming • Projected 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 • andice 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

  8. Effects on LDCs • LDCs more dependent than DCson 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

  9. 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

  10. 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 adifficult 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 suggeststhat the rate of extinction has increased • perhaps one-quarter of existing species are at risk of extinction in the next twenty to thirty years

  11. 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

  12. 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

  13. The Mediterranean Basin • Why the Mediterranean Sea is subject of environmentalconcern? • 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

  14. The Mediterranean Basin Both types of problems are reciprocal externalities that require bilateral or collectiveaction • 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

  15. The Mediterranean Basin • Causes: • populationgrowth: by 2025the 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: • containpopulation pressure on natural resources • reduce tenurial conflicts • getting resource pricesright (i.e. reflect social costs) • strengthen institutions

  16. 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 • uncertainty • Whereas regions of higher rainfall sometimes suffer droughts and regions of lower rainfall sometimes experience floods, this region has to cope with both

  17. Water Resources in the Middle East

  18. Water Resources in the Middle East

  19. 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

  20. 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 internalas well as international institutions to manage conflicts

  21. 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

  22. 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

  23. 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.

  24.  Land Degradation and Desertification • Causesof land degradation/desertification: • populationgrowth: populations are increasing as fast in arid lands as elsewhere • overcultivation, • overgrazing, • deforestation, • poor irrigation Traditional rainfed cropping systems break down under pressure from growing populations and the increased planting of cash crops people takes too much from the soil and puts too little back


  26. 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

  27. The First Two Laws of Thermodynamics Closed vs. open systems: exchange ofenergyand matter Earth as a closed system • 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

  28. 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

  29. A Classification of Natural Resources Natural resources Renewable Non-renewable • oil • coal • minerals Unconditionally renewable Conditionally renewable Non-biological flow resources Non-biological cycling resources Simple biological resources Complex resources • solar energy • tidal energy • wind energy • water • nitrate • CO2 • O2 • mammals • fish • crops • soil • ecosystems

  30. Special Features of Agricultural Resources • What are, if any, the special featuresof agriculturalresources? • inter-temporal or long-run nature • optimal time path of use • uncertainty • close linkagesbetween the physical system and biological system • complexity of involved resources • renewable + exhaustible • quality differentiated • spatial nature of resources

  31. Ideas of Development 1950s-60s: economic growth 1960s-70s: growth with redistribution 1970s-80s: basic needs 1980s-90s: sustainable development • Sustainablityis concerned with thes ‘3 Es’: • economicdimension: efficiency • ecologicaldimension:ecosystem functioning and environment maintenance • equity and ethicaldimension:distributional consequences of policy alternatives

  32. Views on Sustainable Development a) Economists: “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)

  33. Views on Sustainable Development b) Ecologists: “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)

  34. Views on Sustainable Development c) Sociologist: 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.

  35. Views on Sustainable Development Brundtland Commission “Development that meets the needs of the present without compromising the ability of future generations to meet their own needs” (WCED, 1987) • Twodifferent 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

  36. Views on Sustainable Development FAO “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)

  37. 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

  38. 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

  39. Agriculture in Economic Development • A new phase in Ag Dev?: Agricultural Sustainable Development • World Bank: ‘successful’ Ag Dev • sustainable, by insuring the conservation and proper use of renewable resources • promote economic efficiency • 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 sustainableAg Dev in resource poor environments • strategies for spreading benefits to the rural poor

  40. INTERNATIONAL AND NATIONAL POLICIES Farmer and community decision-making NATIONAL ECONOMY INDIVIDUAL LIVELIHOOD Agricultural Sustainability RESOURCES Human PRODUCTS Food and fiber Man-made AGRICULTURE Natural

  41. 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

  42. 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.

  43. agricultural product high shock low time Agricultural Sustainability a) Sustainability ( resilience) • Function of: • the intrinsiccharacteristics 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

  44. high agricultural product low time Agricultural Sustainability b) Productivity Output of valued product perunit of resource input : •land (solar energy), • labor (human energy), •capital (fossil fuel energy)

  45. high agricultural product low time Agricultural Sustainability c) Stability 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.

  46. high number of beneficiaries low agricultural product Agricultural Sustainability d) Equitability The evenness of distribution of the productivity of the agricultural system among the human beneficiaries Trade-offs

  47. Revenue Cost TR QMAX max p TC XMAX X* Input (X) Agricultural Sustainability e) Efficiency Maximum economic efficiency is equivalent to maximum profit Maximization with sustainability constraints

  48. World Country Region Watershed Village Household Livelihood system Gathering & hunting Handicraft manifacture Farming system Off-farm employment Trading Livestock system Cropping system Field Paddock Herd Crop Plant environment Animal environment Spatial and Hierarchical Dimensions Trade-offs