Topic 2Global Environmental Changes

Dr. ANWAR AHMAD

Environmental Engineering

OBJECTIVES

• i) Introduce the cause of human activity to global environment

• ii) Expose students on negative Anthropogenic and natural effects to the biosphere.

• iii) To provide a basic idea how to handle the environmental problems.

Evidence for large scale fluctuations in temperature and changes in sea level

• Events called Heinrich iceberg events occurred at least six times during the last glacial. These events were marked by sudden increases in the number of icebergs in the Atlantic (evidence comes from sediments transported by the ice and deposited on the ocean bed). They were caused by sudden collapse of the North American ice cap. This occurred when the ice was at its thickest, trapping geothermal heat at its base. This heating caused basal melting and sudden surges of ice movement. The sudden release of fresh water into the Atlantic shut off the North Atlantic Salinity Sink, causing a cooling of northern Europe.

• An unexplained feature of the glacials is that tropical oceans appear to have been warmer by about 2oC than during the interglacials. The changes in ocean circulation causing this are not understood.

SUMMARY

• The causes of ice ages are complex and not yet fully understood. It is now recognised, however, that the most significant single factor is the fluctuation in insolation (the sun's radiation on the Earth) resulting from cycles in the Earth's orbital parameters. Changes in the Earth's orbital eccentricity, obliquity and precession of the equinoxes occur with periods of 96,000, 41,000 and about 21,000 years (the Milankovitch cycles, see below). The relationship between these cycles and climate may be examined by determining the power spectrum of the 18O signal from ocean cores.

EARTH TEMPERATURE

Climate Change

• climatic averages of the common weather variables, such as temperature, rainfall, sunshine and atmospheric pressure, are calculated over a 30 year period. The effect of year-to-year irregularities can then be removed by various mathematical techniques, to reveal possible trends in climate.

Climate Change CausesNatural Causes

• There are many causes of climate change. Many are natural and involve processes which influence the flows of energy into, out of and within the climate system, such as changes in ocean circulation and changes in the amount of energy received by the Sun.

Anthropogenic Causes• Recently however, concern has grown that mankind's pollution of the atmosphere

may be causing global-scale changes in climate, with accompanying shifts in regional climate regimes all over the world. By increasing the amount of greenhouse gases in the atmosphere through the burning of fossil fuels and deforestation, we have enhanced the Earth's natural greenhouse effect.

Current Scenario• During the last 100 years, the Earth's average surface temperature (about 15°C) has

increased by over 0.5°C, much of the rise occurring since the 1980s. Whilst this global warming does not seem very much, further increases in greenhouse gas emissions may increase the warming by a further 2 to 3°C over the next 100 years. This change should be compared to the 5°C warming that occurred over a period of about 5,000 years at the end of the last Ice Age 14,000 years ago.

Physical Processes important in Climate formation

1) Atmospheric and oceanic circulation: involves the equations of motion for a fluid (air or water). These represent Newton's second law (`F=ma'), mass conservation for the fluid and some thermodynamic relationships: they take the form of nonlinear partial differential equations.

2) Atmospheric radiation budget: models of atmospheric radiation rely on calculating the radiation absorbed, transmitted, reflected and scattered by each level of the atmosphere, in each wavelength band. These processes are sensitive to the composition of the atmosphere, which varies in time and position

3) Hydrology, and water phase changes are extremely important. Notably, the microphysics of cloud droplets and ice crystals, on scales of fractions of a millimetre, influence the macroscopic behaviour of cloud systems, on scales of 10's to 1000's of km.

4) Chemical reactions in the atmosphere and ocean affect the composition of the system, which in turn feeds back on the radiation balance and the biosphere.

5) Energy flow in rocks and soils is critical in determining, the surface temperature, which in turn affects the magnitude of the OLR. Heat fluxes in soils, in particular, is sensitive to the nature of the soil, which can vary over short distances, and the soil moisture, which is strongly varying in time and space (as well as being affected by plant development).

6) Biosphere processes are generally poorly understood.

Human Activities on Biosphere

.Global warming

Deforestation

Ozone layer depletion

Industrialisation

Agricultural Activities

Motor VehiclesMicro Climatical changes (Urban Heat Island)

Desert formation

Urbanization & population growth

Air Pollution

Species Loss

Anthropogenic heat generation

BIOSPHERE

Change in Land use

Urbanization & Population Growth

• Definition• Urbanization is the increase over time

in population or extent of cities and towns. Urbanisation has profound effects on the ecology of a region and on its economy. Urban sociology also observes that people's psychology and lifestyles change in an urban environment

• The rate of urbanisation over time is distinct from the rate of urban growth, which is the rate at which the urban population or area increases in a given period relative to its own size at the start of that period. The urbanisation rate represents the increase in the proportion of the urban population over the period.

Urbanization and Effects• b) Effects on the Hydrosphere and Water

ResourcesUrbanization has a great effect on hydrology, for a number of reasons.

• Flow of Water into Streams  As cities grow, natural groundcover changes dramatically. Natural vegetation and undisturbed soil are replaced with concrete, asphalt, brick, and other impermeable surfaces. This means that, when it rains, water is less likely to be absorbed into the ground and, instead, flows directly into river channels. Not only does more water reach the stream channels, but it arrives far more quickly after a storm. Natural vegetation slows run-off, concrete and asphalt speed the flow. The result diagrammed below indicates how urbanization speeds run-off and produces higher peaks of flow.

EFFECT A) Erosion and other changes in land quality  Rapid development can result in very high levels of erosion and sedimentation in river channels.

• B) Degraded Water Quality

These changes in the flow of precipitation into and through urban watersheds holds a number of consequences of water quality.

i) Increased sedimentation

•  An increased area of exposed and soils and higher runoff speeds means that more sediments are carried into local and downstream watersheds. This leads to increased rates of sedimentation.

• ii) Pollutants in runoff

•  As water washes across urban surfaces, it dissolves and carries pollutants into streams and rivers. Toxic chemicals, oil, and other pollutants are all deposited in the watershed, sometimes in sediments. Also, most cities use rivers to dispose of the affluent from sewage treatment. Nowadays, it is relatively rare in the United States for untreated sewage to be discharged into waterways since storm and sanitary sewers have been divided for the most part into separate systems, but it does happen from time to time. Chemical tests of water samples are often required to identify pollutants but, sometimes, the color and smell of the water provide clues.

Effects

Mitigations • i) Methods for Controlling Flooding •  Often humans intervene to speed the flow of water through stream

channels and to control erosion. Many different methods exist to control flooding and the flow of streams.

• 1)Banks may be reinforced with plants, rock, or concrete retaining walls.• 2)In extreme cases, a stream may be "channelized," that is totally lined with

concrete.

• ii) Encroachment of Flood Plains •  As they grow, cities also tend to encroach on flood plains. These are low-

lying areas that can hold and absorb overspill from stream during periods of high water. This encroachment of courses places humans in the way of floods. But encroachment also effects a watershed's ability to manage waterflow naturally. Excess flow may be kept out of floodplains by forcing extra flow downstream at higher speeds, with obvious consequences. Erosion and down-cutting will increase and the danger to downstream communities will increase.

1) Urban heat island(micro climatical changes)

• Definition

An urban heat island (UHI) is a metropolitan area which is significantly warmer than its surroundings. As population centers grow in size from village to town to city, they tend to have a corresponding increase in average temperature, which is more often welcome in winter months than in summertime. The EPA says: "On hot summer days, urban air can be 2-10°F [2-6°C] hotter than the surrounding countryside. Not to be confused with global warming, scientists call this phenomenon the 'urban heat island effect' R. W. Buechley et. al (1972).

Causes of the urban heat island effect

(i) Increased anthropogenic heat release• Heat release resulting from energy consumption in urban areas

(ii) Changes in surface cover Reduced surface evapotranspiration capacity due to less green area

(iii) The heat storage effect of construction materials such as concrete and asphalt

(iv) Urban structure *Heat stagnation due to densely packed buildings *Expansion of urban areas

(v) OtherThe greenhouse effects of fine-particulate air pollution in the urban atmosphere

a) The Creation of Heat Islands •  Cities are made of concrete, asphalt, brick, stone, and steel.

These materials absorb and reflect energy differently than vegetation and soil. They absorb more radiant energy and radiate this energy back into the atmosphere at different times through the day. The result is that cities are warmer than the surrounding countryside, sometimes considerably. Furthermore, cities remain warm well into the night when the countryside has already cooled.

• This heat influences air circulation and patterns of precipitation

Urban heat island (UHI) Effect

UHI (Urban Heat Island)

Thermal (top) and vegetation (bottom) infrared satellite data measured by NASA’s Landsat 7 Enhanced Thematic Mapper Plus on August 14, 2002, one of the hottest days in New York City's summer. A comparison of the images shows that where vegetation is dense, temperatures are cooler.

UHI Mitigation

a)The heat island effect can be counteracted slightly by using white or reflective materials to build houses, pavements, and roads, thus increasing the overall albedo of the city.

b)A second option is to increase the amount of well-watered vegetation.

c)These two options can be combined with the implementation of green roofs.

Air Pollution• Definition: pollution is a broad term applied to any chemical, physical (e.g. particulate

matter), or biological agent that modifies the natural characteristics of the atmosphere .

• Some air contaminants can damage human health. These often have guidelines stating the highest average amount that can be present in air over a period of time, for example 24 hours.

• Other contaminants are a nuisance because they reduce our enjoyment of the environment, affecting visibility or creating odours. Usually there are no guidelines for these contaminants.

• Particulate matter• Carbon monoxide (CO) • Carbon dioxide (CO2)• Methane (CH4)• Nitrogen oxides (NOx) • Sulphur oxides (SOx)• Hydrogen sulphide (H2S)• Lead (Pb)• Volatile organic compounds (VOCs)• Odour• Agrichemicals• Ozone (O3)

Types of Air Pollutant from Anthropogenic activities

Chlorine

Chlorofluorocarbons CFCs

Ground level Ozon O3

Particulate Matters

DDT, Pesticide & Herbicide

DustCarbon Dioxide CO2

Halon

Heavy MetalMercury, Lead, Arsenic

Smoke

Carbon Monoxide CO

Sulfur Oxides SOX

BIOSPHERE

Methane Gas CH4

Acid Rain

Nitrous Oxide NOX

ATMOSPHERE & CLIMATE

Sources • Anthropogenic sources (human activity) related to burning different kinds of fuel• Using a controlled burn on a field in South Georgia in preparation for spring planting.• Combustion-fired power plants. • Controlled burn practices used in agriculture and forestry management • Motor vehicles generating air pollution emissions. • Marine vessels, such as container ships or cruise ships, and related port air emissions • Wood, coal, fuel oil or natural gas burning fireplaces, stoves, furnaces and incinerators,

• Other anthropogenic sources• Oil refining, power plant operation and industrial activity in general. • Chemicals, dust and crop waste burning in farming, (see Dust Bowl). • Fumes from paint, varnish, aerosol sprays and other solvents. • Waste deposition in landfills, which generate methane • Military uses, as nuclear weapons, toxic gases, germ warfare and rocketry.

• Natural Sources• Dust from natural sources, usually large areas of land with little or no vegetation. • Methane, emitted by the digestion of food by animals, for example cattle. • Pine trees, which emit volatile organic compounds (VOCs). • Radon gas from radioactive decay within the Earth's crust. • Smoke and carbon monoxide from wildfires. • Volcanic activity, which produce sulfur, chlorine, and ash particulates.

Carbon monoxide (CO)

• Carbon monoxide (CO) • Carbon monoxide (CO) is a poisonous gas that’s colourless, odourless and

tasteless. It’s poisonous because it attaches to our red blood cells better than oxygen - reducing the blood’s ability to carry oxygen around the body. Low exposure to carbon monoxide causes headaches, dizziness and nausea. High exposure can lead to death.

• Carbon monoxide is generally found at levels that are of concern in urban areas where there are high-density housing and busy roads.

• Normally, when there is plenty of oxygen present burning fuel will give off carbon dioxide (CO2). The carbon (C) comes from the fuel and the oxygen (O2) comes from the air. But, when there’s not enough oxygen present, only one oxygen molecule binds with a carbon – forming carbon monoxide (CO).

• The national guideline for carbon monoxide is:• 30 mg/m3 as a one hour average• 10 mg/m3 as an eight hour average. • Find out about carbon monoxide as an indicator of air quality.

Carbon dioxide (CO2)

• Carbon dioxide (CO2)• Carbon dioxide (CO2) is a greenhouse gas that’s colourless and

odourless. Carbon dioxide is being constantly circulated in the environment. It’s naturally released by:

• animal respiration• decomposition of plants and animals• volcanic eruptions.• However, people have caused the amount of CO2 in the

atmosphere to significantly increase by:• burning carbon containing fuels such as oil, coal, natural gas and

wood• clearing forests and draining peatlands. • Increases in CO2 in the atmosphere are likely to be responsible for

global warming which may cause climate change. There are no national guidelines.

Methane (CH4)

• Methane (CH4)• Methane (CH4) is a powerful greenhouse gas that has

20 times the warming potential of CO2. Also known as natural gas, methane is lighter than air and is odourless.

• In the region the main source of methane comes from the digestion system of livestock. Other sources include landfills, anaerobic decay and accidental emissions of natural gas (for example when filling gas bottles).

• There are no national guidelines. Find out more about emissions of methane from livestock farming in the Region

Nitrogen oxides (NOx)

• Oxides of nitrogen include nitrogen dioxide (NO2), nitric oxide (NO), and nitrous oxide (N2O). Depending on the type of nitrogen oxide, they contribute to ozone loss and greenhouse gases that are likely to be responsible for global warming which may cause climate change.

• Nitrogen dioxide can irritate the lungs and lower resistance to respiratory infections such as the flu. Nitrogen dioxide and nitric oxide also react with sunlight and VOCs to produce smog.

• Major sources of NOx are combustion in motor vehicle engines, gas appliances, and thermal power stations.

• Only NO2 has a national guideline: • 300 µg/m3 as a one hour average• 100 µg/m3 as a 24 hour average.• Find out about nitrogen dioxide as an indicator of air quality.

Sulphur oxides (SOx)

• Sulphur oxides are colourless gases that smell strongly at high levels. They are produced from the combustion of fossil fuels such as coal and oil during industrial processes and from geothermal eruptions.

• Only SO2 has a national guideline: • 500 µg/m3 as a 10 minute average• 350 µg/m3 as a one hour average• 125 µg/m3 as a 24 hour average• 50 µg/m3 as an annual average

Hydrogen sulphide (H2S)

• Hydrogen sulphide (H2S)• Hydrogen sulphide (H2S) is a colourless gas that smells

like rotten eggs. Apart from the unpleasant odour, H2S can irritate the eyes and respiratory system. High concentrations can kill people (high concentrations cannot be smelled because they paralyse the nerves we smell with).

Sources of hydrogen sulphide include geothermal areas and decaying sulphur-containing materials (for example in sewage ponds).

The national guideline is:• 7 µg/m3 as a 30 minutes average

Lead (Pb)• Lead (Pb)• Lead (Pb) is a poisonous metal that affects people’s nervous system, blood pressure

and immune system. Motor vehicle emissions used to be the main source of lead in the Waikato. In the mid 1980s steps were put in place to reduce and eventually remove lead from fuels. This has eliminated a major source of lead in the environment and lead is no longer of concern to air quality.

• Lead-based paint is still a source of lead poisoning. Although it’s not used for exterior house paint in New Zealand anymore, lead-based paint can still be found on some older houses (especially those built before the late 1970s).

• If your home has lead-based paint, you can reduce the risk of lead poisoning by:• Hiring a professional to remove the paint when redecorating.• Keeping surfaces as clean and dust-free as possible.• Washing your hands before eating.• Keeping children away from areas where paint is chipped or peeling. • The national guideline is:• 0.2 µg/m3 as a three month average

Volatile organic compounds (VOCs

• Volatile organic compounds (VOCs) include a large range of organic materials that create fumes, for example, benzene. Depending on the type, VOCs can affect human health, reduce visibility, and smell bad. Sources of VOCs include industry, vehicles and some types of vegetation.

• There are no national guidelines

Odour

• Odours are caused by mixtures of chemicals that stimulate the nerves we smell with. An unpleasant, strong, long-lasting odour can be a severe nuisance, reducing our enjoyment of life.

• Sources of odour could include pulp and paper manufacturers, rendering plants, waste water treatment plants and intensive indoor animal farms (for example piggeries and poultry farms).

• There are no national guidelines.

Agrichemicals

• Agrichemicals are chemicals (other than fertiliser) used in agriculture. They include fungicides, insecticides and herbicides. Agrichemical spray drift can affect human health and nearby crops that are not the target of spraying.

• There are no national guidelines. • Find out more about how Environment Waikato

manages agrichemical spray drift in our Proposed Regional Plan

Ozone (O3)

• Ozone (O3)• Although ozone in the upper atmosphere protects the

planet from damaging ultraviolet rays, at ground level it is an unwanted pollutant. Ozone can affect our health (by causing respiratory problems), and the environment as it is harmful to vegetation.

• The proposed Waikato Regional Plan Air Module sets the proposed regional guideline for ozone at:

• 150 µg/m3 for a one hour period • 100 µg/m3 for an eight hour period

Particulate matter

• Particulate matter• There are two types of particulate matter (small particles) in the air: • large deposited particles - for example dust • fine particles (PM10) - for example smoke particles from fires. • Deposited particles• Wind blown dust, volcanic eruptions, fires and pollen are sources of deposited

particles. Particles are generally larger than 20 microns across (about half the thickness of a human hair). They can cause health effects such as allergies, and settle on surfaces, making them dirty. There are no national guidelines.

• Fine particles (PM10) • The major sources of fine particles are home fires, motor vehicles and power stations.

Volcanic eruptions also produce PM10. Fine particles make the air hazy, reducing visibility. Smaller than 10 microns across, they are about a fifth the width of a human hair. PM10 can affect health when breathed in, especially for people with asthma or susceptible to respiratory illnesses. The national guideline is:

• 50 µg/m3 as a 24 hour average. • Environment proposed regional guideline is 50 µg/m3 as a 24 hour average. Find out

about fine particles (PM10) as an indicator of air quality.

Haze Occurrences

Haze, Mist or Fog ?

• Often, haze is confused with mist and fog. During the early morning or after rain showers when temperatures are low and humidity is high, mist and sometimes fog forms in valleys and lowlands, gradually clearing when the sun reappears. Mist and fog are formed as a result of the condensation of water vapour on particulates suspended in the atmosphere. Meteorologically, mist is defined as being present if diminished visibility occurs (with no other weather condition being present) and relative humidity of the atmosphere at the surface of the earth is above 95%. When the horizontal visibility falls below 1000 metres the phenomena is classified as fog

IS HAZE HARMFUL ?

• Haze originating from natural sources such as sea salt and soildust is generally harmless to humans. Slight, transient haze visible in most towns and cities has not been proven to cause any serious long-term health effects on the population. However, during a severe haze episode, prolonged exposure to high concentrations of particulates can be harmful to health. Associated with previous haze episodes, there have been reports of increases in incidences of eye and throat irritations and respiratory difficulties among sensitive groups. During a haze episode, the public are strongly urged to follow the advice issued by the local health authoritie

Global Level

• United Nation render help in form of money, technology transfer, man power to effected nations.

• ASEAN Countries cooperate in weather forecast and early disaster signal systems

Measure to handle of Haze Problem

Measure to handle of Haze ProblemNational Level

• Cloud seeding• API Index Monitoring• Furnishing information on local regulatory requirement Clean Air Regulation

to industries, government agency’s and public.• curfew(Natural Disaster ) –Prohibition of outdoor movement• Residential transfer from effected place • Enhancement of existing environmental laws with higher fine.• Improve the public transport efficiency• Encourage industries on usage of solar base generators.• Vehicle emmision control • Encourage usage of gas fuel replacing fossil fuels (Coal, diesel, bunker oil).• Encourage industries to install particulate electrostatic precipitor & cyclone

for industrial air emission.• Motor vehicle more than 15 years to be condemned.• Render incentive such as tax free and other incentive for industries uses

natural gas replacing diesel and coal.• Replace coal or diesel powered power plant with LNG.

Individual

• Stop smoking• Stop open burning of debris.• Reduce usage of motor vehicle (Car Pooling)• Utilize public transport • Cycling or walking habit for near destination.• Reduce electric wastage.• Install catalytic converter for motor vehicle• Use unleaded petrol• Plant vegetations as soil cover in house yards.• Report all open burning to State Environmental Department.• Water spraying on exposed soil surface.• Avoid out door movement with motor vehicle if unnessessary.• Replace fire wood with gas fuel for cooking.• Render donation for National Haze Fund and take active part in

social and voluntary team to render help in case of serious haze episode.

Measure to handle of Haze Problem

MitigationMitigation Measure

• Damping of exposed laid such as construction site• Installation of control device by industry and transportation devices.

They can either destroy contaminants or remove them from an exhaust stream before it is emitted to the atmosphere.

a) Electrostatic precipitators, cyclones, and fabric filters such as bag houses b) Carbon adsorption c) Condensers d) Selective catalytic reduction (SCR) and

non-selective catalytic reduction (NSCR), known as catalytic converters e) Exhaust gas recirculation f) Flue gas desulphurization and other gas scrubbers g) Flare stacks

Motor Vehicle Pollution

Defination:

Vehicle emissions• Vehicle emissions• Motor vehicles produce a range of contaminants that can pollute our

Region’s air, such as:• carbon monoxide • fine particles (smoke)• volatile organic compounds (VOCs) - partly burnt fuel• sulphur oxides• nitrogen oxides. • These contaminants affect the environment and human health. Find out how

we monitor carbon monoxide, nitrogen dioxide and fine particles in the Region.

• Vehicles are also an important source of carbon dioxide, a greenhouse gas associated with climate change.

• In Malaysia, air pollution from vehicles varies from suburb to suburb and is highest in central Hamilton. Vehicle emissions are highest when traffic density is greatest - between 10am and 4pm.

• Are petrol and diesel emissions different?• Petrol and diesel engines work in slightly different ways

and burn different fuels, so they produce different exhausts. Compared with petrol engines, diesel engines produce smaller amounts of unburnt and partially burnt fuel (hydrocarbons and carbon monoxide) but can produce more nitrogen oxides and large amounts of smoke (fine particulates). These particles consist of soot, hydrocarbons, sulphur-based chemicals and volatile organic compounds (VOCs).

• Heavy duty diesel vehicles, such as trucks, can be very polluting because they produce large amounts of particulates and nitrogen oxides. Diesel exhaust has also been shown to be a probable cause of cancer

Vehicle emissions

• What you can do• You can help reduce the amount of air contaminants

polluting our air by reducing the number of times you use a motor vehicle. You could try:

• carpooling• using public transport (trains, buses and shuttles)• cycling• walking. • Check out the Bus Timetables .• If you do need to use a private motor vehicle to get

around, make sure you drive smart and keep it in tune.

Vehicle emissions

• Keep in tune• Petrol vehicles• Maintain and tune your engine as recommended by the

manufacturer. Many faults can increase contaminants in the exhaust, for example:

• a rich idle mixture or incorrect air/fuel ratios• a dirty air filter• an incorrectly adjusted carburettor• defective spark plugs or worn distributor contacts• a faulty ignition coil• improper timing • vacuum leaks, burned valves, worn rings and head gasket leaks

Vehicle emissions

• Diesel vehicles• Too much diesel exhaust smoke can indicate engine problems.

Follow these tips to reduce smoke and keep your diesel vehicle well maintained:

• Clean or change your air filter regularly. • Change your engine oil at least as often as the manufacturer’s

recommendation. Dirty engine oil becomes thick. This causes excessive engine and turbocharger wear.

• Maintain your engine’s fuel injection system (as recommended by the manufacturer). This includes changing the fuel filter at recommended intervals, regularly draining the water/fuel separator, having injectors checked, cleaned or replaced and the fuel injection pump maintained as needed.

Vehicle emissions

Sources of common Heat Generations:1) Fossil-fuel power plant2) Cooling Tower3) Conventional Boiler &Heating unit4) Road Traffic Movement5) Nuclear Reactors6) Forest Fire & Agricultural burning.7) Others

Anthropogenic Heat Generation (AHG)

Anthropogenic Heat GenerationThe CO2 concentration in the atmosphere has been increasing since the mid 1800s. The increase correlates well with burning of fossil fuels. Thus, humans appear to have an effect

Effect AHG

1.Atmospheric temperature increase.

2.Low Dissolve oxygen in rivers.

3.Loss of species especially aquatic life.

4.UHI (urban heat Island)

5.Global warming

6. Immergence of new species.

Mitigation Measures

• Biomass fuel (control calorific value)

• Retention unit from cooling water before discharge.

• Encourage usage of public transport.

• Cooling mechanism for heat generating unit.

• Land Usage of the World

Cropland: Land used for temporary and permanent crops. Permanent crops include cocoa, coffee, fruit, rubber and vines crops. It does not include tree crops for timber and wood products.

Pasture: Permanent pasture includes lands used for five or more years for foraging, including wildland, grassland, natural and cultivated crops. Grasslands not used for pasture falls under the "other" category.

Forest: Land under natural forests or planted stands of trees. Also includes logged areas to be replanted in the near future, after logging.

Other: Uncultivated land, grasslands not used for pasture, developed areas, roads, wetlands and wastelands

Changes Of Landuse

Effects

1) Soil erosion

2) Landslide

3) Water Quality degradation

4) Desertification

5) Surface Albedo increase

6)

Mitigation Measures

LAND USE & NITROUS OXIDE

• Nitrous oxide releases showed a marked drop to very low values within days of clear cutting, but mean releases doubled over the following month to levels less than half those of undisturbed forest, i.e. Ievels similar to those from bare soil and regenerating clearcuts. In contrast, pastures released very little nitrous oxide. Nitrous oxide fluxes from undisturbed rain-forest soils were very variable, with some sites consistently high and others low. Nitrous oxide release was very low from grassland and pasture on clay soils, and from undisturbed forests on sandy soils. Agricultural and older secondary forest had high N2O release rates, comparable to primary forest on clay soils. These patterns appear to reflect plant-root distributions and competition for ammonium between nitrifying bacteria and soil mycorhizae (14). Little N2O was released from cattle manure, perhaps because of insufficient dietary nitrogen.  

Carbon Sequestration1) Afforestation, reforestation and restoration of degraded lands 2) Improved silvicultural techniques to increase growth rates 3) Implementation of agroforestry practices on agricultural lands

Carbon Conservation1) Conservation of biomass and soil carbon in existing forests 2) Improved harvesting practices (e.g. reduced impact logging) 3) Improved efficiency of wood processing 4) Fire protection and more effective use of burning in both forest and agricultural systems

Carbon Substitution1) Increased conversion of forest biomass into durable wood products for use in place of

energy-intensive materials 2) Increased use of biofuels (e.g. introduction of bioenergy plantations) 3) Enhanced utilization of harvesting waste as feedstock (e.g. sawdust) for biofuel

Source: Bass et al., 2000.

Terrestrial Carbon Management Strategies for Forest & Land use

Species LossAs humans establish cities, they disturb habitats and destroy others. But, at the same, time they import new species of plants and animals and create habitats for other unintended species.

a) Modification of Habitats  Modifications can take place in many ways. Natural ground cover is replaced with grasses and decorative plants, although many native species will be left in place. Fertilizers spread across lawns finds its way into water channels where it promotes the grow of plants at the expense of fish. Waste dumped into streams lowers oxygen levels during its decay and caused the die-off of plants and animals. Sometimes, cities allow native species, such as squirrels and raccoons, to increase far above their natural concentrations.

b) Destruction of Habitats  In some cases, entire habitats are eradicated by urbanization and native species are pushed out of cities.

c) Creation of New Habitats  New habitats are also created for some native and non-native species. Urbanization has, for example, eliminated many bat colonies in caves, but has provided sites such as bridges for these species to nest. Cities also create habitats for some species considered pests, such as pigeons, starlings, sparrows, rats, mice, flies and mosquitoes.

Causes

• Deforestation

• Urbanization

• Agricultural

• Land Mining

• Rapid population Growth (Residence)

• Recreation and others (hunting)

Mitigation Measures

• Reserved forest

• Animal conservation activities

• Strict Legislation on hunting

• Relocation of affection animal population

• Interbreeding by technological means

Agricultural Activities

• Definition:Agriculture (a term which encompasses farming) is the process of producing food, feed, fiber and other goods by the systematic raising of plants and animals.

• Farming sometimes refers to subsistence agriculture, the production of enough food to meet just the needs of the farmer/agriculturalist and his/her family.

• It may also refer to industrial agriculture, (often referred to as factory farming) long prevalent in developed nations and increasingly so elsewhere, which consists of obtaining financial income from the cultivation of land to yield produce, the commercial raising of animals (animal husbandry), or both

Agriculture Ratio• Top agricultural products,2004

individual crops (million metric tons) Sugar Cane 1,324Maize 721Wheat 627Rice 605Potatoes 328Sugar Beet 249Soybean 204Oil Palm Fruit 162Barley 154Tomato 120

Source:UN Food & Agriculture Organisation (FAO)[4]

Causes

• Pesticide /fungicide/ herbicide

• Soil erosion from structure (Irrigation/Road)

• Open burning (land opening)

Mitigations

1) Biodegradable or Natural pesticide/herbicide/fungicide eg. Bacillus Thugiansis /Paraquat

2)Prohibition of forest burning

3) Land closure vegetation

4) Air craft usage in fertilizing & pesticide

5) Soil conservation and nutrient management

Industrialization• Industrialization or an industrial revolution (in general, with lowercase letters) is a

process of social and economic change whereby a human society is transformed from a pre-industrial (an economy where the amount of capital accumulated is low) to an industrial state (see Pre-industrial society). This social and economic change is closely intertwined with technological innovation, particularly the development of large-scale energy production and metallurgy. Industrialisation is also related to some form of philosophical change, or to a different attitude in the perception of nature, though whether these philosophical changes are caused by industrialisation or vice-versa is subject to debate.

• Industrialisation has spawned its own health problems. Modern stressors include noise, air, water pollution, poor nutrition, dangerous machinery, impersonal work, isolation, poverty, homelessness, and substance abuse. Health problems in industrial nations are as much caused by economic, social, political, and cultural factors as by pathogens. Industrialisation has become a major medical issue world wide, and hopefully will become less of a problem over the upcoming years.

• When capitalised, Industrial Revolution refers to the first industrial revolution, which took place in Britain during the 18th and 19th centuries. The Second Industrial Revolution describes later, somewhat less dramatic changes which came about with the widespread availability of electric power, the internal-combustion engine and assembly lines

Causes

• UHI(urban Heat Island)

• Air Polution- asthma, respiratory allergence

• water pollution- Reduce good water sources

Mitigations

1) Zoning of industries2) Green area requirement3) Product free of CFC & Toxic Chemical4) Product Compliance RoSH (Restriction of

Hazardous Substance) e.g.. Cd, Hg, As.5) Recycling facility for useful material.6) Waste water & air Pollutant compliance to

EQA (SIE 1979) standard B and ambient air Quality standard.

Ozone Layer Depletion

• Ozone in the stratosphere is formed by a natural photochemical process when ultraviolet radiation from the sun splits molecules of oxygen into the individual oxygen atoms from which they are formed. The free O atoms soon react with O2 molecules to form O3.

• This process works both ways: O3 molecules that are unlucky enough to be struck by UV radiation are split back to an O2 molecule and a free O atom. The free O atom can merge with an O2 molecule to once again form an O3 molecule

• Generation O3 <Destruction O3 – cause O3 Depletion (Stratosphere)

Ozone Depletion

Ozone

• What Is Ozone And How Is It Formed? • Ozone (O3 : 3 oxygen atoms) occurs naturally in the

atmosphere. • The earth's atmosphere is composed of several layers.

We live in the "Troposphere" where most of the weather occurs; such as rain, snow and clouds. Above the troposphere is the "Stratosphere"; an important region in which effects such as the Ozone Hole and Global Warming originate. Supersonic jet airliners such as Concorde fly in the lower stratosphere whereas subsonic commercial airliners are usually in the troposphere. The narrow region between these two parts of the atmosphere is called the "Tropopause".

Ozone Location at Stratosphere

Ozone Dynamics*• It's ironic that at ground level, ozone is a health hazard -

it is a major constituent of photochemical smog. However, in the stratosphere we could not survive without it. Up in the stratosphere it absorbs some of the potentially harmful ultra-violet (UV) radiation from the sun (at wavelengths between 240 and 320 nm) which can cause skin cancer and damage vegetation, among other things.

• Although the UV radiation splits the ozone molecule, ozone can reform through the following reactions resulting in no net loss of ozone:

O3 + hv -> O2 + O -------(3)O + O2 -> O3--------------(2) as above

Ozone is also destroyed by the following reaction: O + O3-> O2 + O2------- (4)

Catalytic Destruction of Ozone • Measurements taken of the chemical species above the pole show the high levels of active forms of

chlorine that we have explained above. However, we still have many more atoms of ozone than we do of the active chlorine so how it is possible to destroy nearly all of the ozone?

• The answer to this question lies in what are known as 'catalytic cycles'. A catalytic cycle is one in which a molecule significantly changes or enables a reaction cycle without being altered by the cycle itself.

• The production of active chlorine requires sunlight, and sunlight drives the following catalytic cycles thought to be the main cycles involving chlorine and bromine, responsible for destroying the ozone:

(I) 2 x (Cl + O3)----------------->2 x (ClO + O2)  

ClO + ClO + M----->Cl2O2 + M

Cl2O2 + hv------>Cl + ClO2    ClO2 + M------------>Cl + O2 + M 

then:net:2 O3------------->3 O2 and 

(II) ClO + BrO---------------->Br + Cl + O2  

Cl + O3---------------->ClO + O2  Br + O3----------------->BrO + O2   

net:2 O3---------------->3 O2

On average, the size of the ozone hole is larger than many countries.

Source:  Geocities.com, 1998

How do CFCs depleting ozone?

• A relatively recent concern is the depletion of ozone, O3 due to the presence of chlorine in the troposphere, and eventually their migration to the stratosphere. A major source of chlorine is Freons: CFCl3 (Freon 11), CF2Cl2 (Freon 12), C2F3Cl3 (Freon 113), C2F4Cl2 (Freon 114). Freons decompose in the troposphere. For example,

• CFCl3 ® CFCl2 + ClCF2Cl3 ® CF2Cl + Cl.

• The chlorine atoms catalyze the decomposition of ozone, • Cl + O3 ® ClO + O2 • and ClO molecules further react with O generated due to photochemical

decomposition of ozone: • O3 + h v ® O + O2,

ClO + O ® Cl + O2O + O3 ® O2 + O2.The net result or reaction is2 O3 ® 3 O2

• Thus, the use of CFCs is now a world wide concern. In 1987, one hundred and forty nine (149) nations signed the Montreal Protocol. They agreed to reduce the manufacturing of CFCs by half in 1998. They also agree to phase out CFCs

Relative contribution of each compound to caused ozone depletion

(UNEPdata, 1990)

Atmosphere Wavelength Absorbent

• Stratospheric Oxygen and Ozone molecules absorb 97-99% of the sun's high frequency Ultraviolet light, light with wavelengths between 150 and 300nm. Ultraviolet-B(UV-B) is a section of the UV spectrum, with wavelengths between 270 and 320nm

UV Radiation • SUN ELEVATION • The higher• the UV radiation level.Thus UV radiation• levels vary with time of day and time of• year. Outside the tropics, the highest• levels occur when the sun is at its• maximum elevation, at around midday• (solar noon) during the summer months.• LATITUDE• The closer to equatorial regions, the• higher the UV radiation levels.• CLOUD COVER• UV radiation levels are highest under• cloudless skies but even with cloud cover,• UV radiation levels can be high.• Scattering can have the same effect as• the reflectance by different surfaces and• thus increase total UV radiation levels

ALTITUDEAt higher altitudes, a thinneratmosphere absorbs less UV radiation.With every 1000 metres increase inaltitude, UV radiation levels increase by10% to 12%.OZONEOzone absorbs some of the UV radiationthat would otherwise reach the Earth’ssurface. Ozone levels vary over the yearand even across the day.GROUND REFLECTIONUV radiation is reflected or scattered tovarying extents by different surfaces, e.g.fresh snow can reflect as much as 80% ofUV radiation, dry beach sand about 15%and sea foam about 25%.

UV Radiation

UVI• The Global Solar UVI is formulated using the International

Commission on Illumination (CIE)reference action spectrum for UV-induced erythema on the human skin (ISO 17166:1999/CIES 007/E-1998).

• It is a measure of the UV radiation that is relevant to and defined for a horizontal surface.The UVI is a unitless quantity defined by the formula:

• where Eλ is the solar spectral irradiance expressed in W·/(m2·nm1) at wavelengthλ and dλ is the wavelength interval used in the summation. Ser (λ) is the erythema referenceaction spectrum, and ker is a constant equal to 40 m2/W.

UVI (Ultra Violet Index)

UV Index Vs Time

Bereau of Meteorology , Australia 2002

Health Effect To Human

Basel cell carsinoma Squamous cell carsinoma Maligant Melanoma

1 Ultraviolet radiation. An authoritative scientific review of environmental and health effects of UV, with reference to global ozone

layer depletion. Geneva,World Health Organization, 1994 (Environmental Health Criteria Monograph, No. 160).

2 Proceedings of an international workshop on ultraviolet radiation exposure, measurement and protection, St Catherine’s

College, Oxford, 1999. Radiation Protection Dosimetry, 2000, 91:1-3.

REFERANCE

mitigation

• Montreal Protocol-The Montreal Protocol on Substances That Deplete the Ozone Layer is an international treaty designed to protect the ozone layer by phasing out the production of a number of substances believed to be responsible for ozone depletion. The treaty was opened for signature on September 16, 1987 and entered into force on January 1, 1989. Since then, it has undergone five revisions, in 1990 (London), 1992 (Copenhagen), 1995 (Vienna), 1997 (Montreal), and 1999 (Beijing).

There is a slower phase-out (to zero by 2010) of other substances (halon 1211, 1301, 2402; CFCs 13, 111, 112, etc) and some chemicals get individual attention (Carbon tetrachloride; 1,1,1-trichloroethane). The phasing-out of the less active HCFCs started only in 1996 and will go on till a complete phasing-out is achieved in 2030.There are a few exceptions for "essential uses", where no acceptable substitutes have been found (for example, in the metered dose inhalers commonly used to treat asthma and other respiratory problems).The substances in Group I of Annex A are:CFCl3 (CFC-11) CF2Cl2 (CFC-12) C2F3Cl3 (CFC-113) C2F4Cl2(CFC-114) C2F5Cl (CFC-115)

Mitigation

1,1,1,2-Tetrafluoroethane, also called simply tetrafluoroethane, R-134a or HFC-134a, is a refrigerant without an ozone depletion potential and thermodynamic properties similar to R-12 (dichlorodifluoromethane). It has the formula CH2FCF3, and a boiling point of −26.6 °C (−15.9 °F).

-26.08°C (247.07 K)Boiling point

-103.3°C (169.85 K)Melting point

Insoluble.Solubility in water

0.00425 g/cm³, gas.Density and phase

Properties

[811-97-2] [1]CAS number

Colorless gas.Appearance

102.03 g/molMolar mass

FC(F)(F)C(F)SMILES

C2H2F4Molecular formula

Suva 134aHFC-134aR-134a

Other names

1,1,1,2-tetrafluoroethaneSystematic name

General

1,1,1,2-Tetrafluoroethane

• Deforestation is the permanent destruction of indigenous forests and woodlands. The term does not include the removal of industrial forests such as plantations of gums or pines.

• Deforestation has resulted in the reduction of indigenous forests to four-fifths of their pre-agricultural area.

• Indigenous forests now cover 21% of the earth's land surface

Deforestation

• WHAT ARE FORESTS AND WOODLANDS?In a forest the crowns of individual trees touch to form a single canopy. In a woodland, trees grow far apart, so that the canopy is open.

• RATE OF DEFORESTATIONOf great concern is the rate at which deforestation is occurring. Currently, 12 million hectares of forests are cleared annually. Almost all of this deforestation occurs in the moist forests and open woodlands of the tropics. At this rate all moist tropical forest could be lost by the year 2050, except for isolated areas in Amazonia, the Zaire basin, as well as a few protected areas within reserves and parks. Some countries such as Ivory Coast, Nigeria, Costa Rica, and Sri Lanka are likely to lose all their tropical forests by the year 2010 if no conservation steps are taken.

Deforestation

What causes DeforestationDeforestation is brought about by the following:

* conversion of forests and woodlands to agricultural land to feed growing numbers of people;

* development of cash crops and cattle ranching, both of which earn money for tropical countries;

* commercial logging (which supplies the world market with woods such as meranti, teak, mahogany and ebony) destroys trees as well as opening up forests for agriculture;

* felling of trees for firewood and building material; the heavy lopping of foliage for fodder; and heavy browsing of saplings by domestic animals like goats.

*To compound the problem, the poor soils of the humid tropics do not support agriculture for long. Thus people are often forced to move on and clear more forests in order to maintain production.

CONSEQUENCES OF DEFORESTATION

i)) Alteration of local and global climates through disruption of:• a) The carbon cycle. Forests act as a major carbon store because carbon dioxide

(CO2) is taken up from the atmosphere and used to produce the carbohydrates, fats, and proteins that make up the tree. When forests are cleared, and the trees are either burnt or rot, this carbon is released as CO2. This leads to an increase in the atmospheric CO2 concentration. CO2 is the major contributor to the greenhouse effect. It is estimated that deforestation contributes one-third of all CO2 releases caused by people.

• b) The water cycle. Trees draw ground water up through their roots and release it into the atmosphere (transpiration). In Amazonia over half of all the water circulating through the region's ecosystem remains within the plants. With removal of part of the forest, the region cannot hold as much water. The effect of this could be a drier climate.

• ii) Soil erosion With the loss of a protective cover of vegetation more soil is lost.• Iii) Silting of water courses, lakes and dams This occurs as a result of soil erosion. • iv) Extinction of species which depend on the forest for survival. Forests contain

more than half of all species on our planet - as the habitat of these species is destroyed, so the number of species declines (see Enviro Facts "Biodiversity").

• v) Desertification The causes of desertification are complex, but deforestation is one of the contributing factors (see Enviro Facts "Desertification")

Mitigation Measures• A) Reduced Impact Logging (RIL)

Traditional logging can result in very high damage to the residual tree stand, thus reducing the growth, biodiversity and carbon sequestration potential of the residual forest. If damage is reduced during logging, the residual forest will grow much faster and carbon sequestration more effective, while also enhancing the biodiversity of the residual stand. The New England Electric System (NEES) initiated a pilot project on RIL in Sabah in 1995, where almost 50% of logging damage was reduced during logging in this project operation. More or less 40 tonnes of carbon per hectare at a cost of $7.60 / tonne was saved 2 years after logging. Nearly 58,000 tonnes of carbon was saved over the 1,400 ha area. It was all achieved by the Reduced Impact Logging system, which involves greater control of logging roads, skidding tracks and directional felling. Apart from providing attractive carbon offset option, the system

• provides other benefits such as retaining biodiversity values, minimising fire risks and maintaining topsoil integrity. The system also ensures better-stocked forest stands, less damage, faster growing and greater volume yield of forest products.

Mitigation

B) Plantation Forest

Plantation forestry has become increasingly popular as a means of producing wood fibre for specific purposes, such as for a pulp and paper mill. In view of the increasing global demand of wood and wood fibre, the establishment of forest plantations seems to provide the only option as plantations as they are much more productive than natural forests and allow economic management on a sustainable manner.

• Natural Forest

• In former times, natural forests were extensive. However, much of the global tropical forests have

• been depleted or degraded due to conversion and harvesting of timber. Malaysia still has 62% of its land

• area as natural forest, most of it being in the hills. However, much of this area has been logged. Land use

• policies which promoted the conversion of forest land to other crops, notably rubber and oil palm, had

• resulted in heavy loss of forest areas in the past. However, these policies have not stopped, and a

• Permanent Forest Estate has been established in perpetuity. Natural forest management has been

• implemented in much of the natural forest where silvicultural practices have been implemented. These

• silvicultural practices comprise climber cutting and/or enrichment planting. Specific economic concerns

• can still lead to further losses of natural forests at localised locations. There is a debate whether to

• continue natural forest management or to establish forest plantations to meet future timber needs. Based

• upon projections on future timber needs, extensive plantations seem inevitable. Brazil, the country with

• largest natural forest in the world has programmes for plantations. Papua New Guinea, which has more

• than 70% of its land as natural forest, is establishing plantations (Appanah 1994).

Desertification• This degradation of formerly

productive land-- desertification--is a complex process. It involves multiple causes, and it proceeds at varying rates in different climates. Desertification may intensify a general climatic trend toward greater aridity, or it may initiate a change in local climate.

• Desertification does not occur in linear, easily mappable patterns. Deserts advance erratically, forming patches on their borders. Areas far from natural deserts can degrade quickly to barren soil, rock, or sand through poor land management. The presence of a nearby desert has no direct relationship to desertification. Unfortunately, an area undergoing desertification is brought to public attention only after the process is well underway. Often little or no data are available to indicate the previous state of the ecosystem or the rate of degradation. Scientists still question whether desertification, as a process of global change, is permanent or how and when it can be halted or reversed

Desert Formation• Desertification became well known

in the 1930's, when parts of the Great Plains in the United States turned into the "Dust Bowl" as a result of drought and poor practices in farming, although the term itself was not used until almost 1950. During the dust bowl period, millions of people were forced to abandon their farms and livelihoods. Greatly improved methods of agriculture and land and water management in the Great Plains have prevented that disaster from recurring, but desertification presently affects millions of people in almost every continent

Causes of Desertification

• Nomads moving to less arid areas disrupt the local ecosystem and increase the rate of erosion of the land.

• Increased population and livestock pressure on marginal lands .By pounding the soil with their hooves, livestock compact the substrate, increase the proportion of fine material, and reduce the percolation rate of the soil, thus encouraging erosion by wind and water.

• Grazing and the collection of firewood reduces or eliminates plants that help to bind the soil.

Mitigation Measures

• Placement of straw grids, each up to a square meter in area, will also decrease the surface wind velocity.

• Oases and farmlands in windy regions can be protected by planting tree fences or grass belts or wall.

• Sought to find and tap groundwater resources and to develop more effective ways of irrigating arid and semiarid lands

• Proper crop rotation to protect the fragile soil, on understanding how sand-fixing plants can be adapted to local environments,

• Proper grazing lands and water resources management to prevent effectively without being overused.

GREEN HOUSE EFFECT/ GLOBAL WARMING

GREEN HOUSE EFFECT/GLOBAL WARMING

Definition• The greenhouse effect, first discovered by Joseph Fourier in 1824,

and first investigated quantitatively by Svante Arrhenius in 1896, is the process by which an atmosphere warms a planet.

• Greenhouse effect may be used to refer either to the natural greenhouse effect, which is the greenhouse effect which occurs naturally on Earth, or to the enhanced (anthropogenic) greenhouse effect, which results from gases emitted as a result of human activities

• The difference between the greenhouse effect and global warming is that- global warming is anthropogenic where as the natural greenhouse effect is not take into consideration.

Natural Green House Effect

• The earth receives an enormous amount of solar radiation. The solar power flux density averages about 1366 watts per square meter, or 1.740×1017 W over the entire Earth.

• This figure greatly exceeds the power generated by human activities.

• The solar power hitting Earth is balanced over time by an equal amount of power radiating from the Earth (as the amount of energy from the Sun that is stored is small).

• Almost all radiation leaving the Earth takes two forms: reflected solar radiation and thermal black body radiation.

• Reflected solar radiation accounts for 30% of the Earth's total radiation- 6% of the reflected by the atmosphere, -20% is reflected by clouds,

- 4% is reflected by the surface.

Natural Green House Effect• The remaining 70% of the incoming solar radiation is absorbed

• This absorbed energy heats the atmosphere, oceans, and land and powers life on the planet.

• Like the Sun, the Earth is a thermal radiator. Because the Earth's surface is much cooler than the Sun (287 K vs. 5780 K), Wien's displacement law dictates that Earth radiates its thermal energy at longer wavelengths than the Sun. While the Sun's radiation peaks at a visible wavelength of 500 nanometres, Earth's radiation peak is in the longwave (far) infrared at about 10 micrometers.

16% by the atmosphere ( almost complete absorption of shortwave ultraviolet over most areas by the stratospheric ozone layer)

3% clouds; and

51% land and oceans.

70% Total absorbed

• The Earth's atmosphere is largely transparent at visible and near-infrared wavelengths, but not at 10 micrometers.

• The atmosphere itself behaves as a radiator in the far infrared, so it re-radiates this energy.

• The Earth's atmosphere and clouds therefore account for 91.4% of its longwave infrared radiation and 64% of Earth's total emissions at all wavelengths.

• Because the atmosphere is such a good absorber of longwave infrared, it effectively forms a one-way blanket over Earth's surface. Visible and near-visible radiation from the Sun easily gets through, but thermal radiation from the surface can't easily get back out. In response, Earth's surface warms up.

• surface is heated by two sources: direct solar radiation, and thermal radiation from the atmosphere; it is thus warmer than if heated by solar radiation alone.

Natural Green House Effect

NATURAL GREEN HOUSE EFFECT

SUMMARY• The Earth receives energy from the Sun in the form of

radiation, mostly at visible wavelengths. To the extent that the Earth is in a steady state, the energy stored in the atmosphere and ocean does not change in time, so energy equal to the incident solar radiation must be radiated back to space. Radiation leaving the Earth takes two forms: reflected solar radiation and thermal, or infrared radiation. The Earth reflects about 30% of the incident solar flux; the remaining 70% is absorbed, warms the land, atmosphere and oceans, and powers life on this planet. Eventually this energy is reradiated to space as infrared photons. This thermal, infrared radiation increases with increasing temperature..

• Water vapour (H2O) causes about 60% of Earth's naturally-occurring greenhouse effect.

• Other Green Houses gases influencing the effect include:- carbon dioxide (CO2) (about 26%), -methane (CH4), -nitrous oxide (N2O) 8 % collectively-ozone (O3)

• The wavelengths of light that a gas absorbs can be modelled with

quantum mechanics based on molecular properties of the different gas molecules. It so happens that heteronuclear diatomic molecules and tri- (and more) atomic gases absorb at infrared wavelengths but homonuclear diatomic molecules do not absorb infrared light. This is why H2O and CO2 are greenhouse gases but the major atmospheric constituents (N2 and O2) are not.

Green House Gases

Atmospheric absorption of Radiation

What Causes Global Warming

• It is useful to define the radiative forcing corresponding to any change in the state of the system: the radiative forcing is the change in the radiation balance at the top of the atmosphere which would result from a given change in the climate system, assuming that all other components of the system are unaffected. It is defined in such a way that positive forcing corresponds to heating (more incoming than outgoing radiation).

• useful example is that of carbon dioxide. If we took pre-industrial carbon dioxide levels and increased them to current levels without changing any other aspect of the climate system, then there would be an imbalance in the climatological radiation budget. The incoming radiation would be unaffected, but the outgoing longwave would be absorbed more strongly (the enhanced greenhouse effect), so the longwave cooling (OLR) to space would be reduced and a net heating would occur: this is a positive radiative forcing, and can be computed with some accuracy. In the case of carbon dioxide, it is reckoned to be around 1.5 Wm-2.

What Causes Global Warming

Fig. 4.1 The radiative forcing due to various atmospheric constituents, adapted from Houghton (1997). The error bars indicate the degree of uncertainty. Some further information on these gases and aerosols is given here. Look also in Graedel and Crutzen.

CO2 Concentration in 1995

Figure a & b : Recent measurements of atmospheric carbon dioxide concentrations and Major Greenhouse Gases

CONSEQUENSE• The warming of the Earth in the 20th century is thought to have

been accompanied by an imbalance of roughly 0.5 W/m2 averaged over the Earth's surface, most of this heat being stored in the oceans, a number that should be compared to 240 W/m2, the estimated average rate of solar energy absorption by the Earth and emission of infrared radiation by the Earth to space.)

• greenhouse gases (GHG) input into the atmosphere, will cause atmosphere temperature increase at a rate of about 0.3oC per decade.

• This will lead to average temperatures about 1 degree warmer by the year 2025 and about 3 degrees warmer by the year 2100. 

Effects of Global warming 

1) Global Precipitation changes - A warmer atmosphere will lead to increased evaporation from surface waters and result in higher amounts of precipitation. The equatorial regions will be wetter than present, while the interior portions of continents will become warmer and drier than present.

2) Changes in vegetation patterns - because rainfall will distributed differently, vegetation will have to adjust to the new conditions. Mid latitude regions are likely to be more drought prone, while higher latitude regions will be somewhat wetter and warmer than normal, resulting in a shift in agricultural patterns.

3) Increased storminess - A warmer, wetter atmosphere will favor tropical storm development. Hurricanes will be stronger and more frequent.

4) Changes in Ice patterns. - Due to higher temperatures, ice in mountain glaciers will melt. But, because more water will be evaporated from the oceans, more precipitation will reach the polar ice sheets causing them to grow.

5) Reduction of sea ice - Sea ice will be greatly reduced to the increased temperatures at the high latitudes, particularly in the northern hemisphere where there is more abundant sea ice. Ice has a high albedo (reflectivity), and thus reduction of ice will reduce the albedo of the Earth and less solar radiation will be reflected back into space, thus enhancing the warming effect.

6) Thawing of frozen ground - Currently much of the ground at high latitudes remains frozen all year. Increased temperatures will cause much of this ground to thaw. Organic compounds and gas hydrates in the frozen ground will be subject to decay, releasing more methane into the atmosphere and enhancing the greenhouse effect. Ecosystems and human structures currently built on frozen ground will have to adjust.

Effects of Global warming 

Effects of Global warming 6) Rise of sea level - Warming the oceans results in expansion of water and thus

increases the volume of water in the oceans. Along with melting of mountain glaciers and reduction in sea ice, this will cause sea level to rise and flood coastal zones, where much of the world's population currently resides.

7) Changes in the hydrologic cycle - With new patterns of precipitation changes in stream flow and groundwater level will be expected.

8) Decomposition of organic matter in soil - With increasing temperatures of the atmosphere the rate of decay of organic material in soils will be greatly accelerated. This will result in release of CO2 and methane into the atmosphere and enhance the greenhouse effect. 

9) Breakdown of gas hydrates - This is basically solid water with gas molecules like methane locked into the crystal structure.  They occur in oceanic sediments and beneath frozen ground at the high latitudes.  Warming of the oceans or warming of the soil at high latitudes could cause melting of the gas hydrates which would release methane into the atmosphere.  Since methane is a greenhouse gas, this would cause further global warming.

Earth Temperature Prediction 2041

Fig. 14.5. Hadley Centre prediction, from an ensemble of four climate model runs, of the changes in annual mean temperature, relative to the 1961-90 mean, for the period 2041-70.

• Possible sea level change is one of the greatest threats of climate change. Measuring sea levels consistently is difficult (e.g. problems associated with land-mass elevation changes), but best estimates are that the globally-averaged sea level has risen by 10-25cm over the last 100 years. There are several factor influencing sea levels:

• Thermal expansion. The density of seawater falls as its temperature rises. It is estimated that this effect has contributed 2-7cm of the observed sea level rise over the last century.

• Glaciers and icecaps. Water is stored as ice over land-masses: the rate of change of this storage is a balance between accumulation (e.g. snowfall) and loss (e.g. melting, iceberg calving). In many remote areas, this is difficult to measure, but there seems to have been a general thinning of glaciers over many parts of the world, implying a contribution to sea level rise.

• The Greenland and Antarctic ice sheets. These areas contain the bulk of non-oceanic water on Earth. Their responses to temperature rises are not obvious: climate model results suggest that a 1oC rise in global temperature would result in a loss of ice from Greenland, giving around 0.3 mm year-1 sea level rise while Antarctica would gain ice (increased atmospheric humidity giving increased precipitation over the ice sheets), resulting in something like -0.3 mm year-1 sea level decrease. There remain significant doubts about these estimates.Observations of temperature around the Antarctic Peninsula suggest that there has been a significant warming in this area, of around 2oC since 1940. It is thought that this has been responsible for the observed break-up of the Larsen Ice Shelf. More information on Antarctic climate change can be found at the British Antarctic Survey web site.

• Another concern, relating to the West Antarctic ice sheet, is that, as much of it is grounded below sea level, it may at some stage break free and melt over a relatively short timescale, with the potential to increase sea levels by around 5m. At present there is insufficient understanding of ice dynamics to make any clear statement about the likelihood of such an event.

Sea Level Changes

Recent Sea Level Rise

Sea Level Changes• Surface and ground water. There are many components to the

land-based hydrological cycle which may contribute to sea levels, and few are well-quantified. Examples are: ground water depletion (sea level rise); surface water reservoir growth (fall); deforestation (uncertain); loss of wetlands (rise) and permafrost melting (rise).

• It is important to be clear that one factor which does not contribute to sea level rise is the melting of sea ice: the ice displaces its own mass of water (Archimedes' principle) and, on melting, will not change the water volume. Computations of sea level changes over the last century using the components detailed above, give estimates of -19 to 37 cm. This is thought to represent a reasonable level of understanding of the observed changes (although the negative lower limit on the calculated value must be a cause for concern). The biggest level of uncertainty in these computations is thought to be in the polar ice sheet budgets

Global Warming 2080An important consequence of global warming would be sea-level rise. This has two separate causes: 1 )Melting of the Antarctic and Greenland ice sheets. 2) Thermal expansion of the oceans.

Current estimates for sea-level change predict a rise of about 45 cm by 2080. The most serious effect of this would be coastal flooding, with consequent displacement of populations and loss of wetland habitats. Fig. 14.7 shows Hadley Centre predictions of the areas most at risk from coastal flooding, assuming the IPCC IS92a emission scenario. Because the time-scales for warming of the deep oceans are very long, the thermal expansion contribution to sea-level rise is expected to continue for several centuries even if warming of the atmosphere ceases.  

Fig. 14.7. Hadley Centre prediction of the effects of sea-level rise by 2080.

Mitigation1) -The Kyoto Protocol is an agreement made under the United Nations Framework

Convention on Climate Change (UNFCCC). Countries that ratify this protocol commit to reduce their emissions of carbon dioxide and five other greenhouse gases, or engage in emissions trading if they maintain or increase emissions of these gases.

-The Kyoto Protocol now covers more than 160 countries globally and over 55% of global greenhouse gas (GHG) emissions.

2) Enforcement Halon & refrigerant prohibition MALAYSIA Laws. a) Environmental Quality Act 1974, *Environmental Quality Regulation (Refrigerant Management) 1999. *Environmental Quality Regulation (Halon Management) 1999.

b) Environmental Quality Regulation (Open Burning)

Kyoto Protocol Principle• Kyoto is underwritten by governments and is governed by global legislation enacted under the

UN’s aegis • Governments are separated into two general categories: developed countries, referred to as

Annex 1 countries (who have accepted GHG emission reduction obligations); and developing countries, referred to as Non-Annex 1 countries (who have no GHG emission reduction obligations)

• Any Annex 1 country that fails to meet its Kyoto target will be penalised by having its reduction targets decreased by 30% in the next period.

• By 2008-2012, Annex 1 countries have to reduce their GHG emissions by around 5% below their 1990 levels (for many countries, such as the EU member states, this corresponds to some 15% below their expected GHG emissions in 2008). Reduction targets expire in 2013.

• Kyoto includes "flexible mechanisms" which allow Annex 1 economies to meet their GHG targets by purchasing GHG emission reductions from elsewhere. These can be bought either from financial exchanges (such as the new EU Emissions Trading Scheme) or from projects which reduce emissions in non-Annex 1 economies under the Clean Development Mechanism (CDM), or in other Annex-1 countries under the JI.

• Only CDM Executive Board-accredited Certified Emission Reductions (CER) can be bought and sold in this manner. Under the aegis of the UN, Kyoto established this Bonn-based Clean Development Mechanism Executive Board to assess and approve projects (“CDM Projects”) in Non-Annex 1 economies prior to awarding CERs. (A similar scheme called “Joint Implementation” or “JI” applies in transitional economies mainly covering the former Soviet Union and Eastern Europe).

• What this means in practice is that Non-Annex 1 economies have no GHG emmision restrictions, but when a GHG emission reduction project (a “GHG Project”) is implemented in these countries, that GHG Project will receive Carbon Credits which can be sold to Annex 1 buyers.