GLOBAL WARMING

1. GLOBAL WARMING AND OZONE
DEPLETION
CH: 10

8. • HW
– What is Green House Effect? How does it sustain life
on the Earth?
– What is Global Warming? What are the causes of
GW?

9. • EXTREME WEATHER
– Recent Times, increasing number of news reports,
worldwide
• What could have caused the changes to the Earth?
• How would an increase in such extreme weather events
affect people & the environment?

10. SUMMARY
• Causes of GW
– Natural & man-made(GW)
• Extent of GW
– Increase in global temp.
(0.50)
• Consequences of GW
– Changes in Weather
pattern
– Impact on plants, animals,
people, sea level
• Measures
– International
– National
– individual
• Causes of O3 depletion
– Release of CFCs
• Extent of O3 depletion
– Thinning of 03 layer
• Consequences
– Impact on animals, plants,
people
• Measures
– International
– National
– Individual

11. • CHANGES IN EARTH’S CLIMATE
– Late 19th cent,
• Significant changes in climate
– Global temp rising
– Many reports of droughts, floods & storms
– 1985, scientists—a hole in ozone layer above Antartica
– Due to human activities
– In this ch.: two env challenges
» GW & O3 depletion
» & how to manage them

12. • THE GREEN HOUSE EFFECT
– Atmosphere
• Consists of gases
• Sun’s rays pass thru atm. & reflected by E’s surface.
• Heat trapped, E’s surface, warming up in lower atm.
• Gases are essential to stop heat loss to outer space
• Gases, which trap heat from sun’s rays—GHG
– Water vapour— evaporation/transpiration
– CO2 – respiration
– CH4 –released by bacteria in swampy areas etc.
– NO--
– CFCs
• The warming process is called GHE
– As atm is like greenhouse(used to maintain warm temp for plants to
grow)
– GHE is natural process
• E’s avg temp 150C
– Without GHG, E’s avg temp be 330C lower (too cold)

17. • GLOBAL WARMING
– CAUSES OF GW
• Amt of GHG in atm, doubled over last two centuries
– >industrial & other human activities worldwide.
– These GHG, do not break down easily, accumulate in atm.
– Causes more heat from Sun, trapped in lower atm.
– Called “Enhanced Green House Effect”
– Result is an increase in air temp worldwide, known as GW
– Fig. 10.3
• GHGs
– CO2
» Amt increased due to burning of FF
– NO
» Vehicle exhaust pipes
» Release when N based fertilisers break down.
– CH4
» Produced by bacteria in wet rice fields
» By decomposition of waste in landfills.
» In farms where cattle are reared, when cows belch.
– CFCs
» By aerosol sprays, foam packaging & solvents in industries.
» Through coolants in refrigerators, Acs & machinery in factories.

18. – EXTENT OF GW
• Last 100 yrs, 0.50C rise
• Temp increase more at poles than equator
• Disturbance in Albido, snow melt—more heat absorbed—oceans at
poles
– CONSEQUENCES OF GW
• CHANGES IN WEATHER CONDITIONS
– By 2100, >1.5 to 4.5 0C
– Faster evaporation from water bodies
– In dry regions, excessive evaporation
» Dry climate, more drier
» Severe droughts, heat waves
– In wetter regions,
» More rainfall,
» floods
• IMPACT ON PLANTS
– Vegetation growth will be affected
– As diff climate conditions, for diff plants are required
– Production of food crops decrease, food shortage
– In some places, as Alaska,
» Warmer climate, new crops can be grown.

19. • IMPACT ON ANIMALS
– Rise of global temp
» Impact on natural habitats.
» Yaks, llamas (low temp), migration to high altitudes
» Risk of extinction
• IMPACTS ON PEOPLE
– Negative impact on health
» Spread of diseases,
• Mosquitoes multiply rapidly in high temp.
• Dengue, malaria, yellow fever
» No of hot days will increase
• Dehydration, heat stroke
• RISING SEA LEVEL
– Ice caps at North & South Poles, melt
– Sea level rise, 20-50 cm by 2050
– Major coastal cities & low lying islands at risk.

20. • Projected threats due to sea level rise:
– Tribal pop/indegenous pop in small islands at risk
• Ex Cook island
– Increased erosion of coast, damage to
infrastructure, buildings.
• Ex Venice
– Arable farmland, destroyed near coastland,
migration to highland.
• Ex Carteret Islands of Papua New Guinea facing threat.
– Natural habitats & marine ecosystems, coastal areas
• Ex Polynesia at risk
– River deltas at threat
• Fertile land areas at lower course of rivers at risk.

22. • O3 DEPLETION
• Discovered a hole in ozone layer in 1985, studies in Antarctica
• Hole kept growing, 1987, big, size of USA
• Ozone layerO3 gas15-30 kmshieldUV rays
• Gradual destructionOzone depletion
– CAUSES OF O3 DEPLETION
• CFCs
– Chlorine
• Ozone layer, capable of replacing itself
– CFC high amt atmosphere faster depletion(ozone)than
recovery
• Sources of CFCs
– Industrial Cleaning Agents (22%)
– Insulation and foam packaging (30%)
– Automotive Acs (25%)
– ACs & refrigerators (18%)
– Others (5%)

23. – EXTENT OF O3 DEPLETION
• Since 1980s, overall thinning
– Except at Tropics
– Greater over regions located at higher latitudes
» NZ & Aus, Ozone losses upto 30%
» Poles, losses upto 50%
– CONSEQUENCES OF O3 DEPLETION
• IMPACT ON ANIMALS & PLANTS
– Plant tissue damagecrop destructionfood supply decline: Land
– UV too muchplankton diefood chain disturbsupply of fish & extinction of some spp. :Aquatic
• IMPACT ON PEOPLE
– Skin cancer (6000 Americans die/yr) & cataract
– Immune system weakens
• MEASURES TO REDUCE THE IMPACT OF GW & O3 DEPLETION
– INTERNATIONAL EFFORTS
• MONTREAL (CANADA) PROTOCOL (1987)
– treaty, limit production & use of CFCs
– Since 1987, rate of depletion slowing down
– Fig: 10.15, pg 176
• KYOTO PROTOCOL (1997)
– First international meeting
» Treaty (160 nations), > amt of GHG
» Reduce emissions of GHGs by avg of 5.2% by 2012.
– By 2005, 141 countries (55% of global emission), acceded
» Some MEDCs, did not accede to treaty, profits of petro indus, affected by strict emissions
control, many people lose their jobs.
– April 2006, Singapore acceded to Kyoto Protocol

24. – NATIONAL EFFORTS
• USING ALTERNATIVE SOURCES OF ENERGY
– Hybrid cars (petrol+batteries)
• ENFORCING LAWS & REGULATIONS
– Ex Singapore, strict laws
– Govt , helping industries, finding ways to use less energy to do same amt of work.
– Singapore Environment Council (SEC), manufacturers of electrical appliances such as ACs &
refrigerators, energy label, energy efficient.
• REDUCING USE OF CFC’S
– Many countries ban using CFCs
– New alternatives to replace CFCs, ozone friendly chemicals
– INDIVIDUAL EFFORTS
• HELPING TO REDUCE EMISSIONS OF GHG
– Public transport, chose to cycle or walk whenever possible.
– Car-pooling
– Use of energy efficient appliances, use of FF more efficiently
• HELPING TO REDUCE O3 DEPLETION
– Avoid buying products that contain CFCs
• GW & O3 DEPLETION: THE CHALLENGES AHEAD
– Emissions of GHGs are result of human activities
• Industries, continuously devise ways to reduce emissions of GHGs
– Our lifestyles will have to change,
• Every individuals contribution, in a long way.