1. GREEN HOUSE EFFECT :
Green house refers to a glass chamber where plants are grown. Temp. inside a
green house is higher than that of the surroundings.
- It is because of the property of the glass which allows the incoming solar
radiations to pass through but prevents the reflected radiations to go out thereby
providing warm effect in the chamber.
- Certain gases in the atmosphere have the same property as that of glass.
- Without these gases the temp. of the earth surface would have been 33o
C
lower than the present one. Temp. of the earth would have been – 18o
C instead of
present +15o
C if these gases were not there/have not acted like glass.
GREEN HOUSE GASES OF THE ATMOSPHERE:
• Are CO2
, CH4
, Nitrous oxide and ozone. In addition to these water vapours
play an important role in enhancing the temp. of the earth.
• These green house gases act as a thermal blanket around the globe raising the
earth surface temperature from effective temp. (Te) of 255K to actual surface
temperature (Ts) of 288K.
Green House effect (θo
C) = Ts – Te i.e. 288 – 255 = 33o
C
• CO2
is the most dominant species followed by CFCs in enhancement effect.

2. Secondary Pollutants.. Green house effect
Carbon dioxide, aerosols, etc

3. CHARACTERISTICS OF GREEN HOUSE GASES
Gas Conc.
(ppm. In
1988)
Annual
Conc.
increase %
Relative
contributio
n
Relative
green house
efficiency
CO2 351 0.4 50% 1
CFCs 0.00225
(2.25 ppb)
5 23% 15000
CH4 1.675 1 11% 25
Nitrous
oxide
0.31 0.2 7% 230

4. Carbon Dioxide :
• Principal source of gas is fossil fuels & deforestation
• CO2
conc. has been raised by 40ppm between 1958 and 1990. For the
last 30 years CO2
has been increasing at a rate of 0.4% per year or 1.5
ppm CO2
is added every year. (2.12 billion tones per ppm raise)
• Between 1800-1990, only 5o
C increase has been recorded (not 0.9o
C as
expected)
• Atmospheric CO2
level may double by 2060 causing 1.5 to 4.5o
C temp.
rise.
Carbon Emission Rates :
- From coal it is 75% more than that from the natural gas.
- From synthetic oil/gas it is 80% more than that from the coal.
- From oil it is 44% more than that from natural gas.
- USA, Western Europe, USSR, Eastern Europe and Japan are the
major contributors in global emission of CO2
.
- Among developing countries in Brazile the emission of CO2
is quite
high due to deforestation activities.

5. Chlorofluoro Carbons (CFCs):
• Like other green house gases, they do not occur naturally but their
presence is due to man made activities.
• They are a group of synthetic compounds which are used as aerosol
propellants, as foaming agents, as refrigerants and as solvents and find
their way into atmosphere.
• Highly stable, 15000 more green house efficiency than CO2
, green
house contribution is 25%, concentration is 2.25 ppb and conc. is
increasing @ 5% per year.
• Have long residence time in atmosphere. CFCl3
has residential time
between 60 to 110 years whereas CF2
Cl2
has residency time ranging
between 55 and 400 years.
• Among CFCs two specific chemicals CFCl3
and CF2Cl2
have been
extensively used.
• The Montreal protocol adopted in 1987 seeks to limit CFC emission
worldwide.
• Even if emissions are significantly reduced their impact already
present in the atmosphere will be felt for centuries.

6. • Developed countries are the main contributor of CFCs, 28% of such
emissions are produced by USA alone, 11% by Japan and USSR and
over 27% by EEC countries.
• All developing countries together constitute less than 5% of global
emission.
Other Green House Gases:
• Methane – Bacterial fermentation from swamps, marshes, rice fields
and digestive systems of ruminants.
– Increased cattle production and increased areas of paddy
cultivation.
– Production, transportation and combustion of fossil fuels biomass
fuels.
– Doubling of methane conc. can lead to 0.2 to 3oC temp. rise.
– Green house efficiency of methane is 25 times more than that of
CO2
increasing at a rate of 1.1% per year. Contribution to global
warming is around 15%.

7. • Nitrous Oxide (N2
O):
Also known as laughing gas is produced naturally, two main sources
are
– increased combustion of fossil fuels
– Consumption of Nitrogen fertilizers.
– Has residential period of 150 years in atmosphere.
– Its conc. is increasing at a rate of 0.2% per year.
– 230 times as potent as CO2
in causing global warming.
– Has a life of around 180 years
– Contributes to about 5% of global warming.
Impact of Green House Enhancement:
1. Increase in Global Temp:
• From 1860-1900 the average world temp. has increased by 0.7o
C.
Temperature of tropical ocean has risen by 0.5o
C.
• With doubling of CO2
conc. from 288 ppm to 560 ppm in the next
100 years the global temp. would increase by 1.5 to 4.5o
C.

8. Effect of global change in Temp.
• Rise in sea level
• Excessive melting of polar ice would lead to a rise in ocean level
by 40 to 120 cms
• Sliding of Antarctic ice sheet will lead to another 5 to 6 metres
sea level rise.
• Flooding in many low lying coastal areas, or submergence of
coastal areas.
• Increased sea surface temperature, increasing frequency of
tropical cyclones and other storms.
• Impact on coastal ecosystems & estuaries (substantial loss of
coral and decrease in biological diversity among marine
organism).
• Increased evaporation, decreased soil moisture content &
increased cloud formation
• More pest infestation
• Increase in respiratory & skin diseases in human beings
• More deaths due to heat stroke

9. • Agriculture
•Shift in food growing
areas.
•Changes in crop yields.
•Increased pests, crop
diseases, and weeds in
warmer areas.
• Biodiversity
•Extinction of some plant
and animal species.
•Loss of habitats.
•Disruption of aquatic
life.
Weather
•Prolonged heat waves and
droughts.
•Increased flooding from
more frequent, intense, and
heavy rainfall in some
areas.
Water resources
•Changes in water supply.
•Decreased water quality.
•Increased drought.
•Increased flooding.
Forests
•Changes in forest .
•composition and location..
•Disappearance of some
•forests.
•Increased fires from drying.
•Loss of wildlife habitat and
species.
•Sea level and coastal areas
•Rising sea levels.
•Flooding of low lying
islands and coastal cities.
•Flooding of coastal
estuaries,wetlands,and coral
reefs.
•Beach erosion.
•Disruption of coastal
fisheries.
Human health
•Increased deaths.
•Disruption of food and water
supplies.
•Spread of tropical diseases to
temperate areas.
•Increased respiratory diseases
and pollen allergies..
Human health
•Increased deaths.
•More environmental refugees.
•Increased migration.

10. Global Effects to tackle the global warming problems :
Prevention and Adaptation strategies :
Toronto Meet June 1988 – Cutting carbon emission by 50% by 2050.
Montreal Protocol, 1987 :
- Immediate freeze on CFCs production
- Reducing production by 50% by 2000 AD
Helsinki Declaration 1989 :
- Pledges to phase out most of the CFCs by 2000 AD.
Climate convention of 1992, Earth Summit :
- Stabilizing atmospheric CO2
by 2050 AD through bringing down
carbon emissions to 2 billion tons per year and ending CFCs
production.

11. ……….GREEN HOUSE EFFECT
The Kyoto Protocol:
- In Dec. 1997, 2200 delegates from 161 nations met in Kyoto, Japan to
negotiate a new treaty to help slow global warming.
- Confirmed scientifically that projected growth of emission of green
house gases would warm up the world climate by upto 5-8o
C by the end of
this century.
- USA the biggest polluter opposed the Kyoto protocol.
Salient features of Kyoto Protocol:
1.The developed countries commit themselves to reducing their collective
emissions of six key green house gases by at least 5%.
2.Each country’s emission target must be achieved by the period 2009-2012.
3.Countries will have a certain degree of flexibility in how to make &
measure their emissions reductions.
4.The member countries will pursue emission cuts in a wide range of
economic sectors.
5.The protocol will advance the implementation of existing commitments by
all countries.

12. Strategies for facing global warming problems :
1. Prevention Strategy (air insurance policy approach):
• Slowing population growth
• Scrubbing of Carbon before or during combustion
• Efficient use of energy
• Levying carbon tax on fossil fuels
• Shift to non-carbon fuels & renewable energy resources
• Reversal of deforestation and reforestation
• Reduction in CFCs production
2. Adaptation Strategy (Protection from consequences) :
• Construction of conveyance systems to redistribute water
• Fortification of sensitive coastal areas
• Population migration to safer areas