2. Contents covered
• Greenhouse effect
• Greenhouse gases
• Global warming
• Effects of global warming
• Control measures to global warming
5. Greenhouse effect
• The word greenhouse effect holds two meanings.
• One is the natural greenhouse effect which keeps
our earth’s climate normal and comfortable.
• Second one is a manmade greenhouse effect
which is an enhancement of natural greenhouse
effect.
• Made from burning fossil fuels and natural gas.
6. Greenhouse effect
• Greenhouse effect is the process by which
radiation from planet’s atmosphere warms the
planet’s surface to a temperature above what it
would be without this atmosphere.
• Greenhouse effect is the trapping of the sun's
warmth in a planet's lower atmosphere, due to
the greater transparency of the atmosphere to
visible radiation from the sun than to infrared
radiation emitted from the planet's surface.
7. Greenhouse effect
• Earth receives energy from sun in the form of UV,
visible and near infrared radiation. About 26% of the
incoming energy is reflected to space by atmosphere.
• Most of the remaining energy is absorbed at the
surface of the earth and radiated into atmosphere.
• Few gases in atmosphere are active in radiating
energy. These gases radiate energy in all directions.
• Part of this radiation is directed towards the earth’s
surface and warming it. This phenomenon is called as
greenhouse effect.
9. Greenhouse gases
Carbon dioxide
• Sources – fossil fuel burning, deforestation
and plant burning.
• Average time in troposphere – 50 to 120
years.
• Approximately 18 billion tons of carbon
dioxide is added to the atmosphere every
year.
• It is raising at a rate of 0.5% per year.
10. Greenhouse gases
Methane
• The sources – coal mines, burning of coal, land
fills, gas leaks from oil, oil production, decay of
organic matter under anaerobic conditions.
• Average time in troposphere – 10 to 12 years.
• Can cause greenhouse effect 23 times greater
than that of carbon dioxide.
11. Greenhouse gases
Nitrous oxide
• Sources – fossil fuel burning, fertilizers, live
stock wastes and nylon production.
• Average time in troposphere – 114 to 120
years.
• Can cause greenhouse effect 296 times
greater than that of carbon dioxide.
• It is raising at rate of 0.3% per year.
12. Greenhouse gases
Chlorofluorocarbons
• Sources – A.C.s, refrigerators, plastic foams, etc.
• Average time in troposphere – 11 to 120 years.
• It can cause greenhouse effect 900 to 8300 times
greater than that of carbon dioxide.
• Hydro chlorofluorocarbons can be in troposphere
around 9 to 390 years. They can cause
greenhouse effect 700 to 2000 times greater than
that of carbon dioxide.
13. Global warming
• The increase of atmospheric temperature near earth’s
surface as a result of greenhouse effect is called as global
warming.
• The reasons for global warming are:
Increase in the concentration of greenhouse gases in
atmosphere.
Rise in population and urbanization
Industrialization
Deforestation
Burning of vegetation and other organic materials
Use of inorganic fertilizers which release nitrous oxide
into atmosphere
15. Effects of global warming
• Shows various effects on agricultural fields
and decrease the yield of agriculture.
• Changes in forest types and their behaviour,
increase in frequency of forest fires and loss of
wild life.
• Extreme changes in climate and increase heat
waves and droughts.
• Causes heavy rainfall in some areas and heavy
droughts in some areas.
17. Effects of global warming
• Decreases availability of water resources and
decline in water quality.
• disruption of eco-system, loss bio-diversity,
changes in species pattern and genetic disorders
on large scale.
• Health/ mental disturbances, respiratory
diseases, allergies, water pollution, increase in
death rate, etc.
• Effects nutrient cycles i.e. carbon cycle, sulphur
cycle, phosphorous cycle and nitrogen cycle in
water and atmosphere.
19. Control measure to global warming
• Reduce deforestation
• planting more trees
• Developing a way to sustainable agriculture
• Sequester carbon dioxide in deep oceans
• Drastic reduction in consumption of fossil fuels
especially coal
• Increased dependence on renewable energy
sources
• Limit human population to urban areas
• Following environmentally compatible life style