the greenhouse-effect

1. THE GREENHOUSE
EFFECT

2. The Green House Effect
 “The green house effect is a process by which infrared
radiation leaving earth’s surface is trapped by some green
house gases, so the temperature is higher than it would be
if direct heating by solar radiation were the only warming
mechanism.”

3. Warming Mechanism
 1. Short wave radiation from the sun penetrates Earth’s
atmosphere (incoming solar radiation = 343 Watt/m2)
 2. Some solar radiation is reflected by the atmosphere
and earth’s surface (outgoing solar radiation = 103
Watt/m2)
 3. Net incoming solar radiation = 240 Watt/m2
 4. Solar energy is absorbed by the earth’s surface (168
Watt/m2) and warms it and is converted into heat causing
the emission of longwave (infrared) radiation back to the
atmosphere.

4. Warming Mechanism
 5. Some of the infrared radiation is absorbed and re-
emitted by the greenhouse gases. The direct effect is the
warming of the earth’s surface and the troposphere.
Earth’s surface gains more heat and infrared radiation is
emitted again. By this process, some of the infrared
radiation is trapped in the atmosphere by greenhouse
gases causing a warming of Earth’s climate.
 6. Some of the infrared radiation passes through the
atmosphere and is lost in space. (Net outgoing infrared
radiation = 240 Watt/m2).
 The sum up, the green house effect is the rise in
temperature that the earth experiences because certain
gases in the atmosphere trap energy from the sun.

5. Warming Mechanism

6. Earth’s Climate
System
Sun
IceOceanLand
Sub-surface Earth
Atmosphere
Terrestrial
radiation
About 31%
reflected
into space
69% absorbed at surface
Solar
radiation

7. Composition of the Atmosphere
Nitrogen N2 78.084%
Oxygen O2 20.948%
Argon Ar 0.934%
 Carbon Dioxide CO2 0.036% (360 ppmv)
 Methane CH4 1.7 ppmv
Hydrogen H2 0.55 ppmv
 Nitrous Oxide N2O 0.31 ppmv
 Ozone O3 10-500 ppbv (troposphere)
0.5-10 ppmv (stratosphere)
 Water H2O 100 pptv – 4%
Greenhouse
Gases
A greenhouse gas is one that absorbs terrestrial (LW)
radiation, i.e. emitted from the Earth’s surface/atmosphere

8. Greenhouse Gases
• Carbon Dioxide (CO2)
– Source: Fossil fuel burning, deforestation
 Anthropogenic increase: 30%
 Average atmospheric residence time: 500
years
 Methane (CH4)
– Source: Rice cultivation, cattle & sheep
ranching, decay from landfills, mining
 Anthropogenic increase: 145%
 Average atmospheric residence time: 7-10
years

9. Greenhouse Gases
• Nitrous oxide (N2O)
• Source: Industry and agriculture (fertilizers)
• Anthropogenic increase: 15%
• Average atmospheric residence time: 140-190 years
• Water Vapor (H2O)
• The most important Greenhouse Gas!!
• Sources: Evaporation
• Anthropogenic increase: 35 %

10. More greenhouse gases means more
heat trapped which increases the
Earth’s temperature
Burning Natural Gas, coal, oil raises the level of co2 in the
atmosphere
Some farming practices and land-use changes increases the levels
of methane and nitrous oxide
Many factories produce long lasting industrial gases that do not
occur naturally
And those gases enhance the greenhouse effect

11. Even more ways these gases are
added to the atmosphere!
Deforestation: Trees use co2 and give off o2 in which helps to create
the optimal balance of gases in the atmosphere. As more forests are
logged for timber or cut down to make way for farming, there are
fewer trees to perform this critical function. In addition when this
wood is burned it produces even more co2 in the atmosphere.

12. Population Growth
As more people use fossil fuels for heat, transportation and
industry, the level of greenhouse gases continue to increase. AS
more farming occurs to feed millions of new people, more
greenhouse gases enter the atmosphere

15. Effects of Global Warming due to the
unbalance of greenhouse gases
Increased Temperature Rising Sea Level

16. Effects of Global Warming due to the
unbalance of greenhouse gases
Habitat Damage and Species
Extinction
Changes in water supply;
contamination of fresh
water

17. Effects of Global Warming due to the
unbalance of greenhouse gases
More severe storms; hurricanes and
floods
Droughts, changes in weather
patterns

18. Some Proof of Global Warming
Portage Glacier Alaska then…. Portage Glacier Alaska now….

19. 1.Temperature rising
2. Ice melting
3. Land submerging
4. Sea level rising
5. Habitat loss
6. Recursive disaster
7. Salinity
Effects of global warming on Bangladesh
On nature On human

20. Effects of global warming on Bangladesh
On nature On human
1. Habitat loss (17 %)
2. Migration problem
3. Loss of agriculture
Affected People: 15 %
Migration of 27 million
Due to recursive disaster
&
salinity in coastal areas

21. What can we do to help reduce
greenhouse gas emissions?

22. Educate and Use!!
Wind Power Solar Power

23. Educate and Use!!
Fuel Efficient Cars
Compact
Fluorescent

24. Remedial mearures:
 (i) Enhance energy efficiency during use by adding insulation to your walls,
using CFL bulbs etc.
 (ii) Reduce transport sector emissions by less and smart driving.
 (iii) Promote renewable energy (like solar energy) usage.
 (iv) Remove subsidies on fossil fuels.
 (v) Favour sustainable agriculture.
 (vi) Recover methane emissions through waste management.
 (vii) Promote afforestation and reforestations, a single tree will absorb
approximately one ton of CO2 during its life time.
 (viii) Reduce energy consumption by using energy efficient home appliances.
 (ix) Avoid methane production from biomass decay through controlled
combustion.
 (x) Enhance energy efficiency during generation, transmission and
distribution.
 (xi) Reduce waste, prefer reusable products, recycle paper, plastic, metals,
etc.
 (xii) Eat locally grown fruits and vegetables and not the imported ones. The
later requires the burning of fossil fuels for transport.