environmental science (Green house effect/Global warming)- Mohd salim M.sc. botany ,AMU aligarh 18BTM028

1. Presented by
MOHD. SALIM
18-BTM-028
GK7985

2. Greenhouse effects
 Greenhouse effect is a natural process that warm the
Earth’s surface.

3.  The phenomenon of
‘increasing’ or
‘imbalance’ the day and
night temperature
leading to increasing the
mean temperature of
earth is called
greenhouse effect.
 The mean temperature
of earth is 15˚C.
 Nowadays the mean
temperature has
increased to the (15+0.5-
1) ˚C i.e. 16 ˚C.

4. Major greenhouse gases
Carbon dioxide
methane
Nitrous oxide
Sulfur hexafluoride

5. Description of gases
 Carbon Dioxide (CO2): is a colorless, odorless gas
consisting of molecules made up of two oxygen atoms and
one carbon atom. Carbon dioxide is produced when an
organic carbon compound (such as wood) or
fossilized organic matter, (such as coal, oil, or natural gas)
is burned in the presence of oxygen. Carbon dioxide is
removed from the atmosphere by carbon dioxide "sinks",
such as absorption by seawater and photosynthesis by
ocean-dwelling plankton and land plants, including forests
and grasslands. However, seawater is also a source, of
CO2 to the atmosphere, along with land plants, animals,
and soils, when CO2 is released during respiration.

6.  Methane (CH4): is a colorless, odorless non-toxic gas consisting
of molecules made up of four hydrogen atoms and one carbon
atom. Methane is combustible, and it is the main constituent of
natural gas-a fossil fuel. Methane is released when organic
matter decomposes in low oxygen environments. Natural sources
include wetlands, swamps and marshes, termites, and oceans.
Human sources include the mining of fossil fuels and
transportation of natural gas, digestive processes in ruminant
animals such as cattle, rice paddies and the buried waste in
landfills. Most methane is broken down in the atmosphere by
reacting with small very reactive molecules called hydroxyl (OH)
radicals.
 Nitrous oxide (N2O): is a colorless, non-flammable gas with a
sweetish odor, commonly known as "laughing gas", and
sometimes used as an anesthetic. Nitrous oxide is naturally
produced in the oceans and in rainforests. Man-made sources of
nitrous oxide include the use of fertilizers in agriculture, nylon
and nitric acid production, cars with catalytic converters and the
burning of organic matter. Nitrous oxide is broken down in the
atmosphere by chemical reactions driven by sunlight.

7.  Sulfur hexafluoride (SF6): is an extremely potent greenhouse
gas. SF6 is very persistent, with an atmospheric lifetime of more
than a thousand years. Thus, a relatively small amount of SF6 can
have a significant long-term impact on global climate change.
SF6 is human-made, and the primary user of SF6 is the electric
power industry. Because of its inertness and dielectric
properties, it is the industry's preferred gas for electrical
insulation, current interruption, and arc quenching (to prevent
fires) in the transmission and distribution of electricity. SF6 is
used extensively in high voltage circuit breakers and switchgear,
and in the magnesium metal casting industry.
 CFCs: Chlorofluorocarbons (CFCs) are nontoxic, nonflammable
chemicals containing atoms of carbon, chlorine, and fluorine.
They are used in the manufacture of aerosol sprays, blowing
agents for foams and packing materials, as solvents, and as
refrigerants. CFCs are classified as halocarbons, a class of
compounds that contain atoms of carbon and halogen atoms.
Individual CFC molecules are labeled with a unique numbering
system. For example, the CFC number of 11 indicates the number
of atoms of carbon, hydrogen, fluorine, and chlorine (e.g. CCl3F
as CFC-11).

8. How it greenhouse works
 The greenhouse effect works much the same way on Earth.
Gases in the atmosphere, such as carbon dioxide, trap heat
just like the glass roof of a greenhouse. These heat-trapping
gases are called greenhouse gases.
 During the day, the Sun shines through the atmosphere.
Earth's surface warms up in the sunlight. At night, Earth's
surface cools, releasing heat back into the air. But some of
the heat is trapped by the greenhouse gases in the
atmosphere. That's what keeps our Earth a warm and cozy
58 degrees Fahrenheit (15 degrees Celsius), on average.

10. Consequenses of greenhouse gases
 Melting of polar ice cap
 Decline of endemic animal and plant species
 Increase precipitation
 Increase population of pests
 Global warming
 Decline in agricultural harvest
 Natural disasters: drought and flood
 Decrease supply of clean drinking water
 Changes in the natural ecosystem

11. Management
 Cutting down use of fossil fuels
 Improving efficiency of energy usage
 Reducing deforestation
 Planting trees
 Decrease pollution level

12. Thank you