Global warming refers to the rise in Earth's surface temperature from greenhouse gas emissions. The global temperature is now 1°C higher than in 1900 and projections estimate a further rise of 1-3°C by 2100. The warmest decade on record was 1990-1999 and the warmest year was 1998. Greenhouse gases like carbon dioxide and methane trap heat in the atmosphere and cause global warming. Human activities that contribute to increased greenhouse gases include the burning of fossil fuels, deforestation, livestock production, and use of vehicles. The impacts of global warming include climate change, sea level rise, changes to water availability, effects on human health, extinction of species, and reduced crop yields.

2. Meaning
• The rise in earth’s surface temperature as a
consequence of greenhouse effect is called
Global Warming.

3. • The global temperature is now 1C higher than in 1900.
Predictions of future climate indicate that by the
middle of the next century, the Earth's global
temperature may be 1C to 3C higher than what it is
today.
• Researchers have checked through indirect evidence
(tree rings, coral growth, ice cores) and confirmed that
the warmest decade in the past 1000 years was from
1990 to 1999. The warmest year of the millennium was
1998.

5. Greenhouse Effect
• The thickening of earth atmosphere because of
presence of increased carbon dioxide and other
greenhouse gases is called greenhouse effect.
• These greenhouse gases traps and absorbs
atmospheric heat and ultimately causes Global
warming (an increase earth’s surface temperature).

9. • CFCs: Chlorofluorocarbons, commonly known as CFCs,
are a group of man-made compounds containing
chlorine, fluorine and carbon. Although the amounts of
CFCs in the atmosphere are very small, measured in
parts per trillion (million million), they do contribute
significantly to the enhancement of the natural
greenhouse effect, because they are very good at
trapping heat. Molecule for molecule some CFCs are
thousands of times stronger than carbon dioxide as
greenhouse gases.

10. • Fossil Fuel Burning: A lot of fossil fuel is burnt to meet
the power and energy demand of many industries. This
in turn emits a lot of CO2 and other harmful gases in
the atmosphere.
• Use of vehicles : The rising use of vehicles is
contributing to the CO2 levels in the atmosphere. The
smoke emitted from use of fossil fuel adds to CO2
concentration

12. • Methane Contributors: Methane is another extremely
potent greenhouse gas, ranking right behind CO2.
When organic matter is broken down by bacteria under
oxygen-starved conditions (anaerobic decomposition)
as in rice paddies, methane is produced. The process
also takes place in the intestines of herbivorous
animals, and with the increase in the amount of
concentrated livestock production, the levels of
methane released into the atmosphere is increasing.
Another source of methane is methane clathrate, a
compound containing large amounts of methane
trapped in the crystal structure of ice. As methane
escapes from the seabed, the rate of global warming
will increase significantly.

13. Methane Contribution

15. • Deforestation: The use of forests for fuel (both wood
and for charcoal) is one cause of deforestation, but in
the first world, our appetite for wood and paper
products, our consumption of livestock grazed on
former forest land, and the use of tropical forest lands
for commodities like palm oil plantations contributes to
the mass deforestation of our world. Forests remove
and store carbon dioxide from the atmosphere, and
this deforestation releases large amounts of carbon, as
well as reducing the amount of carbon capture on the
planet.

17. Impacts
• Climate Change: Global warming is causing climate
change. The world’s is becoming warmer and
warmer. There is also prediction of regional climate
changes along the ecosystem.
• Sea Level Change: One major consequence of global
warming arising out of greenhouse effect is the rise in
sea level. Four major changes take place prior to this.
They are: Thermal expansion, mountain glacier
melting, Greenland ice sheet melting and Polar (Arctic
and Antarctic) ice sheet melting. Thus, the coastal
cities and ports may be submerged under sea-water.
Many islands may vanish from the earth surface as
well as from the world map.

18. • Water Balance: Although changes in sea-level have
received much publicity, problems of water availability
are likely to be more serious and perhaps more
expensive to solve. In future, warmer world will face
water crisis in some parts while in other regions it will
be wetter than it is now.
There is uncertainty regarding regional forecasts of
future precipitation as warming of globe makes it
difficult to predict. Also, pattern of agricultural
changes, or effects on ecosystems in general are fairly
unpredictable.
• Human Health: The human health is put at risk
because of Global warming. In recent years, there have
been newer reports of spread of major tropical
diseases with changing climate. As the earth becomes
warmer, more and more people are likely to be
affected by tropical diseases.

19. • Extinction of species: Global Warming is proving to be
threat to a large number of flora and fauna. The rising
levels of water has disrupted many ecosystems thus
reducing the population of many creatures. Among
them most vulnerable are Polar bears and corals.
• Crop Failure: The uneven climatic conditions are not at
all supportive towards crop harvesting. It leads to crop
failure and thus shortage of food for a huge mass.

21. Conclusion