2. •Over the last 200 years, industrialization has
taken place. With new machines, sources of
power and transportation, humans now have
the tools to create liveable communities almost
anywhere in the world.
•Now humans live in most parts of the Earth.
We can alter the course of rivers, and even
change the topography of the Earth’s surface
with our great machines and technologies.
Farms too can produce more food than before.

3. •New and better transportation allows food to
move more quickly from place to place. All of
these technological changes not only increase
the food supply but also make it possible for
the Earth to support billions of people.
•However, these changes also have harmful
effects. We share the Earth’s environment
with many other forms of living things. The
large number of people living on Earth has
affected the survival of many of these living
things.

5. •Many kinds of plants and animals are
now extinct. Even the atmosphere has
changed. Changes in Earth’s
temperature caused by global warming,
ozone holes and acid rain are brought
about as result of human activities.

6. •Burning of fuels like coal, oil and gas gives us
energy to power the machinery factories, our
homes and means if transportation. These
burning produces carbon dioxide which keeps
our atmosphere warm enough to support life.
Without it, our planet would be frozen.

7. •Carbon dioxide in the Earth’s atmosphere acts like
the glass of the greenhouse. It lets in sunlight and
prevents the heat given off from escaping back into
outer space.
•This is called the greenhouse effect.
•As humans burn more fuels to power more
machines, the amount if carbon dioxide in our
atmosphere continues to rise. However, too much
carbon dioxide in our atmosphere will make the
Earth too hot for living things to survive.

9. •This is known as global warming. If global
warming continues, it will likely change the
pattern if weather and climate all over the
world.
•These changes will nit be the same
everywhere, summers would become even
hotter and the winters even colder. Larger
and more powerful storms, greater periods of
droughts in some regions, and increased
rainfall in other could all be part of this new
pattern.

10. •Another factor contributing to the increased
amount if carbon dioxide in the atmosphere
is the clear- cutting if rainforests. This is done
to provide land for growing crops and timber
for building. By cutting down trees, humans
are taking away one of the nature’s way of
cleaning the extra carbon dioxide from the
air. However, human activities upset the
balance of the gases in the atmosphere.

12. •All these increase the greenhouse effect and
causes global warming.
•Global warming will change our climate
drastically. It does not mean that everywhere on
Earth is getting hotter. Some places would be
warmer while others actually become colder.
Some would even get drier while others wetter.
The increased heat will change the global pattern
of climate and weather, producing larger and
more powerful storms, greater periods of droughts
in some regions, and increased rainfall in others.

13. •Global warming melts the
ice caps. The heat melts
the ice at the poles,
causing the sea level rise.
A rise in the sea level will
cause low- lying and
coastal regions to be
flooded.

14. •Our atmosphere is made up of many layers.
•Ozone is a molecule that is made up if three
oxygen atoms. It forms a thin layer over the
stratosphere. Ozone, at ground level, is
dangerous to human health.
•In the stratosphere, this ozone layer absorbs
most of the ultraviolet rays from the Sun. it
protects the living things on the Earth from this
harmful ray. It acts as the Earth’s sunscreen.

16. •In the 1970s the scientists discovered that the
ozone layer was rapidly being destroyed. It was
observed that at certain times of the year, the
level of ozone in the ozone layer over the poles
become so sparse that there is virtually a hole in
that ozone layer.
•More harmful ultraviolet rays from the Sun will
now be able to reach the Earth. Ultraviolet rays
affect all life on Earth. There will interfere with
the photosynthetic process, thereby damaging
crops, plants and trees which form the basis of
food chains that support life on Earth.

18. •When CFCs make their way to the upper
atmosphere, they are broken down by
ulrtraviolet rays to release chlorine. The
chlorine released reacts with the ozone in
the ozone layer to release oxygen and
chlorine monoxide. Chlorine monoxide
then combines with an oxygen atom to
produce a molecule of oxygen and a free
chlorine.

19. •The free chlorine atom then reacts with
an ozone molecule, and the cycle repeats.
More and more ozone from the
atmosphere are destroyed, thereby
causing the thinning of the ozone layer.
•Fortunately, many countries in the world
are making laws to reduce the use of
products made with CFCs, such as The
Montreal Protocol in 1987 aimed to reduce
the use of CFC by 50 % by 2000.

21. •Rain, even in polluted areas, is slightly acidic.
This is because carbon dioxide in the air
dissolves in rainwater to form a weak acid called
carbonic acid.
•Besides releasing carbon dioxide, the burning of
oil, coal and gas produces chemicals called
nitrous oxide and sulfur dioxide into the
atmosphere. These chemicals combine with the
water vapor in the air and fall to the ground as
acid rain.

23. EFFECTS OF ACID RAIN
•can damage surfaces of buildings
& statues & kill forests

24. •The acidity of rain increases in
industrial areas. Factories, power station
using fossil fuels and exhaust fume from
motor vehicles contribute to the higher
concentration of chemicals in the air.
•Acid rain has disastrous effects. It kills
fish, destroys trees, erodes the stone
works of buildings and corrodes metals.
Few plants can grow in acidic soil.

26. •Factories, power plants and oil refineries
also increase the amount of greenhouse gases
that are released.
•Burning fossil fuels such as petroleum, gas
and coal releases carbon dioxide.
•Human beings create big cities to live and
work. These cities have many concrete
buildings and large surfaces of black roads,
which absorb and retain heat from the Sun.
This has also resulted in warming.

28. •When acid rain falls on trees, the trees lose their leaves
and are unable to resist pests and diseases. Lakes and
rivers may become too acidic for living things ti
survive.
•We need to reduce the chemicals released into the air.
Industrial power plants should install a device called
“scrubber” in their chimneys to reduce the amount of
sulfur released in the smoke. Motor vehicles should be
fixed with catalytic converters into their exhaust pipes
to reduce the amount of sulfur dioxide produced by the
vehicles. We too should find ways to utilize fuels more
cleanly and efficiently. This will greatly reduce the
possibilities of acid rain developing in the atmosphere.