1. Climate Change in Hong Kong
Climate change has become a hot topic for discussion among members of
the public in recent years. This PowerPoint presentation is intended to
introduce to students the basic knowledge of climate change; its impact
and what actions we as individuals may take to mitigate climate change.
(Suitable for primary school)

2. Breathing breathe in oxygen breathe out carbon dioxide
There is a close relationship between the carbon dioxide in air and
climate change. Air contains carbon dioxide. When we breathe, we
take in oxygen and give out carbon dioxide.

3. Photosynthesis in plant
breathe out oxygen
breathe in carbon dioxide
The photosynthesis process of plants does just the opposite of our
breathing. Green plants carry out photosynthesis under the sun, taking
in carbon dioxide and giving out oxygen, hence green plants help to
reduce the amount of carbon dioxide in air.

4. Burning and electricity generation
carbon dioxide
carbon dioxide
Like breathing, burning such as cooking or having barbeque gives off
carbon dioxide. We may not be aware that the process of generating
electricity will also produce a large amount of carbon dioxide. At
present, most electric power plants depend on burning fossil fuel such as
coal, petroleum or natural gas to generate electricity.
power plant
cooking with fire
burning of coal , petroleum and natural gas to generate electricity

5. The sun gives energy to the earth
sunlight
heating of the earth
Why carbon dioxide can bring about changes in the climate of the earth?
The heat content of the earth surface is mainly from the sun. When sun
light shines on the surface of the earth, the earth will heat up.

6. Heat dissipation by the earth heat dissipation by infra-red radiation
sunlight
After receiving the heat, the earth will radiate the heat back to space. As
a matter of fact, the amount of heat received from the sun and the amount
of heat the earth radiated out to space is more or less the same in the long
run. Nature is in equilibrium.

7. Carbon dioxide lowers heat dissipation
carbon dioxide in the atmosphere
The carbon dioxide in air can hinder the heat to radiate back to space.
As such, carbon dioxide acts like a blanket, hinders the earth from losing
heat.

8. Relationship between carbon dioxide and the earth’s temperature
increase carbon dioxide in the air
If the amount of carbon dioxide in air increases, the capability of the earth
to shed the excess heat will reduce. In response, the temperature of the
earth will rise, resulting to what is known as global warming.
decrease heat dissipation by the earth
rise in global air temperature

9. Use of electricity leads to the rise in global temperature
require burning of coal, petroleum and natural gas,
release carbon dioxide into the air
In our daily life, quite a lot of our activities, i.e. using electrical
appliances, will have an impact on the air temperature indirectly. We
need electricity to drive our electrical appliances. To meet our need, the
electrical power companies burn coal, petroleum or natural gas to
generate electricity, in doing so, put carbon dioxide into the air. The
amount of carbon dioxide in the air increases, so as the air temperatures.
rise in temperature
use of electrical appliance

10. Use of paper and wooden furniture lead to the rise in global temperature
less trees to absorb carbon dioxide
rise in temperature
The material for making paper and wooden furniture comes from trees.
The use of paper and wooden furniture requires chopping down of a large
amount of trees. Reducing the number of trees to absorb carbon dioxide,
the temperature of the whole earth will rise.
use paper and wooden furniture
Trees are cut down to make paper and furniture

11. Rise in sea level - expansion of water by heating
- melting of ice on land
Global warming will lead to sea level rise. Two reasons could be
identified, i.e. (i) thermal expansion of sea water and (ii) melting of
ice/snow on land and the water produced flows into the sea.

12. Expansion of water by heating
water expands when heated, water level rises as a result
water
water
As shown in the experiment in the figure, when water temperature
increases, the volume of water will increase due to thermal expansion.
Since water cannot move sideway inside the container, the water level
will rise. When sea water heats up, the sea level will rise in the same
way.
Rise in global sea temperature leads to expansion of sea water and a rise in sea level
heating

13. Melting of ice caps in polar land and glaciers in high mountains
1928
2000
Global warming will cause the glaciers on high mountains and on land in
the polar regions to melt. This will make it increasingly difficult for
animals like polar bears, seals, sea lions and penguins to find suitable
habitats. As for us, we would find scenic skiing and touring sites
disappearing.
( Source : US Geological Survey)

14. Rise in sea level by melting of glaciers
ice block
ice block
water
water
As shown in the experiment in the figure, when ice melts, it will turn into
water. When more ice cubes in the funnel melt, more melted water will
flow into the flask and the water level in the flask will rise. With the
same principle, when glaciers melt and turn into water, the water will
flow into the sea and the sea level will rise.
more ice blocks melt, the water level in the flask will rise
ice blocks melt, water flows into the flask

15. Easier flooding of coastal areas during typhoon attack or heavy rain
Sea level rise makes flooding of the coastal areas easier
waves caused by typhoon
coast
rose in sea level
coast
A rise in sea level may submerge some small island states which are
established on coral atoll reefs. It will also cause flooding of the
low-lying coastal region. Moreover, as illustrated in the figure, if there
is a rise in sea level, it will make it easier for the coastal regions to be
flooded during typhoon attacks or rainstorm events.
(Source: US National oceanic and Atmospheric Administration)
Easier flooding of coastal areas during typhoon attack or heavy rain

16. Getting hotter and hotter
Weather becomes hotter and hotter with global warming. Outdoor
activities could become a hardship.

17. More and more heavy rain
Global warming will make the weather unstable. There will be more
rainstorm events. Heavy rain may bring landslides which pose a threat
to hiking activities.
( Source : Geotechnical Engineering Office )
dangerous to picnic and hiking activities
leads to landslide

18. More and more mosquitoes
Mosquitoes thrive better in a hotter environment. In Hong Kong, more
mosquitoes can be found in summer than in winter. With a rise in
temperature, the number of mosquitoes will rise too. This will make it
easier for mosquito-related infectious diseases such as dengue fever to
develop.
more mosquitoes, easier to transmit dengue fever
( Source : HK Education City, and Food and Environmental Hygiene Department )

19. Can air-conditioner stop global warming? No!
increase in electricity usage, require burning of more coal, petroleum or natural gas, release more carbon dioxide, result in global temperature rise
Many students may have a wrong concept, thinking that air-conditioning
is the solution to global warming. All we need is to turn the air
temperature down, we will not be affected. It is true that doing this can
lower the temperature inside a room. However, it would increase the
demand for electricity, and in turn more coal, petroleum and natural gas
will be burnt to generate the electricity needed, more carbon dioxide will
be emitted to the air which will make the temperature of the earth to
increase further. It is a vicious cycle.
turn on air-conditioner and lower the conditioner’s temperature
drop in indoor temperature

20. What should I do? Save electricity
Climate change is of great concern to us. What can we do to stop the
earth in having fever? We can save electricity, say by keeping the
window open in summer as far as possible, hence reduce the use of
air-conditioning. If air-conditioning is used, avoid setting the
temperature too low; turn off electrical appliances when not in use; use
energy efficient (i.e. can save electricity) electrical appliances, etc.
(Source : Electrical and Mechanical Services Department)

21. Take care of trees Prevent hill fire Save paper Plant more trees
Apart from saving electricity, students can actively participate in tree
planting activities. Protect the trees and prevent hill fire. Besides,
since paper is made of wood from trees, it makes sense to save paper.
Plant more trees
(Source: Agriculture, Fisheries and Conservation Department)

22. Reduce expenditure
Reduce consumption is also a viable measure. Since the production
processes of all commercial goods required the use of a large amount of
energy, hence producing carbon dioxide. (At this point, students may be
encouraged to give examples of other viable mitigation measures).
Large amount of energy is used to produce commercial products and release carbon dioxide

23. Save the earth, count me in！
“Save the earth, count me in!” The earth is our home. We should
stand up and take action right now. Let us save the earth and slow down
climate change.