4. Temperature Anomaly
It is a departure from a reference value or a
long term average.
A positiveanomaly indicates that the observed
temperature was warmer than the reference value,
while a negative anomaly indicates that the
observed temperature was cooler than the
reference value.
5. How has global climate
changed?
Source: http://climate.nasa.gov/news/index.cfm?NewsID=249
10. Global Climate Change
Variation in global climate in the long term
General
increasing
trend
Fluctuations in
between, and
decreases in certain
years
11. Global Climate Change
Increase in global
temperatures over a long
period of time GLOBAL
WARMING
Decrease in global
temperatures over a
long period of time
GLOBAL COOLING
13. Climate change in the past 150
years
Significant but irregular temperature rise of 0.3 to
0.6℃ since 1881
Global cooling recorded after WWII for several
decades because of industrial pollution and volcanic
activity
Amount of sunlight that reaches earth’s surface is
reduced because of large amount of particles in the
atmosphere low temperature
Also known as global dimming
Global warming over last century: world warming on
an average of 0.74℃ especially since 1970s
14. Watch the video below to find out
more about climate change
https://www.youtube.com/watch?v=8YQIaOldD
U8
16. Variations in solar output
Sun emits solar radiation at different rates
due to changes in magnetic field
An increase in magnetic activity increase in solar
radiation.
Magnetic activity of the sun has a cycle that lasts
about 11 years.
Through the study of sunspots, the solar activity
cycle was discovered
Many sunspots indicates high solar activity &
higher temperature
17. Watch the video below to find out
about the causes of climate
change
You have to fill in the handout based on what
you watched. You can also use the following
slides below to help you with your handout.
You can also look at your textbook 103-108 for
the answers.
https://www.youtube.com/watch?v=RHrFBOUl
6-8
18. Volcanic Activity
Produces large volumes of carbon dioxide, water
vapour, ash and dust
Sulphur dioxide + water sulphur-based particles in
atmosphere that reflect solar energy back into space
Results in a reduction in amount of sunlight that
reaches earth’s surface: also known as global dimming
E.g. When Mount Pinatubo in Philippines erupted in
1991, 17 million tonnes of sulphur dioxide was released
into atmosphere. The sulphur-based particles reflected
solar energy back into space & lowered temperature in
northern hemisphere by 0.6℃.
19. Volcanic Activity evaluation
Usually have few long-term effects on
climate
Because temporary global cooling effect
will cease once the volcanic dust & ash
settle
E.g. Global climate returned to original
state 2 years after Mount Pinatubo
eruption. The large volume of carbon
dioxide released by volcanoes was still 100
20.
21. Greenhouse Effect
Incoming shortwave radiation from the sun
passes through the greenhouse gases found
in atmosphere
Some shortwave radiation is reflected back to
space
Most shortwave radiation is absorbed by the
earth’s surface which then heats up as a result
The warmed surface of earth emits longwave
radiation to the atmosphere
Greenhouse gases absorb longwave radiation,
warming the atmosphere
22. ENHANCED Greenhouse Effect
Increase in the concentration of greenhouse
gases in atmosphere rise in global
temperatures
Happens when human activity causes
greenhouse gases to be released at a far
greater rate than natural emission of
greenhouse gases
Increase in concentration of carbon dioxide
usually the greatest amongst the greenhouse
23. Burning fossil fuels
Fossil fuels: coal, oil, natural gas
Large amount of fossil fuel burnt for industries,
transportation, electricity etc. gives out
large amount of greenhouse gases, esp.
carbon dioxide
Greater amount of greenhouse gases traps
more heat temperature increase
24. Deforestation
Forests cleared for development, agricultural
and commercial activities like cattle ranching,
commercial logging etc.
Forests absorb billions of tonnes of carbon
dioxide each year via photosynthesis,
absorbing a significant amount of global
greenhouse gas emission.
With deforestation lesser trees to absorb
carbon dioxide larger concentration of CO2 in
atmosphere
25. Deforestation
Soil: very large source of carbon because
carbon is accumulated through decay of
organic matter like dead leave and animals
Exposes soil to sunlight
Increases soil temperature and rate of carbon
oxidation
Causes carbon dioxide to be released from soil
into atmosphere
26. Changing land use- Agriculture
Agriculture
Population increases need for more food
More land used for agriculture (practice of
cultivating land, producing crops & raising
livestock)
But such activities release a lot of greenhouse
gases into atmosphere!
27. Changing land use
Cattle Ranching Rice Cultivation
Cattle release methane as
waste gas
Requires the use of tractors
which run on fossil fuel and it
releases carbon dioxide
Methane is a greenhouse gas Use of fertilisers increases
nitrous oxide in soil and is
eventually released when rain
flows through soil
Dead leaves and manure
(organic matter) releases
methane when they
decompose.
28.
29.
30. Changing land use-
Industrialisation
Industrialisation
A lot of carbon dioxide is produced when fossil
fuels are burnt for manufacturing industries
E.g. manufacturing a mobile phone releases
60kg of carbon dioxide.
Countries like China and India are contributing
more to global carbon dioxide emissions in
recent years due to rapid industrialisation
31. Changing land use-
Urbanisation
Urbanisation
Process by which an increasing number of
people live in urban areas such as
cities/towns.
Large amount of fossil fuels burnt to provide
energy for household activities like cooking,
lighting
High concentration of cars, buses increase
amount of greenhouse gases
Editor's Notes
www.wordle.net
Teacher to type into wordle while students discuss and produce the image. Discuss with students their idea of what is climate change. Address any misconceptions.
How to read the graph:
The term “temperature anomaly” means a departure from a reference value or long-term average. A positive anomaly indicates that the observed temperature was warmer than the reference value, while a negative anomaly indicates that the observed temperature was cooler than the reference value.
Ask students how they will describe the changes of global temperatures.
EG: gradual increase in temperature;
gradual decrease in temperature; and
gradual increase with periods of decrease in temperatures.
The teacher provides key words and adjectives to describe the graph.
To indicate in their handout! Write at the side
To indicate in their handout! Write at the side
To indicate in their handout! Write at the side
But global warming is our focus
Short discussion with students to see if they are aware of both physical and human causes.