part 1 sec 3 elective geog gateway 2

1. Chapter 2
Gateway 2
What is
happening to
the Earth’s
climate?

2. Global Climate Change
• The variation in global climate
• Changes in the climatic patterns in the long
term
• General trend has been an irregular but
significant increase in global temperature.

3. Global Warming
• Process where
global
temperatures
increase over a
long period of
time.

4. Global Cooling
• Process where global
temperature decrease
over a long period of
time.

5. Changes since 1880
• Drastic fluctuations on annual basis.
• 5-year mean still fluctuates.
• Over 120 years, mean has risen significantly.
• Increase in temperature is more obvious in
Africa, Parts of Asia and the Arctic.

6. Natural Causes of Climate Change
• There are some natural
phenomena that will cause
climate change.
1. Variations in Solar Output
2. Volcanic Eruptions

7. Variations in Solar Output
• Solar radiation changes as the magnetic field
of the sun changes.
• Increase in magnetic activity will lead to
increase in solar radiation.
• Sunspot activity leads to more solar radiation
emitted.
• Solar activity cycle is linked with earth’s cycle
of high and low global temperature.
– High activity leads to spikes in temperature.

8. What are Sunspots?

9. Volcanic Eruptions
• During eruptions, cabon dioxide, water
vapour, sulphur dioxide, dust and ash are
released into the environment.
• Sulphur dioxide reacts with water to form
sulphur-based particles in the atmosphere.
• These work with the dust and ash to reflect
solar energy back into space, causing global
dimming.

10. Global Dimming
• The gradual reduction in the amount of
sunlight reaching the earth’s surface.
• Causes temporary cooling of the earth.
• Eruption of Mt Pinatubo, 1991, lead to
lowering of temperatures in the northern
hemisphere by as much as 0.6°C.
• Effect can last several years.

11. Greenhouse Effect

12. What is greenhouse effect?
• Process that sustains habitable temperature
on earth.
• Shortwave radiation from the sun reaches
earth as visible light.
• Longwave radiation is heat from the heated
surface of the earth.
– Earth’s surface is heated by the shortwave
radiation from the sun.

13. Process of greenhouse effect
• Shortwave radiation comes from the sun.
• Some of it is reflected and trapped in the
atmosphere by greenhouse gases.
• Some of it passes through and heats up the earth’s
surface.
• The earth’s heated surface emits (gives off) longwave
radiation.
• Some longwave radiation is reflected back by the
atmosphere layer while some escapes.
• The reflected radiation continues to heat up the
earth’s surface.
• This maintains the optimal temperatures on earth for
life to exist.

14. What is enhanced greenhouse effect?
• When greenhouse gases in the atmosphere
increase, the amount of radiation trapped
increases.
• This causes the heat on Earth’s surface to
increase.
• Key greenhouse gases are nitrous oxide (N2O),
carbon dioxide (CO2) and methane (CH4).

15. Who causes this spike?
Burning of Fossil Fuels
• Industries and modern fossil-fuel burning
machines have accounted for the spike in
greenhouse gases.
• Intense spike in all 3 tracked gases since 1500
to date (due to the onset of the Industrial
Revolution and rapid human population
growth)

16. Deforestation
• Loss of forests due to removal and clearance
of tress.
• Commercial value of timber
• Enhance need for agricultural / residential /
commercial land
• Loss of carbon lungs of the earth.
• South America and Southeast Asia are the 2
highest areas of forest loss.

17. Reforestation
• Process where trees are planted to replace
lost forest areas.
• China, India, Vietnam, USA has large scale
reforestation programs.
– When you need to reforest it means that you had
previously done deforestation.
– Reforestation levels often fall short of
deforestation levels.
– Reforestation also tends to be of lesser variety
compared to the original lost species.

18. Changing land use
Agriculture
• Global increase in meat consumption leads to
increased livestocks reared.
• Argentina is one of the world’s largest beef
producers.
• Methane gas emitted from lifestock account for
30% of Argentina’s total greenhouse gas
emissions.
• Widespread use of machines in agriculture
release additional CO2 into the atmosphere.