Transcript 8.3 Global warming - science

Key words: combustion, carbon dioxide,
methane,
deforestation
GCSE
CORE
Biology 1b Evolution and Environment
Rising levels of carbon dioxide.
Why?
At the moment the change is
seemingly very small
at 0.060C per year
GCSE
Biology 1b Evolution and Environment
CORE
Objective
How does combustion affect the atmosphere?
Success Criteria
By the end of the lesson I:
• know how combustion affects the
atmosphere
• know how living organisms affect the
atmosphere
• can explain the consequences of global warming
GCSE
Biology 1b Evolution and Environment
CORE
Get the gas right
Pollution problem
Gas
Global warming
Carbon dioxide
Acid rain
Sulfur dioxide and
nitrogen oxides
Holes in the ozone
layer
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CFCs
(Chloroflurocarbons)
Biology 1b Evolution and Environment
CORE
The greenhouse effect
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Biology 1b Evolution and Environment
CORE
Draw a diagram and explain the ‘greenhouse effect’
The greenhouse effect
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Biology 1b Evolution and Environment
CORE
Atmospheric carbon dioxide
The worry of rising carbon dioxide levels is
that
if the earth warms up then the ice caps
will melt causing sea levels to rise.
There is no evidence of this happening
but it would mean
that low lying areas will flood and parts
of or even whole countries will become
submerged!
GCSE
Biology 1b Evolution and Environment
CORE
Carbon dioxide levels
Carbon dioxide is one of the most important greenhouse gases
because atmospheric concentrations have risen dramatically
Respiration and combustion produce
over the past century.Why do you think this is?
carbon dioxide
•Burning fossil fuels (combustion),
Photosynthesis
removes carbon dioxide
•deforestation
and
•flooding land for the construction of hydroelectric
dams More rice fields and cattle have led to
increased levels of methane in the
atmosphere.
have all contributed to
rising levels of
carbon dioxide.
Increased levels of greenhouse gases
(carbon dioxide
methane)
Another greenhouse
effectand
harming
the may
causeisglobal
warming
asproduced
a result of the
environment
methane
which is
Greenhouse
by cows in large amounts
and byeffect
rice fields!
GCSE
Biology 1b Evolution and Environment
CORE
Global warming and greenhouse gases
One of the greatest threats caused by air pollution is
global warming. Global warming is caused by a buildup of greenhouses gases, which leads to an increase in
the Earth’s temperature.
A greenhouse gas is an atmospheric gas
that absorbs infrared light.
Key greenhouses gases include:
 carbon dioxide (CO2)
 methane (CH4)
 water vapour (H2O)
 nitrous oxide (N2O)
GCSE
Biology 1b Evolution and Environment
CORE
Global warming
• Carbon dioxide is
released when fuels like
gas, coal, oil, petrol and
wood are burned.
• Greenhouse gases cause
the temperature of the
Earth to rise slowly.
• This causes climate
change.
• Methane released from
cattle and rice fields is
also a greenhouse gas.
GCSE
Most fuels contain
carbon
Carbon dioxide
released when fuel
burned
Extra carbon dioxide
in the air slows down
heat loss from Earth
Climate change
Biology 1b Evolution and Environment
CORE
What is the carbon sink?
Before the industrial revolution, carbon dioxide levels
were usually kept in check by the carbon sink – forests
and oceans that capture and store carbon.
 forests – All green plants absorb
carbon dioxide as part of
photosynthesis. The absorbed carbon
is only released back into the atmosphere
when the plant dies and rots, or is burned.
 oceans – Carbon dioxide dissolves in
sea water, depending on the temperature
and pressure. Tiny marine animals called
phytoplankton extract carbon from the carbon dioxide
to make their skeletons and shells.
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Biology 1b Evolution and Environment
CORE
The carbon sink
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Biology 1b Evolution and Environment
CORE
Deforestation
Deforestation can have a contributing effect on
global warming.
Large scale deforestation (especially in
tropical areas) has led to an increase of
carbon dioxide in the atmosphere (when
trees die they release their CO2)
It has also reduced the amount of CO2 that is
removed from the atmosphere
Leads to loss of biodiversity.
some organisms lost may have
been needed in the future!
GCSE
Biology 1b Evolution and Environment
CORE
Preventing global warming
• Energy efficiency means less fuel
burned to make electricity.
• Fuel cell buses.
• Renewable energy sources like water
power, solar, wind farms, bio fuels.
• Nuclear power.
• The Kyoto agreement to reduce CO2
emissions.
• Reduction in large scale deforestation
GCSE
Biology 1b Evolution and Environment
CORE
Exam Questions
Give one reason why deforestation increases the
carbon dioxide concentration of the atmosphere. (1
mark)
Explain, as fully as you can, why the increasing
concentration of carbon dioxide in the atmosphere
is causing global warming.
GCSE
Biology 1b Evolution and Environment
CORE
Objective
How does combustion affect the atmosphere?
Success Criteria
By the end of the lesson I:
• know how combustion affects the
atmosphere
• know how living organisms affect the
atmosphere
• can explain the consequences of global warming
GCSE
Biology 1b Evolution and Environment
CORE