Transcript Earth - science

Unit 11 – Science and Humanity
October
Title: Task 5: Changes that occur during
the carbon cycle and the effects on
climate change.
•
Prior learning
– There are 3 kinds of rock – sedimentary, metamorphic and Igneous
– Igneous rocks form crystals depending on the length of time it takes them to cool
down
- Theory of continental drift
- Rock cycle
•
Key words
– Photosynthesis, respiration, decomposition, decomposers, decay, carbon, cycle, fossil
fuels, combustion, greenhouse effect, climate change,
Unit 11 – Science and Humanity
IAM LEARNING:
Describe the long-term changes that have occurred in our universe to
our solar system and earth
I WILL BE SUCCESSFUL IS I CAN:
• Identify the changes of the carbon cycle
• Understand what the combustion of fossil fuels are
• Explain the greenhouse effect
• Explain the theory behind climate change
I CAN:
• Complete the stages in the carbon cycle
• Explain how the combustion of fossil fuels impacts on the carbon
cycle and how this in turn impacts on the greenhouse effect
• Explain the link between climate change and fuel consumption and
identify any governmental measures that are or are planned to be
put in place to reduce the effects
STARTER: What am I?
•
I’m a viscous semi-solid with
convection currents circulating in me.
Mantle
•
I’m iron and nickel too, but I’m liquid.
Outer core
•
I just hang around on the outside.
Atmosphere
•
I’m really very thin and am mostly
silicon, oxygen and aluminium.
Crust
•
I am dense, very hot, made mostly of
solid iron and nickel.
Inner core
Unit 11 – Science and Humanity
The early atmosphere
• The Earth was formed about 4,500 million
years ago.
Mars
• During the first billion years there was
intense volcanic activity, which produced the
early atmosphere. This would have contained
large quantities of carbon dioxide (CO2) and
water vapour. Methane (CH4) and ammonia
(NH3) are thought to have also been present.
Venus
• This is rather like the atmosphere on Mars
and Venus today.
• The water vapour condensed to form the
oceans.
Unit 11 – Science and Humanity
Oxygen levels increase
• Carbon dioxide reacted with rocks and much
became trapped in them.
Earth
• The evolution of algae some 3,000 million
years ago, and subsequently plants which
successfully colonized the Earth’s surface,
led us towards the present atmosphere.
• Their photosynthesis replaced carbon
dioxide with oxygen.
• Over a period of time, billions of tonnes of
carbon dioxide became locked up in fossil
fuels.
Photosynthesis
increased
oxygen levels
Unit 11 – Science and Humanity
Nitrogen appears
• As oxygen levels rose, atmospheric ammonia (NH3) reacted
with oxygen(O2) to form water (H2O) and nitrogen (N2).
• Also, living organisms, including denitrifying bacteria,
broke down nitrogen compounds releasing more nitrogen
into the atmosphere.
• And so the atmosphere headed towards a composition that
has remained fairly constant for the last 200 million years.
21%
1%
Nitrogen
Oxygen
Other
78%
Unit 11 – Science and Humanity
Atmosphere timeline
Copy the timeline and arrange the blue boxes in
appropriate places along the line.
4,500
million
No
gases
3,000
million
H2O
N2 O2
2,000
million
1,000
million
CO2
NH3
CH4
500
million
Volcanoes
Algae
200 Now
million
H2
and
He
Plants
Unit 11 – Science and Humanity
Atmosphere Timeline
No
gases
Volcanoes
4,500
million
3,000
million
H2
and
He
Algae
2,000
million
CO2
NH3 CH4
1,000
million
Plants
500
million
200 Now
million
O2
N2 H2O
All positions are approximate
Unit 11 – Science and Humanity
PLENARY: Changing gas levels
1. How long ago was the
atmosphere 75% CO2?
Approx 4,000M
2. How long ago were the CO2
and N2 levels in the
atmosphere equal?
Approx 3,300M
3. How long ago was the
atmosphere 50% nitrogen?
Approx 2,000M
100%
Composition percentage
Use the graph to estimate
the answers.
carbon
dioxide
nitrogen
50%
oxygen
0%
5,000 3,000
now
0
Time (millions of years)
Unit 11 – Science and Humanity
Unit 11 – Science and Humanity
IAM LEARNING:
Describe the long-term changes that have occurred in our universe to
our solar system and earth
I WILL BE SUCCESSFUL IS I CAN:
• Identify the changes of the carbon cycle
• Understand what the combustion of fossil fuels are
• Explain the greenhouse effect
• Explain the theory behind climate change
I CAN:
• Complete the stages in the carbon cycle
• Explain how the combustion of fossil fuels impacts on the carbon
cycle and how this in turn impacts on the greenhouse effect
• Explain the link between climate change and fuel consumption and
identify any governmental measures that are or are planned to be
put in place to reduce the effects
Ozone: a vital filter
• Oxygen normally exists as pairs of
atoms (O2).
• Oxygen can, however, turn into
another form that has three atoms
joined together. This is ozone (O3).
3O2

oxygen
2O3
ozone
Harmful UV rays stopped
with ozone layer
• As oxygen levels rose, so did the
amount of ozone.
• This layer of ozone in the
atmosphere filters out harmful
ultraviolet rays from the sun. This
will have allowed new organisms to
evolve and survive.
Earth
Harmful UV rays reach Earth’s surface
without ozone layer
Unit 11 – Science and Humanity
The carbon cycle
Unit 11 – Science and Humanity
CO2 release or consumption?
Unit 11 – Science and Humanity
Carbon dioxide and
temperature
Over millions of years the carbon cycle
has maintained a constant, low percentage
(approx. 0.03%) of carbon dioxide in the
atmosphere.
In 1860, the CO2 level was about 289 ppm
(parts per million).
Here is a table showing the CO2 levels
over a recent 10-year period.
Year
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
Carbon
dioxide
(ppm)
333.68
335.55
337.14
338.38
340.25
341.82
343.18
344.26
345.99
347.96
What percentage change is this and does it matter?
Unit 11 – Science and Humanity
Changing CO2 concentrations
From air trapped in Antarctic ice, we have a good idea of CO2
concentrations going back 160,000 years.
We also know the temperatures over the same period.
The very warm interglacial period of 130,000 years ago was
accompanied by CO2 levels of around 300 ppm.
The previous great Ice Age had CO2 levels around 200 ppm.
200ppm
CO2
300ppm
CO2
Which label goes with each picture?
Unit 11 – Science and Humanity
The greenhouse
effect
Normally the Earth absorbs heat and
emits heat at the same rate. Because of
this the temperature remains constant.
Certain gases, like CO2 and methane,
act like a greenhouse. They let heat in
but do not let it out. This is called the
greenhouse effect.
balanced
same
Earth
temp
More CO2
This means that the more CO2 there is,
the hotter planet Earth is!
And
hotter
hotter!
hotter
Earth
Unit 11 – Science and Humanity
Work through Task 5:
Effect on Climate
Change using the
information you have
gathered in the past
lessons
Unit 11 – Science and Humanity