Transcript The Carbon Cycle

Learning objectives
 Where does carbon enter the
living component of the
ecosystem?
 Where does carbon enter the
non-living component of the
ecosystem?
 What role is played by
saprobiotic organisms in the
carbon cycle?
 What is the greenhouse
effect?
Success criteria
 Be able to construct a flow
diagram to represent the
cycling of carbon through the
environment.
 Develop an understanding of
the greenhouse effect and the
importance of respiration,
photosynthesis and human
activity in giving rise to shortterm fluctuation and longterm change in global carbon
dioxide concentration
What happens to nutrients?
Nutrients are constantly recycled through the carbon cycle and
the nitrogen cycle.
Producers
nutrients in
the soil and
atmosphere
energy and
biomass
energy and
biomass
microbial decomposition
of dead organisms and waste
Decomposers
Consumers
Why is carbon important?
Proteins, fats and sugar all contain carbon. Life without
carbon would be very different and might be impossible.
Carbon is present in the atmosphere as
carbon dioxide (0.04%).
Plants use carbon dioxide during
photosynthesis to produce sugars. The carbon
is then transferred to animals along food chains.
Variations
in CO2
levels
 CO2 levels are greater at night. Why?
 No photosynthesis with out light.
 CO2 levels on a warm summers day are lower than on a
winters day. Why?
 Rate of photosynthesis increased by temperature.
Carbon cycling
 Decomposers – (saprobiotic
organisms) secrete enzymes to
break down complex molecules so
they can be absorbed by diffusion.
They release the carbon as CO2
during respiration.
 If decay is prevented the organism
may become fossilised in to coal,
oil or peat.
Carbon cycling
 Shells and bones of aquatic organisms
can sink to the bottom of the oceans
and form carbon containing
sedimentary rocks such as chalk and
limestone.
 This carbon returns to the atmosphere as CO2 as the rocks
are weathered.
• The oceans contain a massive
reserve of CO2 which helps to keep
the levels of atmospheric CO2 more
or less constant.
So you think you know it all!
Draw the carbon cycle
without referring to your books
The carbon cycle
Increases in global CO2 levels
 In a totally natural situation the carbon cycle would keep
CO2 conc. (ppm)
levels of CO2 in the atmosphere more or less the same.
 Over the past few hundred years however the CO2 in the
atmosphere have increased. Why?
 Combustion of fossil fuels
400
300
 Deforestation
200
100
0
1960
1980
year
2000
What is climate change?
Climate change is a natural phenomenon and normally
takes place over several centuries.
The term ‘climate change’ is being used now to refer to
the current climate. This is because recent scientific
records show that the global climate seems to be
warming up more rapidly than usual.
 The average global temperature has
increased by 0.6°C in 140 years.
 The ten hottest years for the last 100 years
have occurred since 1990.
 Scientists have predicted that the climate could
increase by up to 6°C in the next 150 years.
What could be causing this and should we be concerned?
How is the Earth warmed?
Climate is affected by the conditions
and components of the atmosphere.
The Earth’s atmosphere acts like
the glass in a greenhouse and is
needed to keep the planet warm
enough for life to exist.
Sunlight passes through the Earth’s atmosphere and the
Earth gives out infrared radiation. Certain gases trap some
of this radiation in the atmosphere, which keeps the Earth
warm. This is called the greenhouse effect.
Having some greenhouse gases is a good thing. If it
wasn’t for these gases, Earth would be too cold to live on!
However, too much of a good thing can be bad.
Greenhouse gases
What is global warming?
The term ‘global warming’ is often used
in connection with climate change, but
what does it mean?
Global warming refers to the increase
in the Earth’s temperature due to the
greenhouse effect, which can cause
changes in climate.
However, the term ‘global warming is now being used to
refer to the warming predicted to occur as a result of
increased emissions of greenhouse gases and other
human activities. This enhanced greenhouse effect may
lead to significant climate change.
Remember, global warming and climate change are not
the same thing and should not be used interchangeably.
Global warming
 Climate change - the causes
Learning objectives
 Where does carbon enter the
living component of the
ecosystem?
 Where does carbon enter the
non-living component of the
ecosystem?
 What role is played by
saprobiotic organisms in the
carbon cycle?
 What is the greenhouse
effect?
Success criteria
 Be able to construct a flow
diagram to represent the
cycling of carbon through the
environment.
 Develop an understanding of
the greenhouse effect and the
importance of respiration,
photosynthesis and human
activity in giving rise to shortterm fluctuation and longterm change in global carbon
dioxide concentration