Greenhouse Gas – Carbon Dioxide
One of the main Greenhouse gases produced is carbon dioxide (CO2). Carbon dioxide is
naturally cycled through earth’s ecosystems through photosynthesis and respiration. Over
Earth’s history the amount of carbon dioxide in the atmosphere has stayed fairly stable as it is
both absorbed into living things and released back into the atmosphere.
However, since the Industrial Revolution, levels of carbon dioxide in the atmosphere have
been steadily rising. Around 27 billion tones of carbon dioxide are emitted into the
atmosphere every year. Some is absorbed but the rest builds up in the atmosphere with:
- 7 billion tones dissolved in the oceans
- 7 billion tonnes taken up by forests
- 12 billion tones accumulating in the atmosphere.
Task 1: What is Carbon dioxide?
Click on the link below and watch the video.
https://www.youtube.com/watch?v=VTbxS9evlkQ
In the box below, write down 6 new things you learnt from watching this video.
Task 2: Structure of carbon dioxide
Carbon dioxide is a naturally occurring chemical compound made from one carbon atom and
two oxygen atoms.
Carbon dioxide is known as a covalent compound. This is because:
- It is a compound made from two non-metal atoms
- The atoms in the compound bond together by sharing their electrons (this is called a
covalent bond).
In fact, carbon dioxide is a compound that has two double covalent bonds. This means that 2
pairs of electrons are shared between each adjacent atom.
Lets look at the diagram below. Oxygen has 6 electrons in its outer electron shell, but requires
2 more electrons to have a full shell – having a full shell means the electron is stable and less
likely to react. Carbon only has 4 electrons in its outer shell, so requires another 4 electrons to
be stable.
In order to do this, each oxygen atom shares two of its electrons with carbon, resulting in
carbon having a full outer electron shell of 8 electrons. Carbon shares two electrons with each
oxygen atom, meaning each oxygen atom can now also have a full outer shell.
Using the internet and the information above, construct definitions for the following key
terms. Understanding these terms will help you understand what climate change is.
Term
Compound
Definition
Molecule
Non-metal
Covalent bond
Double covalent
bond
Task 3: Burning fossil fuels
Use the information presented in the following website to answer the questions below.
http://whatsyourimpact.org/greenhouse-gases/carbon-dioxide-sources
There are natural and human sources of carbon dioxide. Human sources come from activities
such as burning fossil fuels and deforestation.
Fossil fuel use (Combustion)
1. What is a fossil fuel? Give examples.
2. What percentage of human carbon dioxide emissions does this produce?
3. What do we burn fossil fuels for?
4. From combustion, what is the percentage of carbon emission produced by coal, natural
gas and oil?
5. Coal is identified as the most intensive fossil fuel. Explain why.
Electricity/Heat
1. What percentage of carbon dioxide emissions did this sector produce in 2010?
2. Which two countries do not get the majority of their electricity from fossil fuel
combustion?
3. Which country has the biggest fossil fuel combustion? What percentage of their energy
is produced using fossil fuels?
4. Which sector is the largest use of electricity? Why?
Transportation
1. In 2010, what percentage of the carbon emissions came from the transportation
sector?
2. Since 1990, how much have transport emissions grown by?
3. Which human activity counts for the most emissions produced by transport? What is
the percentage?
4. The shipping industry can produce massive amounts of emissions. On average, how
much does this industry produce?
Land Use changes
1. What does “Land Use changes” refer to?
2. What percentage of human carbon dioxide emissions does land usage account for?
3. How much carbon dioxide emission did it produce in 2011?
4. Between 1850 and 200, how much carbon was emitted into the atmosphere through
land use changes?
5. What is Deforestation? Why has it occurred?
6. Trees are carbon sinks. What does this mean?
7. How does deforestation contribute to carbon emissions?
Industrial Processes
1. In 2011, how much carbon dioxide emission did industrial processes produce?
2. What are the four main industrial processes that significantly impact carbon
emissions?
3. How does the production of cement contribute to the formation of carbon dioxide?