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Global Warming
Greenhouse gases are produced by many natural and industrial processes.
It is natural to have greenhouse gases, since these gases maintain the Earth’s temperature at a correct level.
When there is too much of these gases, then the Earth’s temperature rises above normal values, and this causes Global Warming.
Too much greenhouse gases causes global warming.

1. What is the environmental effect of population growth?
:: More and more people need food, energy, transport, manufactured goods, homes, etc.
:: More fossil must thus be burnt to provide the above.
:: This places a strain on the Earth’s resources.
:: There is a general increase in pollution.

2. The lithosphere contains polar molecules. What is the significance of this?
They absorb radiation in the infra-red (heat) region of the spectrum, thus keeping the world warm which helps to support life.

3. List substances responsible for air-pollution.
:: volcanic eruption
:: the carbon monoxide gas from a motor vehicle exhaust
:: sulfur dioxide released from factories
:: burning of coal and oil
:: nitrogen dioxide (brown gas) are emitted from high temperature combustion
:: carbon dioxide
:: methane gas
:: Particulate matter
:: Toxic metals, such as lead, cadmium and copper
:: Chlorofluorocarbons (CFCs), harmful to the ozone layer emitted from products currently banned from use
:: Ammonia (NH3) emitted from agricultural processes
:: Odors, such as from garbage, sewage, and industrial processes
:: Radioactive pollutants produced by nuclear explosions, war explosives, and natural processes such as the radioactive decay of radon

4.1. What is meant by the “greenhouse effect”?
This is the warmth that the Earth experiences because certain gases in the atmosphere trap energy from the sun.

In other words, the greenhouse effect is the process where heat is stored on Earth by the action of “greenhouse” gases. The correct concentration of these gases would result in the correct average temperature for the Earth.

If these gases were absent, then heat would escape back into space.
Earth’s average temperature would be very low and would not be able to sustain life.

The greenhouse effect is natural and crucial for life on Earth.
The problem is that too much of such gases causes global warming!
Earth would get too hot for life as we know it!

4.2. List four of the most important greenhouse gases.
water vapor (36–70%)
carbon dioxide (9–26% )
methane (causes 4–9%)
ozone (causes 3–7%)

Please note that this is based on the gases ability to absorb infra-red (heat) and not based on its concentration in the atmosphere.

5. Explain why there is greater production of greenhouse gases with an increase in human population.
:: greater demand and consumption of products
:: hence a greater number of industrial processes
:: more waste products created
:: more greenhouses gases released

6. Explain why an increase in the concentration of greenhouse gases can cause global warming.
Too high a concentration of greenhouse gases means that too much heat would be absorbed (trapped).
The overall average temperature of the Earth would thus rise.

7. Explain why climate change caused by global warming is regarded as so potentially harmful.
:: An increase in Earth’s average temperature would result in serious consequences such as the polar ice caps melting.
:: This would mean that more fresh water would be released into the ocean, decreasing the concentration of the salt water.
:: This in turn affects the ocean currents, heat distribution, marine life, etc.
:: The entire climate cycles would be affected.
:: Agriculture would be affected, migration of birds and the negative effects on pollination, etc.


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