The Greenhouse Effect and Global Warming

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The Greenhouse Effect

\(\bullet\) Energy is transferred from the sun to the Earth, through waves, including visible light and infrared light.

\(\bullet\) Some of this energy is absorbed by the Earth, warming it up.

\(\bullet\) The warm Earth emits infrared waves.

\(\bullet\) Some gases in the atmosphere absorb this energy and re-emit it back to the Earth, warming the Earth's surface.

\(\bullet\) This effect is known as the greenhouse effect.

\(\bullet\) The gases that absorb energy are known as greenhouse gases and include methane, carbon dioxide and water vapour.

\(\bullet\) The greenhouse effect is a natural effect.

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Global Warming

Many scientists believe that human activity has caused an increase in the greenhouse effect, causing global warming and climate change.

Since about 1850, there has been a steady increase in the burning of fossil fuels for industry, in the carbon dioxide levels in the atmosphere and in the average temperature of the Earth.

However, CORRELATION DOES NOT MEAN CAUSATION i.e. this does not necessarily show that burning fossil fuels is the cause of global warming.

Arguments against carbon dioxide causing the rise in temperature:

The Earth's temperature goes through cycles of hot and cold

Some say that the initial methods of measuring atmospheric carbon dioxide were inaccurate and that the trends that some arguments depend on may not be fully reliable. We also do not have records of carbon dioxide levels around the world for a very long period, as initial measurements were limited to certain locations

Arguments for carbon dioxide causing the rise in temperature:

There greenhouse effect provides a clear mechanism by which global warming could be caused by the burning of fossil fuels. The principles behind the greenhouse effect have been proven in the laboratory.

The temperature of the Earth's surface and the level of carbon dioxide in the atmosphere have both risen in recent years

Many say that the rise in temperature is greater than would have been expected by the normal temperature cycle.

Some scientists say that the recent activity of the sun should be linked with a fall in temperature, not a rise (And that this is evidence for a man-made cause)

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Climate change

\(\bullet\) Methane is a more powerful greenhouse gas than carbon dioxide

\(\bullet\) It is produced by livestock farming, especially cows.

\(\bullet\) It is also produced by soil bacteria in landfill sites and in rice 'paddy fields'

Potential Effects of Global Warming:

Ice in South Pole and glaciers will melt - This will cause a rise in sea levels and increased flooding in some areas

Animals may be forced out of their natural habitats - Some may become extinct if they cannot survive the warmer temperatures

More extreme weather - Including heavy rainfall, powerful storms and heat waves which could damage wildlife and the growth of crops

Acidic carbon dioxide will dissolve in oceans - Lowering its pH and harming marine organisms