Science & Technology in Action

3rd Edition

Climate Change and the Enhanced Greenhouse Effect


A number of factors contribute to changes in the global climate. The effects of such change on temperature, weather and sea-levels are discussed in this lesson.
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Lesson excerpt


Climate change on Earth is not a new phenomenon; there have been many ice ages and warm periods. Based on our understanding of this natural variation, we might expect to be entering a cooler period. However, this is not the case. This is attributed to the enhanced greenhouse effect.

What is the Greenhouse Effect?
As the name implies, the atmosphere around the Earth acts rather like the glass in a greenhouse, ensuring energy balance and conservation. The purpose of a greenhouse is to create favourable conditions that allow delicate plants to grow and this is what the atmosphere does for us.

  • The Sun produces light across a wide spectrum including short wavelengths.
  • The atmosphere is not equally transparent to all wavelengths.
  • Visible light reaches the surface of the earth and much of it is absorbed by the soil and vegetation. The absorbed energy produces heating.
  • As a result the energy is emitted from soil and vegetation as thermal radiation i.e. long wavelength light
  • Most of the thermal radiation is absorbed by certain gases in the atmosphere. These gases are known as theGreenhouse gases, of which CO2 is the most important.
  • The total amount of energy within the atmosphere increases – leading to an increase in temperature.
  • An equilibrium temperature is reached when the loss of heat energy at the top of the atmosphere equals the incoming energy received from the Sun.

The greenhouse effect is essential to life on Earth. It is necessary to maintain a climate that permits water to exist in a liquid state. Without the greenhouse effect we would freeze. The average global temperature would be approximately 30˚C lower and would not be favourable to life as we know it. 

The problem is the enhanced greenhouse effect; too much energy is being trapped, leading to climate change. If this were to continue it would cause major changes to our country and indeed our planet. 

True or False?

  1. Human activity is a significant contributor to the enhanced greenhouse effect. true
  2. Methane is produced in bacterial breakdown of cellulose. true
  3. Oxygen in the air acts as greenhouse gas. false
  4. Carbon dioxide is naturally present in the atmosphere. true
  5. Plants and animals adapt readily to climate change. false
  6. Per head of population, Ireland is one of the lowest emitters of greenhouse gases in the world. false
  7. The enhanced greenhouse effect only causes temperatures to rise. false
  8. Nitrous oxide is the most significant greenhouse gas. false