Enhanced Greenhouse Effect and Global Warming

Why Does Global Warming Occur?

• Global warming, or global heating, is attributed to the enhanced greenhouse effect.
• This is caused by the increased concentration of greenhouse gases in the atmosphere.
• Greenhouse gases such as carbon dioxide, methane and nitrous oxides act like a blanket and trap heat inside the Earth's atmosphere.

• As concentrations of these gases build up, they are more effective at preventing heat being lost into space.
• The amount of heat being lost from the atmosphere is less than the energy entering the atmosphere.
• As a result the temperature of the atmosphere increases.

Enhanced Greenhouse Effect vs Normal Greenhouse Effect

Greenhouse Effect

• Solar radiation passes through the Earth's atmosphere.
• The Earth absorbs most of the radiation and warms up.
• The Earth radiates heat energy.
• Some heat escapes into space.
• Some heat is absorbed by greenhouse gases in the atmosphere.
• Greenhouse gases radiate heat in all directions.
• The lower atmosphere remains warm.

Enhanced Greenhouse Effect

• Greenhouse gases allow more solar radiation to pass through the Earth's atmosphere.
• The Earth absorbs most of the radiation and warms up.
• The Earth radiates heat energy.
• Less heat escapes into space.
• More heat is absorbed by the greenhouse gases in the atmosphere.
• Greenhouse gases radiate heat in all directions.
• The lower atmosphere heats up.

Consequences of the Enhanced Greenhouse Effect

• Increasing temperatures of the oceans, land and atmosphere, disrupting ecosystems.
• Climate change, melting snow and ice.
• More frequent extreme weather conditions such as hurricanes, storms, floods, droughts and fires.
• Rising sea levels.
• Increased acidity in the ocean as it absorbs more greenhouse gases.

Wien's Law and the Greenhouse Effect

• The peak wavelength of radiation emitted from the Earth can be calculated using Wien's law.

• This wavelength is in the infrared region.
• Infrared radiation is absorbed by the main greenhouse gases in the atmosphere which re-radiate the energy back into the Earth.