Greenhouse Effect (SL IB Environmental Systems & Societies (ESS))

What is the Greenhouse Effect?

• The Sun emits energy in the form of solar radiation (including visible light and ultraviolet rays) that enters the Earth’s atmosphere
  • Some thermal energy is reflected from the Earth's surface
  • Most thermal energy is absorbed and re-emitted back from the Earth’s surface

• This energy passes through the atmosphere where some thermal energy passes straight through and is emitted into space
• But some thermal energy is absorbed by greenhouse gases such as carbon dioxide, methane and water vapour, and is re-emitted in all directions
  • These gases act like a blanket, allowing sunlight to pass through but preventing a significant amount of the infrared radiation from escaping back into space

• This reduces the thermal energy lost into space and traps it within the Earth’s atmosphere, keeping the Earth warm
• This process is known as the greenhouse effect
  • The greenhouse effect is a naturally occurring phenomenon
  • The greenhouse effect is important to ensure that Earth is warm enough for life
  • If it were not for the insulating effect of greenhouse gases, Earth would see similar dramatic temperature fluctuations to its neighbouring planets
  • Without the greenhouse effect, the average temperature would be much colder, making the planet uninhabitable

Greenhouse gases absorb the radiation that is re-emitted from the Earth's surface, trapping it in the atmosphere