back arrow forward arrow

If Earth did not have 'greenhouse gases,' the atmosphere of our planet would be much colder.

Recall that the ability of a gas to cause warming increases as its concentration increases. If the amount of greenhouse gases in the atmosphere rises, the atmosphere could become warmer.

Some greenhouse gases have increased in the last two hundred years due to human activities. One group of anthropogenic compounds that act as greenhouse gases are CFCs (Chlorofluorocarbons). CFCs were commonly used in refrigeration, aerosols, and solvents until they were banned in the late 1980s due to concerns about their contributions to stratospheric ozone thinning.

Worked Example

Question: Are CFCs 'strong' greenhouse gases?

Consider the three factors that influence the effectiveness of a greenhouse gas:

  1. Lifetime: CFCs tend to have long lifetimes. For example, CFC-12 can spend 100 years in the troposphere before diffusing higher up into the stratosphere and affecting the ozone layer.
  2. Concentration: Compared to carbon dioxide, CFCs are not present in very high concentrations.
  3. The region of IR absorbance: CFC molecules peak absorbance is within the peak of Earth's IR emissions spectrum (you can see this by selecting the spectrum of CFC-12 and 'Earth's Emission Curve' in the IR Windows learning tool). Therefore, even low concentrations of CFCs may absorb a significant quantity of IR emitted from Earth.

For questions or concerns, please email us at kcvs@kingsu.ca.
Content subject to KCVS terms of use.
Click here to see our land acknowledgement.
© The King's Centre for Visualization in Science.