Halocarbons are the substances responsible for the hole in the ozone layer. Though they have been heavily regulated, they are still responsible for some amount of global warming.
Why do I care? Halocarbons are more under control than most greenhouse gases, but they are still having an impact on climate.
Halocarbons are mostly man-made gases consisting of both carbon and at least one of the halogens (fluorine, chlorine, iodine, and bromine). The majority of them fall into the category of Chlorofluorocarbons or CFCs. These gases are most well known for their ability to destroy stratospheric ozone, but they are also very strong greenhouse gases. On average they are thousands of times more efficient at warming than CO2. Fortunately, their concentrations are very small, so their powerful greenhouse effect is limited. Their atmospheric lifespan can range from 1 to 50,000 years. The sources included refrigerants and propellants. Most of these gases have been highly regulated by the Montreal Protocol (1989) and the vast majority of them are decreasing. Though emissions of CFC-12 have almost stopped, it is such a long lived gas that it is still responsible for some global warming as well as the ozone hole.
Links to National Science Education Standards:
Earth Science: EEn.2.6.2 : Explain changes in global climate due to natural processes.
Activities to accompany the information above:
Activity: What is a Greenhouse? (Link to original activity.)
Description: This activity focuses on how a greenhouse retains heat. Students will build a greenhouse model to explain this process.