Though related to global warming, depletion of the ozone layer is not caused by the greenhouse effect. The ozone layer is a region in the upper atmosphere that absorbs ultraviolet rays from the sun. The emission of chemical compounds like chlorofluorocarbon (CFC) and halon destroys ozone. CFCs are released from products like old refrigerators, while halons are most commonly found in fire extinguishers.
The total amount of ozone in the stratosphere has declined over the past twenty years. A "hole" in the ozone layer refers to the severe decrease in ozone over polar regions. Scientists believe that global warming will further weaken the ozone layer. As the temperature on the earth's surface gets hotter, the stratosphere (a layer in the earth's atmosphere) will get colder. Though the ozone can naturally repair itself, this effect will slow that process.
