CBSE Class 9 Answered

Chlorofluorocarbons have two major effects in the atmosphere.

1. Greenhouse effect - Chlorofluorocarbons act as greenhouse gases and are considered major contributors to the greenhouse effect. CFCs have created both unnatural atmospheric cooling and warming.

2. Ozone-depletion effect - Chlorofluorocarbons are not destroyed in the lower atmosphere but waft slowly upward toward the stratosphere where they finally break down. Each of the chlorine or bromine atoms released in that breakdown is capable of destroying tens of thousands of ozone (O₃) molecules - thus contributing to the thinning of the protective ozone layer. The loss of ozone allowed more UV light to pass through the stratosphere at a sufficient rate to warm the lower troposphere. The UV rays also cause considerable harm to all living organisms on Earth.

Even though chlorofluorocarbons emissions are being stopped today, the destruction of the stratospheric ozone layer will still continue, because chlorofluorocarbons already released will move slowly up to the stratosphere and destroy ozone for the next 60 to 100 years.