What is the Ozone Layer?
The atmosphere of the Earth plays a crucial role in making it the only planet with life. Basically, the Earth's atmosphere is divided into five layers - stratosphere being one of them. Within the stratosphere, there lies a layer, made of a specialized form of oxygen, known as the ozone layer. The layer is made up of three oxygen atoms, contradictory to the usual two oxygen atoms. With no demarcated boundary, the ozone layer is found between 10 to 20 miles above the surface of the Earth. This layer traps the harmful ultraviolet-B (UV-B) radiation emitted by the Sun, and hence plays a crucial role in supporting life on the Earth. Read more on layers of the Earth's atmosphere.
Ozone Layer Depletion
The ozone layer is threatened by a range of chemicals which tend to destroy it through a series of chemical reactions. These chemicals, such as chlorofluorocarbons, methyl bromide, etc., are released in the atmosphere owing to various anthropogenic causes, including the use of refrigerants (which release CFCs), and the use of insecticides. As these chemicals reach the stratosphere, they tend to destroy the ozone layer. The molecules of these chemicals have the tendency of breaking the ozone molecules, thus hampering their ability to trap the ultraviolet-B radiation. The rate at which ozone layer depletion takes place increases with the decrease in the temperature.
Ozone Layer and Global Warming
The fact that the fall in temperature increases the rate at which the ozone layer depletion occurs may make a person wonder as to how global 'warming' can cause the ozone layer to deplete, but it does. When we refer to the fact that the global temperatures have soared by 1.8 degree Celsius over the last 100 years, we actually refer to the near surface temperature of the planet. One of the major causes of global warming is the greenhouse effect, wherein a number of greenhouse gases which are released by natural as well as anthropogenic activities, form a layer in the atmosphere, and trap the Sun's radiation which in turn makes the planet warmer. This actually means that the heat which is supposed to be reflected back to the space is trapped within the troposphere. When this heat is trapped, it does cause the temperature in the troposphere to increase, but at the same time, it also causes the temperature of the stratosphere to decrease. As the temperature in the stratosphere falls, the ozone molecules in this layer become vulnerable to destruction by the harmful emissions. And therefore it is said that global warming, even though not directly, does play a significant role in the depletion of the ozone layer