3.5 Ozone depletion
Page number 46&47
Ozone Layer Definition
“The ozone layer is a region in the earth’s stratosphere that contains high concentrations of ozone and protects the earth from the harmful ultraviolet radiations of the sun.”
What is Ozone Layer Depletion?
Ozone layer depletion is the thinning of the ozone layer present in the upper atmosphere. This happens when the chlorine and bromine atoms in the atmosphere come in contact with ozone and destroy the ozone molecules. One chlorine can destroy 100,000 molecules of ozone. It is destroyed more quickly than it is created.
Some compounds release chlorine and bromine on exposure to high ultraviolet light, which then contributes to ozone layer depletion. Such compounds are known as Ozone Depleting Substances (ODS).
The ozone-depleting substances that contain chlorine include chlorofluorocarbon, carbon tetrachloride, hydrochlorofluorocarbons, and methyl chloroform. Whereas, the ozone-depleting substances that contain bromine are halons, methyl bromide, and hydro bromofluorocarbons.
Chlorofluorocarbons are the most abundant ozone-depleting substance. It is only when the chlorine atom reacts with some other molecule, it does not react with ozone.
Montreal Protocol was proposed in 1987 to stop the use, production and import of ozone-depleting substances and minimise their concentration in the atmosphere to protect the ozone layer of the earth.
What is an Ozone Layer?
The ozone layer is mainly found in the lower portion of the earth’s atmosphere. It has the potential to absorb around 97-99% of the harmful ultraviolet radiations coming from the sun that can damage life on earth. If the ozone layer was absent, millions of people would develop skin diseases and may have weakened immune systems.
However, scientists have discovered a hole in the ozone layer over Antarctica. This has focussed their concern on various environmental issues and steps to control them. The main reasons for the ozone hole are chlorofluorocarbons, carbon tetrachloride, methyl bromide and hydrochlorofluorocarbons.
Let us have a detailed look at the various causes and effects of ozone layer depletion.
Ozone depletion contributes to global warming by allowing more UV radiation to reach Earth, which can affect weather and ecosystems. It also releases greenhouse gases like CFCs that warm the planet.
The Montreal Protocol, signed in 1987, is a global effort that has reduced ozone-depleting chemicals and helped protect the ozone layer.
If harmful emissions stop, the ozone layer could take 50 to 100 years to fully recover.
UV radiation, which is harmful to life, increases on Earth as the ozone layer thins, leading to health and environmental issues.
Ozone depletion is more severe at the poles, especially in Antarctica, while the equator sees more stable ozone levels.
Individuals and industries can help by using ozone-friendly products, supporting the Montreal Protocol, and avoiding chemicals like CFCs.