The last quarter of the 20th century witnessed some desperate measures from various countries to curb the depletion of the ozone layer. As a result, the Montreal Protocol came into existence with the aim of saving this layer by phasing out the use of a range of compounds which were believed to contribute to its depletion.
The efforts were successful to a significant extent, which is the reason we forgot that we even faced this problem. Recent studies, which highlight the relationship between global warming and ozone depletion, have made scientists reconsider some facts. These studies states that the depletion of ozone continues and, this time it is aided by global warming.
An Introduction to the Ozone Layer
Ozone layer is a part of the stratosphere―the second layer of the Earth's atmosphere. While the stratosphere extends to a height of 31.04 miles, the ozone layer starts from 8.07 miles and extends up to 20.42 miles above the surface of the Earth.
This layer is predominantly characterized by the presence of ozone―the oxygen atoms with three molecules, instead of the normal oxygen with two molecules. It is important because it captures the harmful ultraviolet radiations coming from the Sun.
Ozone Layer Depletion
A range of chemical compounds, such as chlorofluorocarbons, methyl bromide, halons, carbon tetrachloride, etc., are known to cause damage to the ozone layer. The molecules of these compounds are light and so, they easily soar in the sky. Once they reach the stratosphere, they trigger a series of reactions, owing to which the molecules of ozone get damaged.
This damage to the ozone makes Earth vulnerable to the Sun's harmful radiations. In fact, the adverse effects of ozone depletion have already started becoming obvious; the ozone hole in Antarctica is the best evidence of the same. Of late, it has also been observed that the ozone layer is getting depleted faster at the poles.
Ozone Layer and the Montreal Protocol
The 'Montreal Protocol on Substances that Deplete the Ozone Layer' was an international agreement designed to protect the ozone layer. Since it came to existence in 1987, it has been subjected to amendment twice; first in 1990 and then in 1992.
This treaty stressed on the requirement of phasing out the compounds which lead to the depletion of the ozone, within a stipulated period. As of today, it has been ratified by 196 nations. Environmentalists believe that if the norms of this agreement are followed, the damage caused to the layer will be reverted by 2050.
The radiations from the Sun have to be reflected back to the outer space, but the concentration of greenhouse gases in the atmosphere traps them within the troposphere. As a result of this, the near-surface temperature of the planet is rising, but the temperature of the stratosphere is decreasing.
Going by the aforementioned facts, we know that the depletion of this layer becomes faster in cold environment. And thus, the fall in temperature of stratosphere, as a result of the heat being trapped within the troposphere, is making the ozone layer more vulnerable to depletion.