Three oxygen atoms combine to form a highly reactive molecule named ozone which is a bluish gas. At about 9.3 to 18.6 miles above the earth, there is a layer of naturally occurring ozone gas. This layer is known as the ozone layer. This layer protects the earth from the ultraviolet B radiation emitted by the sun. These ultraviolet radiations of the sun causes skin cancer and crop failure. Hence for the survival of life on earth, the ozone layer is essential. Since this layer acts as a protective cover, there are concerns surrounding the depletion of the ozone layer. These concerns are amplified by the fact that pollution caused by man’s gadgets are causing this depletion. The main reason for the depletion is ChloroFluroCarbon (CFC). Upon exposure to ultraviolet rays, the CFC breaks down into various substances which include chlorine. This chlorine reacts with the oxygen atoms in ozone, thereby destroying the ozone layer.
1. The Antarctic Ozone Hole
Depletion of the ozone layer was first discovered in the 1980s. The first region discovered to feel the impact of the depleted ozone layer was the Antarctic. Low temperatures in this region, further helped the CFC to convert to chlorine. When the sun shines for a long period of time in a day, the chlorine reacts with the ultraviolet rays to erode ozone on a massive scale. Some times, the erosion is up to 65% which is what is referred by some people as the ozone hole.
CFCs were mainly found in coolants, refrigerants, and various aerosols. When its effect were discovered in the Antarctic, the Montreal protocol was established in 1987 which resulted in reduction of the use of CFC.
2. The Arctic Ozone Hole
After Antarctic, now it is the turn of the Arctic to bear the brunt of the depleted ozone layer. Researches have found that during the spring of 2011, ozone destruction of about 80% was observed about 12 miles above the Arctic ice sheet in the earth’s stratosphere. This was the first instance of the ozone depletion affecting the Arctic region.
Polar Vertex which is a strong spin of swirling winds is caused by Earth’s rotation and by cold temperatures. Polar vertex blocks warmer air from the troposphere and keeps colder air in the stratosphere. This environment is conducive for the stable chlorine gases to break into chlorine monoxide which results in the depletion of ozone.
Winter and spring of 2011 witnessed an unusually strong polar vertex and a long cold period. This is cited to be the reason for the Arctic hole discovered this year. Till date, the scientists are still unsure for the reasons for the unusually strong polar vertex.
The low down
Ozone depletion has both merits and demerits. Ozone layer depletion is harmful not just to the environment, but to all living things from animals to humans. But ozone it self, when comes too close to earth can have delirious effect on both living and non living as it is a powerful oxidant. It can create pollutants like aldehydes and ketones when it reacts with the exhausts released from automobiles. Ozone also causes lot of health problems especially respiratory problems like asthma and bronchitis.
Though there are both merits and demerits, the merits override. More harm is done in the absence of ozone layer as people will get exposed to UV rays. The effects of which can even be catastrophic like a weaker immune system, increased susceptibility to skin cancer, eye damage and cataract .
Ozone has been like a protective blanket around the earth and has enabled life to thrive on this planet. When this starts to deplete, all life forms will be affected which will have a big impact on the food chain.
Agriculture will also get affected. Yields of crops like corn, rice, soya beans, cotton will see a significant drop. Rice needs the help of Cyanobacteria for fixing the atmospheric nitrogen. These bacteria s are highly sensitive to the UV rays and will get killed when exposed to high doses.
Forest ecosystem and the biochemical cycles will also get affected which in turn leads to global warming.
The aquatic ecosystem will get affected as a number of organism from phyto planktons to cyanobacteria and even algae will die when exposed to high levels of UV. This in turn will disrupt the food chain.
The effect on health is also pronounced. Studies have shown that lethality of the diseases and the ease of their spread increases greatly. There will also be increased susceptibility to cancers, skin problems, respiratory disorders and eye problems.
It even affects materials like plastic. These materials will start getting degraded rapidly making them unfit for the use in building and constructions.