What is the Ozone Hole?
In the middle of the 20th century, a collective interest in the human effect on the environment had begun to emerge. Scientists were keenly observing how interference by society in the natural processes of Earth worked out. In the 1970’s, this research led to some interesting observations about the ozone layer and ozone hole of the Earth.
This layer is present in the atmosphere, and it prevents excessive UV radiation from entering into the Earth. It was noticed that there was a steady decline of the ozone in the stratosphere, which comprised of the ozone layer. They also noticed ozone depletion in larger amounts over the two poles of the earth, which is known as the ozone hole.
A layer of gas called ozone sits up around 25-30 kms above the earth’s surface. Ozone is made up of oxygen and is produced naturally in the atmosphere. As the presence of ozone gets reduced in the atmosphere, it causes the ozone layer to get thinner and thinner. The more ozone layer gets thin, the more big gets the size of ozone hole.
Ozone layer is important because it prevents too many harmful ultra violet rays from reaching earth. Ultra violet rays have the capability to destroy plants and animals and can cause skin cancer, cataracts to human beings. Existence of life on earth is possible only because of the presence of ozone layer around the earth.
This ozone depletion was worrisome, because it was taking place at an unprecedented rate.
Climate change and ozone depletion are two global issues that are different but have many connections. In the ozone depletion case, we managed to work with decision makers effectively so that an international agreement called the Montreal Protocol was achieved that essentially solved the ozone depletion problem.
~ Mario J. Molina
According to Wikipedia,
“Ozone depletion describes two distinct but related phenomena observed since the late 1970s: a steady decline of about four percent in the total amount of ozone in Earth’s stratosphere (the ozone layer), and a much larger springtime decrease in stratospheric ozone around Earth’s polar regions. The latter phenomenon is referred to as the ozone hole. In addition to these well-known stratospheric phenomena, there are also springtime polar tropospheric ozone depletion events.”
Causes of Ozone Hole
The destruction of ozone layer is caused by one factor only which is Cholorofluorocarbons.
The main cause of the ozone hole was found to be gases that contained Cholorofluorocarbons (CFCs), Halons and Freons. Found commonly in aerosol cans and released by many electronic appliances, these were seen to decrease the level of ozone in the stratosphere. All of these gases contain chlorine, which is a major cause behind the thinning of the ozone layer.
The presence of chlorine within CFC’s break down the ozone gases in ozone layer which increases the chances of ozone depletion. Till date, CFC’s have accounted for about 80% of ozone depletion.
The destruction of the ozone layer is primarily caused when the amount of gases that contain chlorine begins to increase in the environment. As these gases rise upwards, they are exposed to UV light. This then causes a chemical reaction which creates chlorine atoms. These affect the atoms of ozone and cause ozone depletion.
Although the process has been taking place for several years, the ozone layer was repairing itself naturally. With the marked increase in the emission of these gases, the ozone hole above Antarctica is becoming a permanent part of the layer. Even though the damage is reversible, it will require several decades and a major reduction in the emissions.
CFC’s are not washed back to the earth and are not even destroyed in reaction with other chemicals which means that they can remain the atmosphere for large period of time may be from 20 to 120 years or more. As a result, they are transported back to stratosphere, where they are eventually broken down by UV rays from the sun, releasing free chlorine.
As of now, the ozone hole remains an area of interest for many. Even though the hole present above the Antarctic is beginning to show signs of a decline, there are concerns regarding the long term effects. In particular, many scientists are worried that the development of the same conditions in other parts of the world may cause large scale ozone thinning in the future, if not ozone depletion all together.
Effects of the Ozone Hole
Thinning of ozone layer means getting direct in touch with ultra violet rays which can cause skin cancer or skin irritation which can lead to death. A decrease in 1% of ozone layer can cause 5% increase in cases of skin cancer.
Exposure to UV rays has also increased the cases of cataracts which in turn affects people’s vision and could also cause an increase in people becoming blind.
Depletion of ozone layer and increase in UV rays can also cause DNA damage which can also be catastrophic.
Aquatic plants and animals are not even safe. UV rays can penetrate through water and can kill small plants and animals. If ozone hole keep on expanding, there would be very few plants which means less food in the whole world.
The effect of the ozone hole and the damage done to the layer is still not very well understood. Apart from the gradual decrease of the ozone layer all over the world, there is little quantifiable evidence of new holes appearing any time soon. Even so, a number of countries have been working towards mitigating the damage.
CFC’s have been banned, especially in aerosol cans and various electrical appliances. There have been many conventions held to discuss the methods that will slowly phase out the use of the gases. However, this has been met with a great deal of resistance from industries that are based on the production and use of the gases.
However, the few known and verifiable effects seen within the environment has been a catalyst for change. One of widespread and long lasting effects has been the public awareness towards the environmental issues facing the planet. As one of the first major man-made problems to be discussed on a public forum, it set the ground for public opinion and action on issues such as pollution, greenhouse gases, global warming and the climate crisis.
It also sparked off renewed research about how weather patterns and natural phenomenon may be disturbed small changes in the atmosphere. Ozone depletion is not as serious as it once was, but nonetheless it has had an impact on the planet.
Scientists have been able to determine a number of consequences related to ozone depletion. First is the increase of UVB (Ultraviolet B) light that enters into the atmosphere. This causes environmental damage and problems in human health. Cancer of the skin is being connected to the thinning of the ozone layer.
In the animal kingdom, many species of animals have been found suffering from growing sunburn as a result of increased UV light. Certain crops will also be affected, since they are dependent on cyanobacteria which is quite sensitive to changing levels of the UV radiation. On the other hand, it has also been found that the increased levels allow for the production of more Vitamin D in the animal kingdom.
The ozone layer does not face rampant ozone depletion anymore, as most governments and environmental agencies have worked hard to reduce the emission of CFCs. This has proven to be a success and is the base for further work in reducing dangerous emissions.
Image credit: Flavio&Ken
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