Ozone depletion illustrates two distinct but interconnected phenomena observed since the late 1970’s: a decrease in the total amount of ozone in the Earth’s stratosphere (ozone layer) by about four percent, as well as a much larger stratospheric ozone drop around the polar regions of the Earth in spring.
The latter phenomenon is referred to as the ozone hole. In addition to this famous stratosphere phenomenon, there is also a polar tropospheric ozone depletion event in spring.
Ozone Depletion Causes
The main causes of ozone depletion and ozone holes are derived from industrial chemicals, especially cooling substances, solvents, propellant, and halocarbons foam-blowing agents (Chlorofluorokarbon (CFC), HCFC, Halon), which are referred to as ozone depleting substances (ozone-depleting substances; ODS).
This compound is carried by the wind into the stratosphere after being loaded from the surface. Once these substances are in the stratosphere, they release the halogen atom through photodissociation, which catalyzes the ozone breakdown (O3) into oxygen (O2).
Both types of ozone depletion are observed to occur increases when halocarbon emissions increase.
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Process of ozone depletion
The ozone hole was first discovered in the early 1980, above the Antarctic or South Pole region.
Scientists make observations continuously and it found that larger amounts of the stratosphere ozone concentration decrease.
In addition, ozone depletion also occurs in the North Pole as well as some tropical areas.
Based on the Total Ozone Mapping Spectrometer, ozone damage forms a hole known as the ozone hole in both Earth poles.
Total Ozone Mapping Spectrometer (TOMS) is the satellite instrument of NASA, to measure the value of ozone. Of the five TOMS instruments, four of them successfully entered orbit.
The following process of ozone layer depletion:
- It originated from the emission of gas molecules containing chlorine and bromine resulting from various human activities and natural processes.
- As the gas is unnatural and insoluble in water, the gas molecule accumulates in the lower part of the atmosphere.
- As a result of air movement, the gas molecule will be carried away to a higher atmosphere and reaching the stratosphere.
- In the stratosphere layer, solar radiation breaks down the gas molecules containing chlorine or bromine.
- Chlorine and bromine, then react and break down other gas bonds in the atmosphere including ozone.
- The reaction occurs resulting in a fragmented ozone molecule. Thereby reducing the ozone concentration in the stratosphere.
Depleting areas of the ozone layer
The ozone layer that existed above the Antarctic continent was the thinnest because it was influenced by air pollution occurring since the 1980’s.
Low temperatures in the region also make changes to CFC substances into chlorine that damage the ozone layer.
But, 90 percent of CFC molecules in our planet’s atmosphere originate from industrialized countries in the northern hemisphere.
Efforts to prevent depletion of the ozone layer
Scientists are trying to find ways to prevent the ozone layer from becoming depleted.
In 1989, the state participants of the Montreal protocol agreement agreed to prohibit the production of compounds that triggered the depletion of the ozone layer.
Since then, the number of compounds that can cause ozone layer damage reactions is also reduced.
According to researchers, the possibility of chlorine levels in the atmosphere can return to normal within 50 years. That is, the probability of 2065 ozone holes in Antarctica will shrink in size.
Nevertheless, according to scientists, there is still a lot of human activity that produces CFC substitute compounds, namely HCFC (Hydrochlorofluorocarbon) which still risk damaging the ozone layer.
Then, there is a greenhouse gas that makes the heat trapped and causes climate change to occur.
In 2016 then, the Kigali Amendment Agreement mentioned that 2019 citizens of the world would equally reduce the use of HCFC as much as 80 percent over the next 30 years.
Scientists and companies are attempting to find alternative substitutes to reduce gases that can damage the ozone layer.
As inhabitants of the Earth, we must support it by always paying attention to the impact of the activity we do.