Ozone depletion causes and its potential recovery


The ozone that encircles our planet is crucial for our survival. It’s primary function is to reduce the solar penetration into the earth's atmosphere. The ozone layer (stratosphere) absorbs most of the harmful radiation from the sun protecting us humans. The ozone layer that protects us from strong UV sunlight was and has been slowly disappearing, causing large threats to us human beings. Ultraviolet rays can harm us in several ways. The most common are skin burns, damaging our DNA as well as skin cancer. The ozone layer around the early 1980s was thinning year by year over Antarctica. It would get thinner each August and September.




The ozone layer in the upper atmosphere is made out of O3. The ozone is made by the radiation hitting O2 molecules and then forcing them to form O3 molecules which make up the ozone layer. Over time the ozone breaks down back into 02. However, simultaneously it builds back up as there is constant and plenty UV constantly entering the earth's surface. This therefore then keeps a balance between the ozone breaking and being made.


The molecule O3 that makes up the ozone layer of our planet.



The chemical chlorinated fluorocarbons result in the ozone breaking down much faster than the rate at which it is rebuilt. This is a chemical that contains atoms of carbon, chlorine and fluorine often used in the manufacturing of packaging or aerosol spray. Though it was useful for many products it contributed a lot towards the ozone depletion. CFCs act as a catalyst and assist the breakdown of O3. Previously, it wasn't a great deal as CFC would not be present in the upper atmosphere but now due to industrial production increase, this has now become a large threat. The higher demand for cooling such as air conditioners and refrigerators have enlarged this problem. The significant increase rate of CFCs escaping into the atmosphere is alarming. Eventually, CFC molecules are brought up to the upper atmosphere where the ozone is plentiful. However, that is no longer the case since CFC acts upon ozone. One single CFC molecule can affect a large number of ozone molecules (O3) due to it not being used up in reactions and remaining as a usable catalyst for a prolonged period of time. CFC does leave the atmosphere but the problem is the fact that on ground level consumers have unlimited wants and keep demanding for more. This then leads to more and more products releasing CFC constantly.



How CFCs interact with the ozone molecules, O3 and thereby deplete the ozone layer.


Montreal Protocol-

In 1987 nations came together to create a ban called the Montreal Protocol where participants had agreed to phase out the chemicals that harmed ozone. This meant that the production of ozone-depleting chemicals was banned which consisted of CFCs (chlorofluorocarbons). This chemical stays in the atmosphere for a long time, therefore, it would take decades after the treaty ban to see it’s positive effects. As a fact in 2000 the ozone hole was at its largest ever observed by scientists. But slowly conditions of the depletion have improved and the layer has slowly built back up. As such NASA shows a 20% depletion decrease between 2005 and 2016. It is predicted that the ozone hole over Antarctica will mostly be recovered in the middle of the 21st century. If the success of closing the ozone hole over Antarctica works it would become one of the globe's greatest and most successful environmental restoration projects.


The Montreal Protocol had made sure that the world's developed nations cut HCFC consumption and production by 75 percent. It will then become illegal to import, produce or sell Freon (HCFC-22) and HCFC-142b, the ubiquitous refrigerants, for use in new equipment. At the same time, Europe had implemented a ban on HFC-134a (used in a car for air-conditioning refrigerants that can trap 3,400 times more heat in the atmosphere than CO2), that began in 2011.


The problem is that under the Montreal Protocol, hydrofluorocarbons (HFCs) were promoted as the environmental alternative to ozone-depleting hydrochlorofluorocarbons (HCFCs), which had become the standard working coolant in refrigerators, air conditioners and aerosol cans. HCFCs were already originally the replacement of the even more ozone-depleting chlorofluorocarbons (CFCs). HFCs do not necessarily destroy the ozone layer but they can be thousands of times more harmful to Earth's climate than carbon dioxide.


Both HCFCs and HFCs are chemicals designed to trap heat. The fluorinated part of HFCs turns the normal hydrocarbon into something more durable. When both the properties, durability and heat trapping are combined in the atmosphere, it starts to act as a greenhouse gas.



The effects of CFCs on the ozone layer and thus on the incoming UV radiations.

The alternatives-

  • Natural refrigerants such as hydrocarbons (propane, isobutane and cyclopentane), ammonia could be used as cooling agents in cooling units such as refrigerators and air conditioners. The benefits of these are that they have lower global warming potentials and are available in large quantities.

  • A new group of fluorochemicals called hydrofluoro-olefins (HFOs).

  • In Europe, the chemical industry giants DuPont and Honeywell, found that HFO-1234yf was a potentially good alternative. It seems to have a low global warming effect and doesn't cause ozone depletion. However, there are several concerns on the negative side effects employees handling these chemicals may receive as well as it being flammable.

As well as carbon dioxide. "CO2 is an excellent refrigerant with superior thermodynamic and transport properties, compared to the HFCs in use today," says David Hinde (he is a manager of research and development for Conyers, Ga.). This company became the first company to receive EPA approval to replace HCFCs with CO2 in supermarkets. "By using CO2, refrigeration systems will be able to reduce HFC leaks as well as dramatically reduce the HFC charge (the amount used in a system)."

CO2 can remove heat from the air. the refrigerator as such starts to compress and condense CO2 which causes it to raise pressure and temperature. This gas is transferred to a gas cooler where heat within is released and subsequently cools the refrigerant. The release of heat is through the back or bottom of a fridge through its radiator. CO2 expands into vapor allowing it to evaporate and absorb heat at the same time and thereby, cooling the air.


Slowly conditions of the depletion have improved and the layer has slowly built back up. As such NASA shows a 20% depletion decrease between 2005 and 2016. It is predicted that the ozone hole over Antarctica will mostly be recovered in the middle of the 21st century. Complete recovery can take decades. CFCs have a lifespan of around 50 to 100 years, meaning they remain in the atmosphere for a very long time.



The ozone layer is healing. It’s been 34 years since the global community agreed to the Montreal Protocol, which banned ozone depleting substances.


Works Cited:

Global warming caused by chlorofluorocarbons, not carbon dioxide, new study says. (2013, May 30). Phys.org - News and Articles on Science and Technology.

https://phys.org/news/2013-05-global-chlorofluorocarbons-carbon-dioxide.html


First direct proof of ozone hole recovery due to chemicals ban. (2018, January 4). NASA.

https://www.nasa.gov/feature/goddard/2018/nasa-study-first-direct-proof-of-ozone-hole-recovery-due-to-chemicals-ban


Conrad, K. (2020, May 24). What is the ozone hole? WorldAtlas.

https://www.worldatlas.com/articles/what-is-the-ozone-hole.html


Kintisch, E. (2014, October 7). Can sucking CO2 out of the atmosphere really work? MIT Technology Review.

https://www.technologyreview.com/s/531346/can-sucking-co2-out-of-the-atmosphere-really-work/


If holes are forming in earth's outer atmosphere, why doesn't the air in the planet violently vacuum out? - Quora. (n.d.). A place to share knowledge and better understand the world.

https://www.quora.com/If-holes-are-forming-in-Earths-outer-atmosphere-why-doesnt-the-air-in-the-planet-violently-vacuum-out



Image Sources:

The molecule O3 that makes up the ozone layer of our planet.

https://www.vectorstock.com/royalty-free-vector/o3-ozone-molecule-vector-8752208


How CFCs interact with the ozone molecules, O3 and thereby deplete the ozone layer. https://www.researchgate.net/figre/Mechanism-of-Ozone-Layer-Destruction-by-CFC-in-Stratosphere_fig4_228279972

The effects of CFCs on the ozone layer and thus on the incoming UV radiations. https://www.worldatlas.com/articles/what-is-the-ozone-hole.html

The ozone layer is healing. It’s been 34 years since the global community agreed to the Montreal Protocol, which banned ozone depleting substances.

https://www.youtube.com/watch?v=zqRhRPLsDsM


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