International Day for the Preservation of the Ozone Layer

Montreal Protocol@35:
Global cooperation protecting life on Earth

Sun is the saviour of life on planet earth. If all the sunlight with its intensity falls on the surface of Earth, it would be difficult for the life systems to cope. Ozone comes to the rescue here and protects from harmful ultraviolet rays from the Sun. Ozone is a molecule present in the gaseous form consisting of three oxygen atoms and is present in traces in the atmosphere. It surrounds the planet earth as a layer. Ozone molecules are continually being destroyed and reformed naturally. It is noticed that it is getting thinner due to more ways of losing ozone. Some of them are catalytic. Hydroxyl and NOx radicals and chlorine atoms from chlorofluorocarbon react with ozone, resulting in ozone depletion. The tricky part is that such reactions make the reformation of ozone difficult.

The reduction in the ozone content is often referred to as the ozone hole. It is not a hole, but the ozone layer is becoming thinner. Noticing the ozone layer depletion led to the international community coming together and establishing an action plan for its protection. It followed the drafting of “The Montreal Protocol on Substances that Deplete the Ozone Layer” in September 1987. In 1994, the UN proclaimed 16 September as the International Day for preserving the Ozone Layer to commemorate the date of the signing of the Montreal Protocol. The ozone layer is healing. The nature of the gases responsible for ozone depletion leaves the impact likely to continue for a more extended period. If all goes according to plan, the Earth could restore the ozone layer to its 1980s level by 2050. The Montreal Protocol’s success proves that if humanity comes together and plays its part in protecting the environment, the environment, in turn, heals and saves humanity. It shows that collective decisions and actions, guided by science, are the only way to solve major global crises.

The Montreal Protocol and the Kigali Amendment show us that by acting together, anything is possible. So let us act now to slow climate change, feed the world’s hungry and protect the planet that we all depend on.
António Guterres, UN Secretary General

Sun is the saviour of life on planet earth and provides the crucial ingredient for photosynthesis in food production and life systems. If all the sunlight with its intensity falls on the surface of Earth, it would be difficult for the life systems to cope. Ozone comes here to the rescue and protects from harmful ultraviolet rays from the Sun.

Ozone is a molecule in the gaseous form consisting of three oxygen atoms. In the atmosphere, it is present in traces (~ three molecules for every ten million air molecules). It surrounds the planet as a layer and contains approximately ten parts per million of ozone. About 90% of the ozone in the atmosphere is held in the stratosphere. The stratosphere is the mass of protective gases surrounding the planet, approximately 50 Kilometers above the Earth’s surface. Ozone molecules are continually being destroyed and reformed naturally. It is noticed that it is getting thinner and thinner, as there are more ways of losing ozone emerging. Some of them are catalytic. Hydroxyl and NOx radicals, chlorine atoms from chlorofluorocarbon, react with ozone, resulting in ozone depletion. The tricky part is that such reactions make the reformation of ozone difficult. The reduction in the ozone content leads to reduced absorption of ultraviolet radiation. It is reported that by 1970, ozone levels had dropped by an average of about 4%. The reduction in the ozone content is often referred to as the ozone hole. They are not holes but the ozone layer, which is becoming thinner (more prominently seen in Antarctica). The depletion affects life on Earth, the destruction of plants and ecosystems, an increase in skin cancer, etc.

While measuring radiation from the Sun’s surface, French physicists Charles Fabry and Henri Buisson discovered the ozone layer in 1913. Sydney Chapman, a British physicist, discovered the photochemical mechanisms that resulted in the formation of the ozone layer in 1930. The ozone reaction with oxygen results in the generation of heat. As one moves away from Earth, temperature decreases, but when it comes to the stratosphere, a temperature reversal is seen due to the heat generated due to ozone and oxygen interaction. The work on understanding ozone formation and decomposition in the stratosphere led Mario Molina and Sherwood Rowland to win the Nobel Prize in Chemistry (in 1995). The discovery of the annual depletion of ozone above the Antarctic is the result of the work done by Joe Farman, Brian Gardiner, and Jonathan Shanklin (reported in a paper published in nature). Astronomical researchers said that Venus and Mars are the other planets where a thin ozone layer was observed.

Noticing the ozone layer depletion led to the international community coming together, establishing an action plan for its protection, and formalising it in the Vienna Convention in March 1985. It followed the drafting of The Montreal Protocol on Substances that Deplete the Ozone Layer in September 1987. The protocol aims to eliminate the chemical substances causing ozone depletion based on the knowledge acquired through science and technology. To commemorate the date of the signing of the Montreal Protocol. In 1994, the UN proclaimed 16 September as the International Day for preserving the Ozone Layer. By 2009 it had become the first treaty in UN history to achieve universal ratification. This year’s observation celebrates 35 years of the Vienna Convention and global ozone layer protection. It is a celebration of coming together of the world’s governments for the environment and ending one of the biggest threats to humanity, the depletion of the ozone layer. Kigali’s Amendment in 2016 led to the agreement to phase-down hydrofluorocarbons (HFCs). There are still a few exceptions for essential uses where no acceptable substitutes have been found, like metered dose inhalers commonly used to treat asthma and other respiratory problems or halon fire-suppression systems used in submarines and aircraft. Let us hope that research will lead to replacing them sooner.

The ozone layer is healing. The closure of the hole in the ozone layer is seen. The nature of the gases responsible for ozone depletion leaves their impact to continue for a more extended period. If all goes according to plan, the Earth could restore the ozone layer to its 1980s level by 2050.

The Montreal Protocol’s success proves that if humanity comes together and plays its part in protecting the environment, the environment, in turn, heals and saves humanity. It shows that collective decisions and actions, guided by science, are the only way to solve major global crises.