The History for the Protection of Earth’s Ozone Layer

As of August 2021, the IPCC has signaled a red code alert in terms of the climate crisis. Earth is protected by a layer of gas called ozone, which helps absorb the sun’s harmful UV radiation before it reaches earth. This one particular protective layer makes it possible for life to thrive on earth, and without it, we are exposed to various risks ranging from health to environment. 

The title of the scientific paper that Rowland and Molina wrote back in 1974.

Our fight to prevent the ozone layer from depleting has gone a long way, which can be traced back to 1974 when Sherwood Rowland and Mario Molina wrote a scientific article published under the journal Nature. In that article, they warned that human-generated CFCs are harming the ozone layer. Moreover, in 1985, British Antarctic Survey scientists found out about the recurring springtime ozone hole over Antarctica. 

Due to those findings, The 1985 Vienna Convention for the Protection of the Ozone Layer and its 1987 Montreal Protocol on Substances that Deplete the Ozone Layer were established to protect both human health and the environment that may be at risks due to ozone depletion as evident by the ozone hole. Both have achieved universal ratification with 198 Parties.

How The Montreal Protocol Helps Protect the Ozone 

The main objective of the Montreal Protocol is to protect the ozone layer by taking measures to control the production and consumption of substances that deplete it, with the ultimate objective of their complete elimination. The Montreal Protocol controls nearly 100 manufactured ozone-depleting substances (ODS), most of which are also potent greenhouse gases. 

The first and foremost substances are called chlorofluorocarbons, also abbreviated as CFCs, which are used in many appliances such as refrigerator, air conditioner, spray can, and metals and electronic cleaners. Other non-halogen gases that influence stratospheric ozone abundances are methane (CH4) and carbon dioxide (C02). Methane was emitted as a result of organic waste decomposition in landfills, whereas carbon dioxide was produced from the burning of fossil fuels and waste incineration.   

The Montreal Protocol has undergone several amendments since its first establishments, most of which are intended to add to the list of ozone-depleting substances ODS that need to be regulated. For example, The Kigali Amendment added HFCs to the list of controlled substances to protect future climate from the global emissions of these powerful greenhouse gases. The Amendment entered into force on 1 January 2019.

As of June 2020, four amendments to the Montreal Protocol – the London, Copenhagen, Montreal and Beijing amendments – have been ratified by 197 out of 198 parties. The fifth and most recent, the Kigali Amendment, has been ratified by over 118 parties.

In fact, the International Day for the Preservation of the Ozone Layer was established on 16th September by the United Nations General Assembly to commemorate the signing date of the Montreal Protocol on Substances that Deplete the Ozone Layer back in 1987.

Areas of low ozone above Antarctica. Source: NASA’s Ozone Hole Watch

The Outcome of The Montreal Protocol

As a result of the Montreal Protocol, the overall abundance of ozone-depleting substances (ODSs) in the atmosphere has been decreasing for the past two decades. If the nations of the world continue to comply with the Montreal Protocol, the decrease will continue throughout the 21st century. 

Implementation of the Montreal Protocol has led to the phase-out of 98.6% of ozone-depleting substances (ODS), or 1.75 million Ozone Depletion Potential (ODP) tonnes, globally. In addition, for the last two decades, signs that the ozone layer is recovering have been reported. For example, upper stratospheric ozone has increased by 1–3% per decade since 2000 (

The Benefits of Ozone Protection Efforts 

In terms of the climate crisis, the efforts in protecting the ozone layer have significantly contributed to slowing down climate change by avoiding an estimated 135 billion tonnes of carbon dioxide (CO2) equivalent emissions from 1990 to 2010. 

Moreover, models indicate that in the absence of the Montreal Protocol, global mean temperatures would have risen over 2°C by 2070, due to warming from ozone-depleting substances alone. 

No wonder that the Montreal Protocol and its amendments is considered one of the most successful international agreements to date. The Protocol demonstrates what the world is capable of achieving if we can just agree on a set course of action and stick to it throughout the years. 

Even so, we still have a long way to go. If we want to avoid the worst consequences of the climate crisis, which are already happening in many parts of the world, we would need to do twice better and faster. Surely, if we can heal the ozone layer, we might be able to slow down the climate crisis too, with the right amount of political will and action.  

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