Short history of the Montreal Protocol and holes in the ozone layer

By Sandor Alejandro Gerendas-Kiss
Published on October 19, 2018




The discovery of the holes in the ozone layer and how the problem was addressed by the Montreal Protocol is a clear example of how research and scientific discoveries about climatic and environmental anomalies can be discussed and resolved successfully by nations through agreements, treaties and protocols, when there is consensus and the will to do so.

However, the compliance and final success of the agreements depends on humans, but above all on the countries, their governments and businessmen. Control and supervision are essential, but if they do not work locally, there is the resource of observation by scientists and specialists through the resources available to science and high technology. We must recognize to NASA the constant monitoring of the atmosphere, and in this case of the ozone layer, crucial to know the state of the matter.

For the ozone layer to recover it is necessary that the Montreal Protocol is met. We say this because something has recently been detected that does not work as agreed. “For six years, the decrease in the presence of chlorofluorocarbons in the atmosphere had slowed by 50%.” There are already some indications of some factors that cause it, but there are still others to be discovered, especially the places where illegal emissions come from.

The Montreal Protocol banned the use of chlorofluorocarbons (CFCs), after it was found that the colorless gas caused significant damage to the ozone layer. This molecule is released mainly by refrigeration systems, such as refrigerators and air conditioners and by aerosols.

In large part CFCs were replaced by hydrochlorofluorocarbons (HCFCs), which also damage the ozone layer, although its effect is almost 20 times lower. That is why HCFC is a transient replacement until a completely clean method is achieved in the future.

The ozone layer is the natural filter of our planet that protects us from the powerful ultraviolet (UV) rays. With your help you reduce the risk of skin cancer or cataracts, among other diseases. That is why it is so important that the agreements of the Montreal Protocol are complied with it.

NASA claims that, if the Montreal Protocol had not been signed, two thirds of the ozone layer would have been destroyed. UV radiation, which damages DNA, would have increased six times. Barely five minutes of sun exposure would have caused skin burns.

The hole in the ozone layer is an area of the Earth’s atmosphere that produces abnormal reductions in the ozone layer. It is an annual phenomenon observed during the spring in the polar regions and that is followed by a recovery during the summer.

The southern hemisphere of the Earth is the most affected by the problem of ozone holes, located largely on the Antarctic. In South America, Chile and Argentina are the two most vulnerable countries.

Montreal Protocol Timeline

1974. Frank Sherwood Rowland, American scientist, and his collaborator Mario Molina, Mexican scientist, were the first to demonstrate that chlorofluorocarbons (CFCs) used in cooling systems and as atomizer propellants, were lethal to the ozone layer that protects Life on earth. In 1995 they would share the Nobel Prize in Chemistry with the Dutchman Paul Crutzen.

1974. Rowland and Molina testify their findings before a hearing of the House of Representatives of the United States in the month of December.

1976. The National Academy of Sciences of the United States publishes a report that validates the results and gives credibility to the Molina and Rowland hypothesis.

1980. During the 1980s, DuPont, the world’s largest CFC producer, unsuccessfully tries to convince the US government, and the general public, that CFCs are not responsible for the depletion of the ozone layer.

1985. On May 16 Joseph Farman, Brian Gardiner and John Shanklin, who worked for the British Antarctic service, shake the world by publishing in the journal Nature an article documenting how the ozone layer, located on the Antarctic continent, was reducing faster than anticipated. Two years later the Montreal Protocol would be signed, an agreement that prohibits the use of (CFC).

1987. Representatives of 43 nations sign the Montreal Protocol. They are committed to maintaining the CFC production levels of 1986 and reducing them by 50% in 1999.

1989. The Montreal Protocol enters into force on January 1.

1990. As more scientific evidence accumulates about the human origin of the increase or decrease of ozone in the atmosphere, a new agreement was signed in 1990 in London. Participants commit to eliminate totally CFCs in the year 2000. Only a small percentage marked as essential use is allowed, such as inhalers for asthma cases.

1992. A new meeting in Copenhagen advances the date of CFC phase-out for 1996. That wishes in later years it would be shown that they were too optimistic.

1992-1999. The document of the Montreal Protocol was revised several times: 1991, Nairobi; 1992, Copenhagen; 1993, Bangkok; 1995, Vienna; 1997, Montreal and in 1999, Beijing.

1995. The twelve countries of the European Community prohibit, as of January 1, 1995, the use of CFCs, which are replaced by HCFCs temporarily, being 20 times less destructive than the CFC, until finding a definitive substitute.

2001. In a report, NASA finds that the weakening of ozone over Antarctica had remained the same as in the previous three years.

2003. The ozone hole reaches its second largest extension in history.

2006. The use of CFCs worldwide is prohibited. This year’s scientific evaluation states that “The Montreal Protocol is working. There are clear signs of a decrease in the presence of ozone-depleting substances and some early signs of a recovery of stratospheric ozone. ”

2013. The Parties to the Protocol have agreed this year as the limit to set production levels for HCFCs and agreed to start the reduction process from 2015.

2017. On June 28, BBC Mundo Ciencia, headlined: “The chemical that puts the ozone layer back in danger”. Against all odds, it says: “The recovery of the ozone layer could take several decades longer than expected if the increasing emissions of dichloromethane, a chemical used as a paint thinner and to prepare chemical compounds for refrigerators and air conditioners, are not slowed down, revealed a new investigation. However, dichloromethane – also known as methylene chloride – was not included in the Protocol, because it has a short life (that is, it breaks down after about five months). However, it releases chlorine that can destroy ozone if it reaches the ozone layer in the stratosphere. ” According to a study published in the journal Nature Communications, dichloromethane levels in the atmosphere increased by 8% per year between 2004 and 2014. Considering these new data, some scientists recalculated the closing times of the holes for 2065 -2095.

2018. In May of this year, a study led by Stephen Motzka, chemical researcher at NOAA, the National Oceanic and Atmospheric Administration of the United States, “reported that somewhere in Asia, emissions of banned chemicals that deteriorate the ozone layer are being generated.” “A few months later, the Environmental Research Agency (EIA), based in the United Kingdom, said that these gases could come from polyurethane foam insulation for domestic use produced in China at a reduced price, although it is still being investigated.”

As we said at the beginning, for the ozone layer to recover it is necessary that the Protocol is strictly complied with. It is urgent to determine the origin of the anomaly and resume the good path of Montreal.

All these climate-related issues would be easier to solve if more people put to focus on these problems. The good news is that this happened earlier this month, during the presentation of the Fifth IPCC Report, held in Incheon, South Korea, which warned of the dangers if global warming is not curbed.

This meeting had the merit of obtaining headlines in many media around the world, only comparable with the announcement of the approval of the Paris Agreement in 2015. In the networks and in the websites, the number of people who entered to search information and comment on the subject.

Undoubtedly, progress has been made in this area, but we must continue to fight to capture the interest of the great public.



The Telegraph. Hole in ozone layer has shrunk thanks to worldwide ban of CFCs, Nasa confirms. Retrieve from

Wikipedia. Montreal Protocol. Retrieve from

BBC. Mysterious rise in emissions of ozone-damaging chemical. Retrieve from

UPI. NOAA reports rising concentration of ozone-eating CFCs. Retrieve from



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