Protection of the ozone layer
At the end of the 1980s, under the Montreal Protocol, governments around the world agreed to protect the earth's ozone layer by gradually eliminating substances that deplete it emitted by human activities. In Europe, the protocol is implemented through legislation at EU level which not only achieves the objectives set but also entails stricter and more ambitious measures.
Global action under the Montreal Protocol has stopped the depletion of the ozone layer allowing for its recovery, but much remains to be done to ensure a stable recovery.
The ozone layer
The ozone layer is a layer of natural gas in the stratosphere that protects humans and other living things from the sun's harmful ultraviolet (UV) radiation.
Although ozone is present in small concentrations in the atmosphere, most (about 90%) exists in the stratosphere, a layer above the earth's surface between 10 and 50 km thick. The ozone layer filters out most of the sun's harmful UV radiation and is therefore of crucial importance for life on Earth.
Reduction of the ozone layer
In the 1970s, scientists discovered that the ozone layer was shrinking.
Concentrations of ozone in the atmosphere vary naturally as a function of temperature, weather conditions, latitude and altitude, and substances produced by natural events, such as volcanic eruptions, can also affect ozone levels.
However, these natural phenomena could not explain the level of ozone depletion observed and scientific evidence showed that certain man-made chemicals were the cause. Substances that deplete the ozone layer (ODS) were mostly introduced in the 1970s in a wide range of industrial applications and consumer products, especially refrigerators, air conditioners and fire extinguishers.
The ozone hole
Ozone depletion reaches its highest levels at the south pole. It occurs mainly in late winter and early spring (August-November) and peaks usually occur in early October, when ozone is often completely destroyed in large areas.
This strong reduction creates the so-called "ozone hole", visible in the Antarctic ozone images made through satellite observations. Most years, the maximum surface area of the hole is larger than the Antarctic continent. Although ozone depletions are less radical in the northern hemisphere, significant thinning of the ozone layer has also occurred in the Arctic and even over continental Europe.
Most of the substances that deplete the ozone layer emitted by human activities remain in the stratosphere for decades: this means that restoring the ozone layer is a very time-consuming process.
The following graph illustrates the development of the (annual maximum) size of the ozone hole over the Antarctic. The hole has widened in the years following the ratification of the Montreal Protocol, due to the delayed effect of ozone-depleting substances, which remain in the stratosphere for a long period of time. Currently the maximum size of the ozone hole is decreasing.
Regarding the current state of the ozone hole, you can visit the Copernicus website
Effects of ozone depletion on humans and the environment
The depletion of the ozone layer causes an increase in UV radiation on the surface of the Earth, a phenomenon that is harmful to human health.
Adverse effects include an increase in certain types of skin cancer, cataracts and immune deficiency disorders. UV radiation also affects terrestrial and aquatic ecosystems, altering growth, food chains and biochemical cycles. Aquatic organisms just below the surface of the water, which form the basis of the food chain, are particularly affected by high levels of UV rays. UV rays also affect plant growth, thus reducing agricultural productivity.
Action to protect the ozone layer
Montreal Protocol
In 1987, to address the destruction of the ozone layer, the international community defined the Montreal Protocol on substances that deplete the ozone layer . It was the first international treaty signed by all countries of the world and is considered the greatest environmental achievement in the history of the United Nations.
The aim of the protocol is to reduce the production and consumption of ozone-depleting substances in order to reduce their content in the atmosphere and thus protect the ozone layer around the Earth.
The graph below shows the decrease in the consumption of substances that deplete the ozone layer covered by the Montreal Protocol, both globally and at the EEA-33 level (the 28 EU Member States plus Iceland, Liechtenstein, Norway, Switzerland and Turkey).
EU legislation
EU legislation on substances that deplete the ozone layer is among the most stringent and advanced in the world. Through a series of regulations, the EU has not only implemented the Montreal Protocol, but has often phased out hazardous substances faster than required.
The current EU “Ozone Regulation” ( Regulation (EC) No 1005/2009 ) contains a number of measures to ensure more ambitious targets. While the Montreal Protocol governs the manufacture of these substances and their wholesale trade , the Ozone Regulation prohibits their use in most cases (some uses are still authorized in the EU). Furthermore, it regulates not only wholesale substances but also those contained in products and equipment.
The EU Ozone Regulation also sets requirements for all imports and exports of substances that deplete the ozone layer and regulates and controls not only the substances covered by the Montreal Protocol (over 90 chemicals), but also others that they are not included (five additional chemicals, the so-called “new substances”).
To find out more, consult the section dedicated to the ozone regulation .
Impact of global action and remaining challenges
Global consumption of ozone-depleting substances has been reduced by approximately 98% since countries began to take measures under the Montreal Protocol. As a result, the atmospheric concentration of the more aggressive types of these substances is falling and the ozone layer is showing the first signs of recovery.
However, it is not expected to fully recover until the second half of the century. This is because, once released, the substances that deplete the ozone layer remain in the atmosphere for many years and continue to cause damage.
Much remains to be done to ensure the recovery of the ozone layer and mitigate the impact of substances that deplete it on the earth's climate.
Maximum extent of the ozone hole in the southern hemisphere from 1979 to 2019.
The actions needed worldwide to continue with the recovery of the ozone layer are:
ensure that the current restrictions on substances that deplete the ozone layer are properly implemented and that the global use of these substances continues to be reduced
ensure that banks of substances that deplete the ozone layer (both in terms of storage and quantities contained in equipment) are treated according to environmentally friendly criteria and are replaced with alternatives that are not harmful to the climate
prevent the misuse of permitted uses of substances for illegal purposes
reduce the use of these substances for applications that are not considered as consumption under the Montreal Protocol
ensure that no new chemicals or technologies are developed that could lead to the emergence of new threats to the ozone layer (e.g. very short-lived substances).
Relationship between substances that deplete the ozone layer and climate change
Interaction between depletion of the ozone layer and climate change
Source: GRID-Arendal
Most man-made substances that deplete the ozone layer are also very potent greenhouse gases. Some have a global warming effect up to 14,000 times greater than that of carbon dioxide (CO2), the main greenhouse gas.
Therefore, the global phase-out of ozone-depleting substances such as hydrochlorofluorocarbons (HCFCs) and chlorofluorocarbons (CFCs) has made an important contribution to the fight against climate change.
On the other hand, phasing out has led to a notable increase in the use of other types of gas, replacing substances that deplete the ozone layer in various applications. While these fluorinated gases (“F-gases”) do not damage the ozone layer, they have a major impact on global warming. As a result, parties to the Montreal Protocol agreed in 2016 to add the most common type of fluorinated gas, hydrofluorocarbons (HFCs), to the list of controlled substances
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