The hole in Earth’s ozone layer, once considered the most feared environmental hazard facing humanity, will close completely across much of the world within two decades, thanks to decisive action by governments. to phase out substances that deplete the ozone layer. This is indicated by a new UN evaluation.
This is the conclusion of the UN-backed panel of experts, presented at the 103rd annual meeting of the American Meteorological Society.
The ozone layer that protects the Earth from ultraviolet radiation – and whose destruction has been due to the concentrations of harmful CFC gases used by certain industries – is on the way to full recovery.
If current policies are maintained, the ozone layer is expected to recover to 1980 values (before the ozone hole appeared). That recovery would occur around 2066 over Antarctica, in 2045 in the Arctic and in 2040 in the rest of the world.
A precedent for optimism
The success of the action on the ozone layer sets a precedent to motivate initiatives to also combat climate change. “Our success in phasing out ozone-depleting chemicals shows us what can and must be done, urgently, to move away from fossil fuels, reduce greenhouse gases, and therefore therefore limit the increase in temperature,” said Petteri Taalas, Secretary General of the World Meteorological Organization.
The scientific evaluation report that is made every four years on compliance with the Montreal Protocol (1989) on Substances that Deplete the Ozone confirms that almost 99% of the substances that deplete the ozone have been eliminated, which were prohibited by this international pact.
Comparison of ozone levels in the Arctic on March 29 and April 21, 2020.
The situation has been reversed
Following the alarming loss of ozone in the 1980s, the layer that protects us from ultraviolet radiation has been steadily improving as a result of the implementation of this international agreement that has helped to eliminate virtually all of these layer-depleting chemicals ozone (CFCs and HCFCs), as solvents and refrigerants in cold systems, among other applications.
The result, then, is that the Montreal Protocol has succeeded in safeguarding the ozone layer. Compliance with this agreement “has led to a remarkable recovery of the ozone layer in the upper stratosphere and a decrease in human exposure to the sun’s harmful ultraviolet (UV) rays,” says the United Nations Environment Program. Atmosphere.
However, this does not mean that there have not been annual fluctuations in the degree of recovery.
there have been oscillations
In fact, variations in the size of the Antarctic ozone hole, particularly between 2019 and 2021, were largely due to weather conditions. However, the Antarctic ozone hole has been slowly improving in area and depth since the year 2000.
The unified global response to deal with CFCs means that the Montreal agreement should be considered “the most successful environmental treaty in history and provides a stimulus for the countries of the world to come together and decide on an outcome and act on it,” according to David Fahey, a scientist with the National Oceanic and Atmospheric Administration who is the lead author of the new assessment.
Progress hasn’t always been smooth: In 2018, scientists detected a rise in CFC use, which was traced back to China and eventually remedied.
The Kigali amendment to phase out HFCs
It has been a difficult battle. Substitute products for CFCs, a group of industrial chemicals known as hydrofluorocarbons (HFCs), turned out to be greenhouse gases, requiring a new international agreement.
Indeed, the additional agreement of 2016, known as the Kigali Amendment to the Montreal Protocol, required the gradual reduction of the production and consumption of some hydrofluorocarbons (HFCs). HFCs do not directly deplete ozone, but they are powerful climate-changing gases. The scientific review panel estimated that this amendment will prevent warming of 0.3 to 0.5°C by 2100 (this does not include contributions from HFC-23 emissions).
“That ozone recovery is on track according to the latest quadrennial report is fantastic news,” said Meg Seki, executive secretary of the United Nations Environment Program’s ozone secretariat, who highlighted the importance it has had the Montreal Protocol on climate change mitigation cannot be overstated. “Over the last 35 years, the Protocol has become a true champion of the environment,” said Meg Seki,
“Assessments and reviews by the scientific review panel remain a vital component of the Protocol’s work that helps inform policy and decision makers.”
The latest assessment has been made on the basis of extensive studies, research and data compiled by experts from the World Meteorological Organization (WMO), the United Nations Environment Program (UNEP), the National Oceanic and Atmospheric Administration of USA (NOAA), the US National Aeronautics and Space Administration (NASA) and the European Commission.
On the other hand, for the first time, the aforementioned scientific evaluation panel examined the potential effects on ozone of the intentional addition of aerosols to the stratosphere, known as stratospheric aerosol injection (SAI).
This injection of aerosols has been proposed as a potential method to reduce climate warming by increasing the reflection of sunlight and attenuating warming. However, the panel cautions that the unintended consequences of SAI “could also affect stratospheric temperatures, circulation and rates of ozone production and destruction, and transport.”
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