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Review
In March 2024, the Arctic ozone hole, a problem that has long plagued the scientific community and the global ecology, took a striking turn – and suddenly began to be repaired.
This phenomenon quickly attracted the urgent attention of United States experts, and the world's attention was also focused on it. Why did the Arctic ozone hole suddenly start to be repaired? Is this a good thing?
The ozone layer and the hole
The ozone layer is a relatively concentrated area of ozone in the Earth's atmosphere, mainly in the lower stratosphere, 10 to 50 kilometers above the ground. At about 20 to 25 kilometers, ozone levels are at their highest, and this altitude range is called the ozone layer.
The formation mechanism of the ozone layer is closely related to the absorption of solar radiation by oxygen molecules in the atmosphere. When oxygen molecules absorb the short-wave ultraviolet rays emitted by the sun, they decompose to produce oxygen atoms, which then combine with undecomposed neutral oxygen molecules to form ozone molecules.
Although the ozone layer is physically very thin, it is only about 3 millimeters thick when compressed to a standard atmospheric pressure (1.01×10⁵Pascal). However, this thin layer of ozone plays a vital role in protecting the earth's ecology.
It is almost completely able to absorb ultraviolet radiation (UV-C) with wavelengths of 200 to 280 nanometers and blocks about 90% of ultraviolet radiation (UV-B) in the wavelength range of 280 to 320 nanometers, thus effectively shielding ultraviolet rays, which pose a serious threat to life on Earth.
The formation of the ozone layer hole is due to both low temperature and human activities.
On the one hand, when the temperature in the stratosphere plummets to extremely low levels (usually at least minus 78 degrees Celsius), special clouds are created that provide an accelerated chemical environment for ozone depletion. In the Arctic, the harsh winter weather is particularly conducive to the formation of such low temperatures.
On the other hand, chlorine-containing compounds produced by human activities, such as freon, enter the stratosphere and decompose under the action of short-wave ultraviolet light to produce free chlorine atoms, which in turn triggers a chain reaction and catalyzes the decomposition of ozone. Chlorine-containing compounds are found in the refrigerants, aerosols, blowing agents and other products we use every day.
As early as 2011, scientists observed for the first time the ozone hole over the Arctic. At the time, persistent freezing weather in the Arctic high altitudes caused ozone concentrations to drop dramatically, to almost half of the standard concentration, sparking speculation in the scientific community that the first ozone hole in the Arctic may have formed.
And in 2020, the Arctic once again had a massive ozone hole, covering three times the size of Greenland, making it the largest ozone hole ever recorded in the Arctic, a discovery that has attracted deep attention from the global scientific community.
However, in March of this year, observers made a rare anomaly in the repair of the ozone hole.
What is the reason for cavity repair?
As the Arctic ozone hole emerges, ozone concentrations drop significantly. Take, for example, the situation in March 2020, when the ozone layer in a localized area over the Arctic fell to a record low of just 205 Dobson units. Once the ozone hole begins to repair, the monitoring equipment will show that the ozone concentration is gradually rising and slowly approaching normal levels.
Based on data obtained by the United States National Aeronautics and Space Administration (NASA) ozone observation team using the OMPS (Ozone Mapping Profiler Suite) on the United States-National Atmospheric Administration Suomi-NPP satellite, the monthly average value of Arctic ozone concentrations in March 2024 set a new record.
This suggests that ozone levels over the Arctic were higher during the month than in any previous March. Prior to this, ozone concentrations had fluctuated but never reached their March 2024 heights. This phenomenon means that the ozone layer over the Arctic is repairing itself.
Just as climate factors and human activities have contributed to the formation of the ozone hole, climate change and improved human activities have also contributed to the self-healing of the ozone hole.
In recent years, the climate in the Arctic has changed significantly, with rising temperatures and decreasing sea ice. These changes have an impact on atmospheric circulation and chemical reaction processes, which affect the distribution and transport of ozone.
The polar vortex contributes to the formation of the ozone hole, but when the polar vortex weakens or splits, ozone-rich air can flow into the Arctic from other regions to compensate for the loss of ozone and facilitate the repair of the hole. For example, the closure of the Arctic ozone hole in 2020 was due to the polar vortex "cracking", creating favorable conditions for ozone-rich air to return to the polar regions.
In terms of human activities, since the signing of the Montreal Protocol on Substances that Deplete the Ozone Layer, mankind has actively promoted new refrigerants without ozone depletion capacity, and phased out the first generation of refrigerants that have a destructive effect on ozone, such as freon.
As a result, the concentration of chlorine-containing compounds in the atmosphere gradually decreases, which reduces the number of chemicals that can destroy ozone and creates favorable conditions for the remediation of the ozone hole. Over time, the amount of these substances remaining in the atmosphere continues to decline, and their destructive effect on ozone gradually decreases, which in turn contributes to ozone recovery.
So is repairing the hole in the ozone layer a good thing?
A sign of great good?
Paul Newman, chief scientist for earth sciences at NASA's Goddard Space Flight Center in United States, said the increase in Arctic ozone concentrations in 2024 is a positive sign that the ozone layer in the stratosphere has the ability to heal itself.
Although ozone concentrations in the Arctic have fluctuated frequently for a long time, this change may suggest that the ozone layer is expected to recover gradually in the coming decades.
If the ozone hole recovers, it will have a very positive impact on the global climate, ecosystems and human health.
The ozone layer absorbs ultraviolet rays and reduces the heating effect of ultraviolet rays on the earth's surface. The remediation of the ozone hole means that more ozone can play this role, which is of great significance for maintaining the Earth's energy balance and the stability of the global climate.
Blocking ultraviolet radiation can reduce the degree of damage to plant DNA, reduce the chance of genetic mutations and lesions in plants, and benefit the normal growth and reproduction of plants. This plays a key role in maintaining the balance and stability of the ecosystem, ensuring that the food chain is the foundation of the food chain and provides an abundant source of food for other organisms.
As the amount of ultraviolet radiation reaching the surface decreases, so does the risk of diseases such as cataracts, skin cancer, and a suppressed immune system. At the same time, it can also create a suitable living environment for all kinds of organisms, reduce the damage of ultraviolet rays to organisms, and help protect biological diversity.
epilogue
The abrupt patching of the Arctic ozone hole is undoubtedly exciting news that allows us to see the fruits of the joint efforts of humanity and nature.
However, we must not be blindly optimistic and remain vigilant and continue to monitor changes in the ozone layer. This event reminds us that it is the responsibility of each of us to protect the planet's environment, and that it is only through global cooperation and sustained efforts that our planet can be ensured for a better place.
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