A team of experts supported by the United Nations recently released a report stating that the ozone layer, which protects the earth from short-wave ultraviolet rays, is expected to gradually recover within 40 years, and the huge “ozone hole” over Antarctica will also be filled.
But scientists say the recovery of the ozone layer is a gradual process that will take many years. If current policies remain unchanged, the ozone layer is expected to return to 1980 levels by 2040, before the “ozone hole” appeared, the report said. In 2045, the Arctic ozone layer is expected to return to normal levels. The Antarctic ozone layer may return to normal by 2066.
The scientific assessment report is completed every four years by researchers from the World Meteorological Organization, the United Nations Environment Programme, the United States National Oceanic and Atmospheric Administration, NASA and the European Commission. The review follows the signing of the 1987 Montreal Protocol, which bans the production and consumption of chemicals that erode the Earth’s ozone layer.
Steady decline in banned chemicals
The ozone layer in the upper atmosphere protects the planet from the sun’s ultraviolet radiation, which has been linked to skin cancer, eye cataracts, compromised immune systems and the destruction of farmland.
Scientists and environmental groups have long hailed the global ban on ozone-depleting chemicals as one of the most critical environmental achievements to date and one that could set the precedent for broader regulation of climate-warming greenhouse gas emissions.
”Action to protect the ozone layer sets a precedent for action to protect the climate,” WMO Secretary-General Petteri Taalas said in a statement. “Our success in phasing out ozone-depleting chemicals shows that We too can and must do something to wean ourselves off fossil fuels and reduce greenhouse gas emissions, thereby limiting temperature rise.”
Global emissions of banned chemical CFC-11 rise after years of unexpected increases, say scientists , has been steadily declining since 2018. The report also found that the ozone-depleting chemical chlorine in the stratosphere has fallen by 11.5 percent since its peak in 1993, while bromine has fallen by 14.5 percent since its peak in 1999.
But scientists have warned that efforts to artificially cool the planet by injecting aerosols into the upper atmosphere to reflect sunlight could dilute the ozone layer. At the same time, further research is needed on the implications of emerging technologies such as geoengineering.
Where did ozone come from?
It was more than 150 years ago that humans really knew ozone. Dr. Schanbein of Germany first proposed that the odor produced in water electrolysis and spark discharge was the same as that produced after lightning in nature. Dr. Schanbein believed that the odor was difficult smell, hence the name ozone. The ozone layer was discovered by French scientist Fabry in the early 20th century. In 1930, the British geophysicist Kapman proposed that the ozone in the atmosphere is mainly produced by the three-body collision between oxygen atoms and oxygen molecules with the participation of a third neutral molecule. At an altitude of more than 60 kilometers, the sun’s ultraviolet rays are strong, a large number of oxygen molecules are dissociated, the chance of three-body collision is reduced, and the ozone content is extremely small. At a low altitude below 5 kilometers, the ultraviolet rays are greatly weakened, and there are few oxygen atoms, making it difficult to form ozone. Within the altitude range of 20-25 kilometers, there are enough oxygen atoms and enough oxygen molecules, which is most conducive to the three-body collision, and the formation of ozone is about 50 billion tons per year.
Ozone that forms in nature is mostly distributed in the atmosphere 20Km to 50Km above the ground, which we call the ozone layer. Ozone in the ozone layer is mainly produced by ultraviolet rays. Ultraviolet rays in the sun’s rays are divided into long-wave and short-wave. When oxygen molecules in the atmosphere (21%) are irradiated by short-wave ultraviolet rays, the oxygen molecules will decompose into atomic states. Oxygen atoms are extremely unstable and easily react with other substances. Such as reacting with hydrogen (H2) to generate water (H2O), and reacting with carbon (C) to generate carbon dioxide (CO2). Similarly, when reacted with molecular oxygen (O2), ozone (O3) is formed. After ozone is formed, because its specific gravity is greater than that of oxygen, it will gradually fall to the bottom of the ozone layer. During the falling process, with the change (increase) of temperature, the instability of ozone becomes more and more obvious, and then it is irradiated by long-wave ultraviolet rays, and it is reduced to oxygen. The ozone layer keeps the dynamic balance of this oxygen and ozone conversion.
Ozone is not evenly distributed
Time and space changes The total amount of ozone in the earth’s atmosphere has obvious time and space changes: it is the lowest near the equator and the highest near the latitude of 60°; any region is the largest in spring and the smallest in autumn; the ozone content in a day is usually higher at night than during the day; in Asia In the latitude zone, when the Siberian air mass invades, the total amount of ozone increases obviously, but when the equatorial air mass comes, the total amount of ozone decreases. About 1% of the sun’s ultraviolet rays reach the ground. Especially in the forests, mountains, and coasts where the air pollution is relatively light, there are more ultraviolet rays, and there is relatively abundant ozone.
Depletion of the ozone layer can lead to abnormal weather
Last year, the International Department of China Biodiversity Conservation and Green Development Foundation (referred to as China Green Hair Association, Green Association) learned from a world-renowned journal an article “The depletion of the ozone layer will lead to abnormal weather”. The climate has a serious impact.
Researchers at ETH Zurich in Switzerland studied the impact of ozone depletion on climate in the northern hemisphere by analyzing data from the past 40 years and concluded that in years with severe ozone depletion in the spring, warmer and drier conditions emerge in southern Europe and Eurasia a few weeks later. , a large amount of precipitation occurred in Northern Europe.
”The destruction of ozone can only occur when it is cold enough and the polar vortex in the stratosphere is strong,” said the authors of the paper. Ozone normally absorbs ultraviolet radiation from the sun. This warms the stratosphere and helps distort the polar vortex in spring. But if the ozone decreases, the stratosphere cools down and the vortex remains solid. The long-term presence of the polar vortex could explain the observed temperature and precipitation anomalies, the researchers said.
Ozone Monitoring Tools – Satellite Remote Sensing
Ozone layer monitoring refers to the monitoring and observation of the ozone layer in the stratosphere and its changes by means of satellite remote sensing.
Remote sensing technology Remote sensing is also called RS, it is one of the important components of “3s” technology, this technology belongs to the category of marginal science, as a detection technology, RS has the characteristics of advanced and practical, because In this way, it has been widely used in many fields.
The application of aerial photography is the basis of RS technology. It first appeared in the early 1960s. At that time, this technology was called aerial remote sensing. When the first land satellite was successfully launched into the sky, the era of space remote sensing officially opened. Since the emergence of RS technology, it has experienced 50 years of development. Today, RS technology is very mature and has been applied in many fields, such as agriculture, forestry, hydrology, meteorology, environmental protection, and national defense.