The ozone layer is all that stands between us humans on Earth and UV radiation – and it’s not exactly abundant.
the United Nations put it in a nutshell: “If we could bring the entire ozone layer to sea level, it would only be three millimeters thick. It is exactly what protects us from dangerous ultraviolet radiation.”
In some areas of the stratosphere, the ozone is so low that one speaks of the ozone hole. We’ve known for a while that the ozone layer is under threat and needs our protection.
The United Nations has also been working for more than three decades to reduce the ozone hole and to repair it as much as possible. This is enshrined in international treaties such as the Montreal Protocol. It deals with substances that are responsible for the depletion of the ozone layer.
According to meteorologists from US National Oceanic and Atmospheric Administration By early 2022, the amount of substances that deplete ozone in our stratosphere had fallen by 50 percent, back to where it was before the ozone hole became a problem. But there is still a long way to go before the ozone layer is restored to some extent.
What is the ozone layer?
Ozone is a molecule made up of three oxygen atoms (O3). Ozone molecules, which form a layer of gas, naturally occur in the upper atmosphere, also known as the stratosphere. This layer of gas protects life on Earth by filtering some of the sun’s ultraviolet radiation.
The Rhone Glacier in Valais, Switzerland, is partially covered with tarps to prevent melting
Ozone is also formed by chemical reactions between pollutants in the air and other emissions in the lower atmosphere, called the troposphere. While ozone provides us with a protective shield in the stratosphere, direct contact in the troposphere can be hazardous to plants, animals and humans.
Where exactly is the problem?
It is often said that we need the ozone layer because it prevents UV radiation from “sterilizing” the earth’s surface. We know that sunbeams have this power. Just think what it’s like to let our laundry dry outside on a hot summer’s day. It’s almost sterilized. But UV radiation can also be deadly.
There are three types of UV radiation: A, B and C.
The ozone layer and the atmosphere absorb UVC radiation – the most energetic form of UV radiation – and also some UVB radiation. UVA, on the other hand, is not absorbed by the ozone layer and reaches the earth’s surface in its entirety.
We humans need UVB radiation to produce vitamin D. That’s good for us in reasonable amounts. However, too much UVB and UVA radiation can lead to serious diseases such as skin cancer, cataracts, suppression of the immune system and premature aging of the skin. Excess UV radiation is also associated with reduced crop yields and negative impacts on the marine food chain.
What Causes the Depletion of the Ozone Layer?
We humans are largely responsible for ozone depletion because we use ozone-depleting substances (ODS). Gases such as CFCs, halons, CH3CCl3 (methyl chloroform), CCI4 (carbon tetrachloride), hydrochlorofluorocarbons (HCFCs) and methyl bromide deplete the ozone layer.
These substances are found in refrigerators, air conditioners, aerosols, solvents, pesticides and the like. They release chlorine and bromine atoms into the stratosphere, which in turn break down ozone molecules.
Scientists warn that “very short lived substances” (VSLS) also pose a threat to the ozone layer. For example, VSLSs are found in marine life, algae, and phytoplankton.
Is the ozone hole really a big hole?
Strictly speaking, there is no ozone “hole”, but rather a region of exceptionally low ozone levels over Antarctica. There is also talk of a “dramatic thinning out” of the ozone. It occurs in spring in the southern hemisphere, ie from August to October, and there are also “mini-holes” and other deviations in the northern hemisphere.
One of the largest and deepest ozone holes of the past 15 years lies over Antarctica
Will the ozone layer ever fully recover?
According to researchers, the future looks bright for the ozone layer. It could recover over the next 50 years – probably between 2050 and 2065 – and reach pre-1980 levels. To do this, however, we must meet the goals set out in international treaties.
The Vienna Convention and the Montreal Protocol for example, September 16, 2009 became the first treaties in the history of the United Nations to be universally ratified. September 16 is now commonly known as World Ozone Day or the International Day for the Conservation of the Ozone Layer.
Of the NASA Ozone Watch provides daily updates including images and animations from 1979 to 2022.
Adapted from the English by Gudrun Heise.
