The Montreal Protocol was signed just over 30 years ago, but the ozone layer in the lower layers of the stratosphere remains dangerously thin, especially in the middle latitudes. Perhaps the reason lies in not fully studied chemicals.
In the 70s and 80s, the company actively discussed chlorofluorocarbons (CFCs) – these are substances that are used in refrigerators and are part of aerosols. During this period, it was found that CFCs damage the ozone layer. Overnight, created with the help of sprays hairstyles from the 80’s lost their attractiveness.
In 1987, representatives of some 200 countries signed the Montreal Protocol, which banned the use of CFC. It was planned to reduce the rate of expansion of the ozone hole over the Antarctic, and work on this was carried out in the next 10 years.
What happens 30 years after the signing of the Montreal Protocol? The ozone hole in the Antarctic has become controlled. The Montreal Protocol proved to be effective: it helped to prevent the release of about 135 billion tons of CO2 into the atmosphere from 1989 to 2013. It turned out that CFCs are greenhouse gases.
However, the authors of the study, published in the journal Atmospheric Chemistry and Physics, believe that the ozone layer in the lower layers of the stratosphere becomes thinner, especially in the middle latitudes, where most of the world’s population lives. Scientists believe that the so-called very short-lived substances (VSLS), which contain chlorine and bromine, cause damage to the ozone layer.
The lead author of the study, a specialist in atmospheric physics from the Swiss Higher Technical School in Zurich, William Bell, told Futurism that the Montreal Protocol can not be blamed for this. In 1987 VSLS was not included in the list of prohibited substances, as they were classified as substances with a very short life. Scientists did not expect that the lifetime of these substances would allow them to reach the stratosphere.
Apparently, VSLS did it all the same. Moreover, the ozone layer is affected by climate change. Bell believes that it is because of the climate that ozone disappears from the tropics. In the mid-latitudes the ozone layer has already become thinner, and people here are more exposed to ultraviolet rays.
Many questions still do not answer. Why does the ozone layer become thinner in the tropics than in the high latitudes? If the reason is in VSLS, how did they manage to penetrate the stratosphere? Finally, how to cope with this problem? It is necessary to create a new version of the Montreal Protocol, in which substances harmful to the ozone layer will fall under the ban.