The ozone layer is planet Earth’s line of defense against harmful ultraviolet radiation. Since the 1970s, global ozone has been deteriorating, due to man-made chemicals. Now, scientists have found that while the ozone layer is recovering at the North and South Poles, unexpected decreases in this layer of the atmosphere is preventing the same healing at lower latitudes.
Since the chemicals were banned, the ozone layer was thought to have been recovering completely. But British scientists say that the bottom part of the ozone layer, which is over the more populated regions of the Earth, is not improving. The cause is currently unknown, Phys.org reports.
Ozone forms in the stratosphere, around 10 to 50 kilometers above the troposphere – where life resides. It is produced in tropical latitudes and distributed throughout the rest of the world. A big part of this layer is in the lower portion of the stratosphere, where it absorbs much of the sun’s UV radiation. Without it, the sun would cause great damage to the DNA in plants, animals, and humans.
In the 1970s, scientists discovered that chemicals called CFCs, such as those used in aerosol and refrigeration products, were contributing to the rapid destruction of the ozone layer. In the Antarctic, a “hole” in the ozone layer even formed as a result.
The Montreal Protocol was set up in 1987 as a response to this drastic problem, phasing out CFCs. The ozone layer “hole” began patching itself, and signs pointed towards the same for lower latitudes. But despite this success, scientists have noticed that between 60 N and 60 S, the ozone layer is not recovering.
Joanna Haigh, Co-Director of the Grantham Institute for Climate Change and the Environment at Imperial College London, said,
The potential for harm in lower latitudes may actually be worse than at the poles. The decreases in ozone are less than we saw at the poles before the Montreal Protocol was enacted, but UV radiation is more intense in these regions and more people live there.
The team developed new algorithms to integrate the efforts of international teams working since 1985. They created a long-time series analysis to check on the trend of ozone decrease in the stratosphere, and are now looking into reasons why this recovery is being hampered.
The study was published in Atmospheric Chemistry and Physics.