Decoding ozone layer: From discovery to the recovery

By: Gufran Beig
Ozone is very rare in our atmosphere, averaging about 3 molecules of ozone for every ten million-air molecules. Nonetheless, atmospheric ozone plays vital roles and is crucial for sustaining life on Earth.
There is often a big confusion in the mind of people whether ozone is good or bad for us? Depending on where it resides, it can protect or harm life on Earth.Ozone is mainly found in two regions of our atmosphere.
Most ozone (about 85-90%) resides in a layer between approximately 15-50 km above us, a region called the “stratosphere“. This ozone is commonly known as the “ozone layer“. The remaining ozone is in the lower region of the atmosphere (surface to 15km), called “troposphere“.Near surface, it is destructive and can damage living systems, harmful to crop production, forest growth, and human health. It is the main ingredient of smog, presents a serious air quality problem. Hence, it is called “Bad Ozone“. Ozone in upper part (stratosphere), acts as a shield to protect us from the sun's harmful ultraviolet (UV) radiation. If ozone is depleted in this region, it will increase UV at surface resulting in increasing the incidences of skin cancer and eye cataracts, affect plants, crops, and ocean plankton. So, this ozone is a “Good Ozone“ for us.
Unfortunately , the good ozone was decreasing and the bad ozone is increasing in the air we breathe.
It is found in mid-1970s that some Human-produced chemicals known as ozonedepleting substances (ODSs) were steadily increasing in the atmospheres that are leading to depletion in Good ozone. The ozone depleting compounds contain vari ous combinations of the chemical elements chlorine, fluorine, bromine, carbon, and hydrogen, and are often described by the general term halocarbons or Chlorofluorocarbons, usually abbreviated as CFCs. Many of them are being used in refrigeration, air conditioning, foam blowing, cleaning of electronics components, and as solvents.
Two responses are natural when a new problem has been identified: Cure and prevention. When the huge volume of the atmosphere and the magnitude of global ozone depletion are carefully considered, approaches to cures quickly become much too expensive, impractical, and potentially damaging to the global environment.
Prevention involves the internationally agreed upon Montreal Protocol and its Amendments and Adjustments, which call for elimination of the production and use of the CFCs and other ozone damaging compounds so that they can be phased out and ozone starts to recover. To stop ozone depletion and check the growing use of ODSs, the governments of the world, under the United Nations, crafted a protocol on September 16, 1987 known as “Montreal Protocol“. This day , September 16, is celebrated as the World Ozone Day since then.
The discovery , understanding, decisions, actions, and verification under this protocol yielded notable achievements and progress conveyed to world through a report, published every 4 year. The latest news from scientists and report from the UNEP and WMO came through an exercise involving 300 scientists across the world. The most striking finding of this report is that the ozone layer is in the path of recovery and likely to be fully recovered by 2050.
Without the Montreal Protocol, atmospheric levels of ozone depleting substances could have increased tenfold by 2050.The protocol will prevent 2 million cases of skin cancer annually by 2030, averted damage to human eyes and immune systems, and protected wildlife and agriculture.
The news for tropics including India for present period is good but not so good for the future, which is intrinsically linked to climate change. Human activities will continue to change the composition of the atmosphere but we need to be environmentally disciplined.
We have achieved a success story that ozone layer is showing signs of recovery .The Montreal Protocol -one of the world's most successful environmental treaties -has protected the stratospheric ozone layer and avoided enhanced UV radiation reaching to us. Ozone success story written by many -scientists, technologists, economists, legal experts, and policymakers where continuous healthy dialogue has been a key ingredient. However, there are challenges. The ozone success story should boost our moral to display the same level of urgency and unity to meet challenge of climate change.
(The writer is project director, SAFAR, member , review panel of United Nations Environment Programme and World Meteorological Organization)