LONDON: The big ozone hole in Earth’s atmosphere has started shrinking and will effectively disappear by the end of this century, says a new study conducted by NASA. The study also suggests that the size of ozone holes, currently 12 million square miles, will reduce to less than 8 million square miles over a period of next 30 years.
The ozone hole was once the biggest environmental issue for environmentalists and scientists. The hole was first discovered by a group of British scientists about 30 years ago, while they were on a mission to Antarctica. At that time, it was suggested that the ozone hole – formed over southern pole due to widespread use of damaging chemicals – would result in increased levels of cancer-causing ultraviolet radiations on Earth.
In 1987, all major economic powers of the world agreed to Montreal Protocol with the aim to reduce widespread use of harmful chemicals, including chlorofluorocarbons, which were causing damage to ozone layer. After 1987, most ozone-damaging chemicals were replaced by ozone-friendly alternative chemicals.
In the stratosphere, ozone is formed when high-energy ultraviolet rays strike oxygen molecules (O2) and split them into two single oxygen atoms (O). A reaction between an O2 molecule and a free oxygen atom forms a molecule of ozone (O3).
Ozone is important for human life as it is capable of absorbing harmful ultraviolet solar radiations. An ozone molecule after absorbing low-energy ultraviolet radiation splits into an O2 molecule and a free oxygen atom. The oxygen atom again reacts with an O2 molecule to form an ozone molecule. This ‘ozone-oxygen cycle’ means ultraviolet radiations are continuously converted into heat in the atmosphere.
The impact of Montreal Protocol on the size of the ozone hole was not very much clear until now. In its ozone study, Goddard Space Flight Centre of NASA used the data sent by its AURA satellite, and with this data, it was possible to get specific details about long-term trends in ozone depletion.
According to Goddard Space Flight Centre report, ozone holes are constantly shrinking, and over the next 25-30 years, they will no longer be a major concern for environmentalists. The current readings reveal that ozone hole size is now smaller than what it was in the 1960s.
An alarming result from NASA’s latest study is that the airborne CO2 levels on Earth are now above 400 parts per million (ppm), about 50 ppm above what is believed to be a safe level for humans. This alarming figure also suggests that we humans are two full years ahead of schedule.
