By Raunak Haldipur
We have learnt since our school-days that we must protect our environment and keep the earth green to protect the Ozone layer else we’ll all be exposed to the Sun’s ultraviolet rays. Ever since the ozone hole above Antarctica was discovered, all the countries in the world have taken the ozone layer depletion and climate change really seriously. Post the Montreal protocol, we are seeing the ozone layer healing.
The evidence
The Montreal Protocol has been a great success at banning the production of ozone-depleting substances. Dr Susan Strahan, an atmospheric scientist at NASA’s Goddard Space Flight Center and her team have been measuring those substances at the earth’s surface since the 1980s. She says that before the Montreal protocol, ozone-depleting substances were going up rapidly. Once the protocol was signed and the regulations went into effect, the levels of these substances have come down drastically. The chlorine that is released from the Chlorofluorocarbons (CFCs) is actually what destroys the ozone. However, they have to get up and break down high up into the stratosphere for them to be able to destroy the ozone.
Looking at how much ozone depletion is going on at the same time is also vital because ozone levels can vary for a lot of different reasons. For example, when it is warm, there is more ozone depletion that when it is cold. Previous satellite observations have observed changes in the size of the ozone hole, noting that it can grow and shrink from year to year. The new study is the first to directly measure changes in the amount of chlorine, the main CFC byproduct responsible for ozone depletion in the atmosphere above Antarctica, according to a statement from NASA. The study showed a 20 percent decrease in ozone depletion due to chlorine between 2005 and 2016.
Details of the study
The new study looked at ozone data collected between 2005 and 2016 by the Microwave Limb Sounder (MLS) instrument which is aboard the Aura satellite. The instrument cannot directly detect chlorine atoms, but instead detects hydrochloric acid, which forms when chlorine atoms react with methane, and then bond with hydrogen. When Antarctica is exposed to sunlight during summer, the CFCs break down and produce chlorine, which then breaks apart the ozone atoms. But during the winter months (early July to mid-September), the chlorine tends to bind with methane once all the ozone has been destroyed in its vicinity.
“By around mid-October, all the chlorine compounds are conveniently converted into one gas, so by measuring hydrochloric acid, we have a good measurement of the total chlorine,” lead study author Susan Strahan said.
Are human activities actually restoring the ozone?
Humans are still continuing to exploit the environment. This is inevitable due to the growing global population. The Montreal Protocol and the Kyoto Protocol are considered to be one of the most successful treaties signed and ratified by 197 parties, which makes them the first universally ratified treaties in the history of the United Nations. The Montreal protocol has gone through many revisions, the latest being in 2016, which is yet to be put into effect.
Featured Image Source: Pixabay
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