New measurements, as a part of the conducted research, show that due to a depletion of the chemical that can damage the ozone layer, called chlorofluorocarbons (CFCs), the ozone layer hole is slowly healing. The research has been conducted by NASA’s Goddard Space Flight Center and was published on Jan. 4 in the Geophysical Research Letters.
The report published on NASA’s site reveals that the measurements taken during the research reveals a decrease in chlorine chemicals in the layer, which is a direct result of an international ban on man-made chemicals which contain chlorine over the years. The international ban on those chemicals resulted in a 20% decrease in ozone depletion during the winter of 2016, as opposed to the 2005 statistics gathered by the satellite Aurora of NASA.
One of the researchers who conducted the study and atmospheric scientist, Susan Strahan, said on NASA’s website, “We see very clearly that chlorine from CFCs is going down in the ozone hole, and that less ozone depletion is occurring because of it.”
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According to the report, at the time when the process of ozone depletion is active, chlorine can be found in different molecular forms, of which most are not measured. After chlorine destroys the ozone particles in the layer, it then reacts with methane which forms hydrochloric acid, which can be measured by the Microwave Lim Sounder (MLS) located in the Aura satellite.
“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,” Strahan added.
According to the report there is nitrous oxide in the stratosphere, and it has a similar behavior to the CFC substances. Although CFCs were decreasing at the surface, nitrous oxide wasn’t. That would mean that if there was less CFCs in the stratosphere, there would be less chlorine measured for the value of nitrous oxide, according to the report. According to the measurement by the MLS, it has been determined that the overall level of chlorine has been decreasing at a rate of 0.8% per year. There has been an expected 20% decline in ozone depletion through the winter months between 2005 and 2016, the report states.
“This is very close to what our model predicts we should see for this amount of chlorine decline,” Strahan said. “This gives us confidence that the decrease in ozone depletion through mid-September shown by MLS data is due to declining levels of chlorine coming from CFCs. But we’re not yet seeing a clear decrease in the size of the ozone hole because that’s controlled mainly by temperature after mid-September, which varies a lot from year to year,” she added.
According to a report by Ars Technica, during the 1970s and 1980s there had been evidence that the ozone layer hole had been spreading as a result of the CFC substances, which resulted in the ozone layer hole over Antarctic, causing nations and companies to take action.
Many companies began looking for alternative to CFCs, while the nations made an agreement to try to limit the use of chemicals which could damage the ozone layer. The agreement they made was known as The Montreal Protocol.
According to the report, it was very challenging to determine whether the protocol had a positive effect on the ozone layer hole or not, because ozone is slowly naturally generated in the stratosphere, and the level of its eradication changes at times. The ozone layer recovery has been said to be so slow that some people believed that the whole story was a scam or conspiracy theory. Nevertheless, the research showed that the Montreal protocol had a positive impact on the ozone hole.