Positive changes in the environment are highly possible when humans come together to take action. That’s what happened to the hole on the Earth’s ozone layer, which has been found to be shrinking since the 1980s after nations agreed to ban the use of chlorofluorocarbons (CFCs), or chemicals that deplete the ozone layer.
NASA has confirmed that the ozone hole above the Antarctic is starting to close up ever since the ban was imposed through the 1987 Montreal Protocol. Data from NASA’s Aura satellite showed the success of the ban, with 20 percent less depletion of the ozone layer since 2005. In the study published in Geophysical Research Letters, chlorine levels were found to have declined by 0.8 percent each year from 2005 to 2016.
There have been previous studies conducted to analyze the changes in the size of the ozone hole to prove that there is less depletion in the layer. But this latest study, which was spearheaded by lead author Susan Strahan, was the first to look at the chemical composition inside the hole, confirming that ozone depletion has not only decreased but also that this decrease was a result of lowered levels of CFCs.
CFCs are chemicals abundant in aerosol sprays, refrigerants, and blowing agents. The radiation from the UV rays of the sun breaks down CFCs into chlorine, which will then slowly destroy the ozone layer. To arrive at their findings, the researchers used data from Microwave Limb Sounder (MLS) on the Aura satellite since 2005, which showed the levels of hydrochloric acid in the ozone layer.
Hydrochloric acid is produced when chlorine has already damaged the layer. By knowing the levels of hydrochloric acid, scientists can get a measurement of just how much chlorine is present. After comparing levels of hydrochloric acid and nitrous oxide — another gas that behaves like CFCs — it was found out that the chlorine levels were going down by 0.8 each year, on average.
With the findings, Strahan was positive that the ozone depletion was directly caused by the decline in CFCs. As to how this translates to the future of the ozone layer, co-author Anne Douglass said that the ozone layer can recover, but it can take decades.
“As far as the ozone hole being gone, we’re looking at 2060 or 2080. And even then there might still be a small hole.”