The Shrinking Ozone Hole, A Sign Of Relief For Environmentalists

Highlights:

• NASA's Aura satellite shows that the ozone hole over Antarctica is gradually reducing in size.
• There was 20 percent less ozone depletion in 2016 compared to the depletion levels 9 years before.
• The achievement is a result of the ban on chlorofluorocarbons which was adopted by several nations according to the Montreal Protocol.

The earth orbiting Aura satellite of NASA has calculated a twenty percent less ozone depletion in 2016 compared to the depletion levels nine years before, when the chlorine and ozone measurements were first taken. The study data is published in the journal Geophysical Research Letters. The decline in chlorine levels resulting from the international ban on chlorofluorocarbons has led to the decrease in size of the atmospheric ozone hole.

When it comes to bad news about climate change, there is never a shortage. From air pollution to rising global temperatures, there has never been positive news and the solutions have always seemed farfetched. But mankind has achieved a major feat by solving a huge environmental problem—the ozone hole.

Chlorofluorocarbons and the Ozone Hole

Chlorofluorocarbons or CFCs were one of the common compounds back in the 1980s to be used in aerosol sprays, refrigerants, solvents, and other products. In the upper layer of the atmosphere chlorine containing CFCs break down to produce inorganic chlorine which further breaks down the protective ozone layer that protects the earth from the sun's harmful radiations. One CFC molecule can destroy 100,000 ozone molecules and their long life span means that they could persist in the atmosphere for decades.

Recovery of the Ozone Hole

NASA's satellite data suggests that the ozone hole over Antarctica is slowly reducing in size. According to the Montreal protocol, ozone recovery requires two things to happen:

• Chlorine levels in Antarctica need to decline
• There needs to be a reduction in ozone depletion as a result of chlorine decline

By measuring O₃, HCl, and N₂O, Aura Microwave Limb Sounder demonstrated that inorganic chlorine from 2013 to 2016 was 223 ± 93 parts per trillion lower in the Antarctic atmosphere than during the years 2004 to 2007. This brings the 9 year annual rate of inorganic chlorine decline to 25 ± 10 ppt/yr (~0.8%/yr). The study also observed a reduction in ozone depletion in response to chlorine decline.

Experts believe that this major achievement is the result of the series of international regulations and collaborations of several nations to ban the use of CFCs.

"We may have turned the corner on O₃ depletion," says Dr. Susan Strahan, an atmospheric scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, and the lead author of the study. "But it's important that all the nations of the world continue to abide by the Montreal Protocol (and its amendments) that ban CFC production."

The recovery is slow due to the long life of CFCs, which can remain in the atmosphere for decades, but the team believes that they expect the ozone hole to be gone between 2060 and 2080.

The benefits

Any rise in atmospheric ozone levels is expected to bring major benefits to life on earth.

• Blocks ultraviolet radiation responsible for problems from cataracts to skin cancers.
• Blocks the adverse effects of UV radiation on crop yields.
• Strengthens the belief that sends across a reminder that international collaborations can solve even the greatest environmental and public health problems.

Strahan concludes saying, "Science and policy CAN work together to solve global problems. I think people need to know this so they won't be discouraged about solving climate change."

References:

1. The good news about the ozone hole is even better than you think - (http://www.euronews.com/2018/01/09/good-news-about-ozone-hole-even-better-you-think-ncna835971)
2. Strahan, S. E., & Douglass, A. R. (2017). Decline in Antarctic ozone depletion and lower stratospheric chlorine determined from Aura Microwave Limb Sounder observations. Geophysical Research Letters, 44. https://doi.org/10.1002/2017GL074830

Source-Medindia