NASA scientists find proof reduced chlorine levels causing ozone hole to shrink

A study published Thursday in the scientific journal Geophysical Research Letters shows that ozone depletion over Antarctica has decreased by 20 percent since 2005 due to a declining rate of chlorine in the atmosphere.

The paper’s findings are significant as it marks the first time evidence has been found chlorine levels are being reduced in the ozone layer above Antarctica, which suggests the 1989 global ban on chlorofluorocarbons (CFCs) and other atmospheric pollutants, known as the Montreal Protocol, is working as intended.

Previous to the agreed upon framework, scientists found a significant loss of the gas compound trioxygen, or ozone, in the Earth’s lower stratosphere in 1985, following five-and-half decades of industrial CFC usage.  Ozone acts as a natural atmospheric filter, protecting humans and other forms of life from the Sun’s harmful ultraviolet rays.

Ozone hole above Antarctica at peak extent (courtesy

Previous to the latest findings, NASA and NOAA issued a joint statement in November announcing the ozone hole as observed in September 2017 was the smallest its been since 1988, although mainly due to above-average atmospheric temperatures.

Over 12 years of observation through satellite data, however, NASA scientists Anne Douglass and Susan Strahan found that the concentration of chlorine in Antarctica’s stratosphere has declined by an average of .8 percent per year.  While Southern Hemisphere’s ozone layer is on-the-mend, it will be a long time before its completely repaired.

“CFCs have lifetimes from 50 to 100 years,” said Douglass, the study’s co-author. “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.”

Watch a short explanatory video by NASA Goddard Space Flight Center atmospheric scientist Susan Strahan below.


[Ars Technica] [Photo courtesy Getty Images via The Express]