Protecting the Protector

The Montreal Protocol of 1987 called upon the world to control the production and use of ozone-depleting substances (ODS) in order to protect the ozone layer—which is our very own protection from high levels of ultraviolet rays from the sun.

Nearly 30 years after the whole world joined forces to address the threat brought about by the thinning ozone layer, scientists at MIT confirm that the hole over Antarctica is starting to heal.

"We can now be confident that the things we’ve done have put the planet on a path to heal," said MIT lead researcher Susan Solomon, who also happens to be the first to distinguish the conditions of temperature and sunlight under which chlorine could eat away at the ozone layer, back in 1986.


They found evidence that the September ozone hole has shrunken by over 4 million square kilometers since. The world’s efforts to reverse the damage are showing promising results, and that is despite some setbacks caused by sulfur dioxide from volcanic eruptions.

In 2015, the hole reached a record size, which had scientists puzzled. This paper analyzed and made sense of the factors that contributed to that incident.

“Why I like this paper so much is, nature threw us a curveball in 2015,” says Ross Salawitch, professor of chemistry and biochemistry at the University of Maryland. “People thought we set a record for the depth of the ozone hole in October 2015. The Solomon paper explains it was due to a specific volcanic eruption. So without this paper, if all we had was the data, we would be scratching our heads — what was going on in 2015?”

The team measured “fingerprints” and found a substantial decline in atmospheric chlorine from chlorofluorocarbons (CFCs), which are ozone-depleting substances emitted through old dry cleaning methods, refrigerators, and aerosols.

Aerosol sprays contain CFCs.

"It showed we can actually see a chemical fingerprint, which is sensitive to the levels of chlorine, finally emerging as a sign of recovery," said one of the researchers, Diane Ivy.

Not a Time for Complacency

"This is a reminder that when the world gets together, we really can solve environmental problems," Solomon said. "I think we should all congratulate ourselves on a job well done."

The hole is estimated to be completely and permanently closed by 2050, provided the world keeps progress steady.


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