Senior Editor
hole in ozone layer over the tropics

There’s a hole in the ozone layer in the tropics that we didn’t even know existed… and it’s big. Photo: Sean Oulashin/Unsplash

The Inertia

If you are of a particular age, you likely remember all that talk in the nineties about the hole in the ozone layer. It was, for a time, the planet’s most-pressing environmental concern. Luckily, we did something about it and things would have been far worse if we hadn’t. But researchers recently found another one they didn’t know existed.

This new (to us, anyway) hole was detected over the Earth’s tropical regions. It stays open all year long. It somehow evaded researchers, who now think it’s likely that it’s been open since the 1980s.

An ozone hole is, put very simply, bad for us. The ozone layer protects us from ultraviolet radiation, too much of which is responsible for a whole host of issues like skin cancer, cataracts, damage to plants, crops, and animals as well as reproductive issues in fish and phytoplankton.

When a portion of the ozone layer loses at least 25 percent more 03 (trioxygen) than the surrounding areas, we call it a hole. The one that caused all that hub-bub in the 1990s was over the Antarctic, and after a few decades of alarm bells, the world got together and decided to do something about it. After it was figured out that chlorofluorocarbons (CFCs), used in aerosols and cooling devices were likely the cause of the issue, governments around the world signed onto 1987’s Montreal Protocol, which, in part, phased out the chemicals that were thinning the ozone layer. And it worked. Without those measures, things would be far worse today.


But all is not perfect up there, as evidenced by the new discovery. The tropical ozone hole was first reported in the journal AIP Advances, and it’s staggeringly big: seven times larger than the one over the Antarctic ever was.

“The tropics constitute half the planet’s surface area and are home to about half the world’s population,” said Qing-Bin Lu, a University of Waterloo scientist and author of the report. “The existence of the tropical ozone hole may cause a great global concern.”

Not only is the tropical hole larger than the Antarctic, but it stays open all year around. While the Antarctic one still exists, it has a seasonal cycle, thinning out in September and October, then thickening again over the course of the rest of the year.

“The depletion of the ozone layer can lead to increased ground-level UV radiation, which can increase risk of skin cancer and cataracts in humans, as well as weaken human immune systems, decrease agricultural productivity, and negatively affect sensitive aquatic organisms and ecosystems,” said Lu. “The present discovery calls for further careful studies of ozone depletion, UV radiation change, increased cancer risks, and other negative effects on health and ecosystems in the tropical regions.”

While only time will tell whether the world can come together again to solve a problem that we’ve created and affects all of us, the discovery of the tropical ozone hole comes at a time in human history that feels a little too divided to see anything as meaningful happen as the Montreal Protocol. But fingers crossed, right?



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