Scientists have discovered a huge all-season ozone hole in the lower stratosphere in the tropics, about as deep as the famous spring Antarctic hole, but about seven times larger. The observed data are in good agreement with cosmic ray-driven electron reaction (CRE) models and strongly suggest that the physical mechanisms of the Antarctic and tropical ozone holes are the same.

In AIP Publishing’s AIP Advances, Qingbin Lu, a scientist at the University of Waterloo in Ontario, Canada, reveals a large, all-season ozone hole — defined as a region with more than 25% loss of ozone compared to the undisturbed region of the atmosphere — — Located in the lower stratosphere above the tropics, it is as deep as the famous Spring Antarctic Hole, but roughly seven times larger.

“The tropics half of the Earth’s surface area and are home to about half of the world’s population,” Lu said. “The existence of the tropical ozone hole could be of great global concern.

“Depletion of the ozone layer leads to increased ground-level UV radiation, which increases the risk of skin cancer and cataracts in humans, weakens the immune system, reduces agricultural productivity, and negatively impacts sensitive aquatic life and ecosystems.”

Lu’s observations of the ozone hole surprised his scientific colleagues because conventional photochemical models did not predict it. His observations are in good agreement with cosmic ray-driven electron reaction (CRE) models and strongly suggest that the physical mechanisms of the Antarctic and tropical ozone holes are the same.

As with the polar ozone hole, about 80% of normal ozone values ​​are found depleted in the center of the tropical ozone hole. Preliminary reports indicate that ozone depletion levels in the equatorial regions have endangered large populations, and the associated UV radiation reaching these regions is much higher than expected.

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In the mid-1970s, atmospheric studies indicated that the ozone layer, which absorbs most of the sun’s ultraviolet radiation, may have been depleted due to industrial chemicals, primarily chlorofluorocarbons (CFCs). The discovery of the Antarctic ozone hole in 1985 confirmed the ozone depletion caused by CFCs. While bans on such chemicals have helped slow ozone depletion, there is that ozone depletion persists.

Lu said the tropical and polar ozone holes play an important role in cooling and regulating stratospheric temperatures, reflecting the formation of three “temperature holes” in the global stratosphere. The discovery could be critical to better understanding global climate change, he said.

Lu’s discovery builds on previous research on the mechanism of CRE-induced ozone depletion that he and his colleagues initially proposed about 20 years ago.

“The current findings require further careful study of ozone depletion, changes in ultraviolet radiation, increased cancer risk, and other negative impacts on health and ecosystems in tropical regions,” Lu said.


By Rebecca French

Rebecca French writes books about Technology and smartwatches. Her books have received starred reviews in Technology Shout, Publishers Weekly, Library Journal, and Booklist. She is a New York Times and a USA Today Bestseller...