“Big” the ozone hole the unexpected has been detected on Earth atmosphere almost throughout the tropical region.
The hole is a year-round void on the planet ozone layer and seven times larger than the better-known Antarctic ozone hole that opens every spring.
Professor Qing-Bin Lu, a scientist at the University of Waterloo in Ontario, Canada, said that according to his research, the sinkhole has existed for more than 30 years and covers an area so large that half of the world’s population has been affected.
He said Independent: “Unlike the Antarctic ozone hole, which appears only in spring, the tropical ozone hole has been visible in all seasons since the 1980s, and its area is about seven times larger.
“[It] It may be of global concern because it may lead to increased UV radiation at ground level and the associated risks of skin cancer and cataracts, and other adverse effects on health and ecosystems in tropical regions.
According to him, “there are preliminary reports indicating that levels of ozone depletion in equatorial regions are already posing a threat to large populations there, and that the associated UV radiation reaching the regions is greater than expected.”
Professor Lu talked about the discovery of the giant ozone layer Independent: “It sounds incredible that the great tropical ozone hole was not discovered earlier. But there are some inherent difficulties in making this discovery.
“First, no tropical ozone hole was expected from basic photochemical theory. Second, unlike the Antarctic/Arctic ozone holes, which are seasonal and appear mainly in spring, the tropical ozone hole remains constant throughout the seasons and is therefore invisible in the primary observed data.
As with the Antarctic ozone hole, the center of the tropical ozone hole has been found to have lost about 80 percent of its normal ozone value.
The new study also highlighted differences in current theories about how ozone is depleted.
In the past, the presence of chlorofluorocarbons (CFCs) was considered the biggest cause of ozone depletion. The Montreal Protocol of 1987, which banned them, saw a significant decrease in their use.
But despite the global ban, the largest, deepest and most persistent ozone holes over Antarctica were still observed in the late 2000s and 2020-2021.
“This was unexpected from any of the photochemistry-climate models,” Professor Lu said.
A separate theory of ozone depletion, known as the cosmic ray-driven electron reaction (CRE), in which cosmic rays from space reduce ozone in the atmosphere, was first proposed by Professor Lu and colleagues two decades ago.
He said Independent: “The observed results strongly suggest that both the Antarctic and tropical ozone holes must originate from the same physical mechanism, and the CRE mechanism showed excellent agreement with the observed data.”
He added: “CFCs are undoubtedly the main ozone-depleting gases, but cosmic rays are a major trigger for both polar and tropical ozone holes.”
The study was published in the journal AIP Advances.
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