According to a Canadian scientist, an ozone hole, seven times bigger compared to the Antarctic ozone hole, is presently sitting over tropical regions and has been since the 1980s.
Time-series decadal mean annual ozone changes, differences in annual ozone climatology, and decadal mean zonal mean latitude-altitude distributions of the temperature reveal scope of “new” ozone hole. Image Credit: Qing-Bin Lu.
In AIP Advances, by AIP Publishing, Qing-Bin Lu, a scientist from the University of Waterloo in Ontario, Canada, discloses a huge, all-season ozone hole — defined as an area of ozone loss larger than 25% compared with the undisturbed air — in the lower stratosphere over the tropics comparable in-depth to that of the familiar springtime Antarctic hole. However, the area is approximately seven times greater.
The tropics constitute half the planet’s surface area and are home to about half the world’s population. The existence of the tropical ozone hole may cause a great global concern.
Qing-Bin Lu, Scientist, University of Waterloo
Lu added, “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.”
The observation of the ozone hole made by Lu comes as a surprise to his co-workers in the scientific community, as it was not forecasted by traditional photochemical models. His data agrees well with the cosmic-ray-driven electron reaction (CRE) model and powerfully denotes the identical physical mechanism functioning for both tropical and Antarctic ozone holes.
As far as the polar ozone hole has been considered, around 80% of the normal ozone value is discovered to be depleted at the center of the tropical ozone hole. Preliminary reports exhibit ozone depletion levels over equatorial regions are threatening huge populations and the linked UV radiation reaching such regions is much greater compared to what is anticipated.
In the mid-1970s, atmospheric research indicated that the ozone layer, which absorbs the majority of the ultraviolet radiation of the sun, may be depleted due to industrial chemicals, mainly chlorofluorocarbons (CFCs).
The 1985 discovery of the Antarctic ozone hole affirmed CFC-caused ozone depletion. Even though bans on such chemicals have helped to slow down ozone depletion, evidence implies ozone depletion persisted.
Lu stated that the polar and tropical ozone holes play a significant role in cooling and controlling stratospheric temperatures, reflecting the development of three so-called “temperature holes” in the global stratosphere. He stated this finding might prove critical to comprehending global climate change in a better way.
The discovery by Lu builds on earlier studies of the CRE-initiated ozone-depleting mechanism that he and his collaborators originally suggested nearly 20 years ago.
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.
Qing-Bin Lu, Scientist, University of Waterloo
Journal Reference:
Lu, Q.-B., et al. (2022) Observation of large and all-season ozone losses over the tropics. AIP Advances. doi.org/10.1063/5.0094629.