Ozone protects Earth from Sun's harmful ultraviolet rays. (Representative Photo)
Scientists have discovered a large hole in ozone gas layer, which envelops the Earth and protects it from the Sun's harmful ultraviolet rays. The hole is located in the lower stratosphere and is seven times bigger than the one over Antarctica, according to a paper published in AIP Advances.
The newly-discovered all-season hole sits over the tropics and has been there for more than 30 years, said Qing-Bin Lu, a scientist from the University of Waterloo in Ontario, Canada, who made the discovery.
What is an ozone hole?
The ozone hole is not technically a "hole" where no ozone is present, but is actually a region of exceptionally depleted levels of the gas, according to American space agency NASA.
Environmentalists describe the ozone hole as an area where the loss of the gas is 25 per cent more than the undisturbed atmosphere.
What causes an ozone hole?
The ozone hole has been discovered above the tropics. (Representative Photo)
NASA says that the depletion of the ozone gas is caused by chlorofluorocarbons (CFCs). These chemicals escape into the atmosphere from refrigeration and propellant devices and other such things. In the lower atmosphere, they are so stable that they persist for years, even decades, according to NASA website.
These CFCs release chlorine after coming into contact with the ultraviolet rays of the Sun, which ultimately destroy ozone.
Ozone hole and the concern
According to Lu, the existence of the tropical ozone hole may cause great global concern.
"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 researcher said in his observation in the paper.
Lu surprised other scientists by the discovery, as the ozone hole was not showing on the modeling most researchers use.
Lu said the tropical and polar ozone holes play a major role in cooling and regulating stratospheric temperatures, mirroring the formation of three "temperature holes" in the global stratosphere. He said this finding may prove crucial to better understanding global climate change.