Ozone layer's hole was reduced this year, but human's efforts are not the reasons.
The ozone hole in Antarctica hit the smallest annual peak on record since tracking started in 1982, the National Oceanic and Atmospheric Administration and NASA announced.
However, the milestone does not mean humanity has resolved the problem. Scientists attributed the comparatively small ozone hole to unusually mild temperatures in that layer of the atmosphere.
The annual ozone hole, according to NASA and NOAA, reached its peak extent of 6.3 million squares miles on September 8 and shrank to less than 3.9 million square miles in September and October. The ozone hole had a range of heavily depleted ozone that measures between seven and 25 miles above Antarctica's stratosphere surface.
"During years with normal weather conditions, the ozone hole typically grows to a maximum of about 8 million square miles," the agencies noted in a news release.
The federal science agencies said the weather systems, for the third time in 40 years, had created warm stratospheric temperatures that placed the brakes on ozone loss. They reported the same weather models led to unusually tinier ozone holes in 1988 and 2002.
Sussan Strahan, an atmospheric scientist at the NASA's Goddard Space Flight Center in Maryland, said in a news that it is a rare event that they are still trying to comprehend. They'd likely be seeing at much more ozone holes if the warming had not happened.
How the polar vortex fixed this
"Sudden stratospheric warming" events—known as weather systems that helped minimized ozone depletion—were unusually powerful this year. NASA and NOAA reported that temperatures during September were 29 degrees higher than average.
This weather event serves to weaken the Antarctic polar vortex as stratospheric warming episodes in the Northern Hemisphere happened. Strips of high-speed air surrounding the South Pole that typically concentrate the coldest air near or over the pole itself were used.
From an average wind speed of 161 miles per hour to 67 miles per hour, the Antarctic polar vortex was outbalanced and significantly slowed down. The vortex allowed air to be absorbed in the lower stratosphere and restrained cloud formation.
The reconfigured weather map likewise assisted in sending ozone-rich air from other regions of the Southern Hemisphere instead of entirely closing off the polar region. The situation eased boost the ozone levels.
The polar vortex is expected to be strengthened with the help of a future warmer climate, according to NOAA scientist Amy Butler's official Twitter account.
Nice article! I agree with it. Perhaps it should be emphasized that there is no expected increase in SH SSWs in a future warmer climate (we expect the SH polar vortex, if anything, to strengthen). — Amy H Butler (@DrAHButler) October 21, 2019
Historic context
The ozone hole's discovery by the British Antarctic Survey in 1985 caused international action in contrast with global warming. Their data resulted in an international treaty that experts considered the most prosperous environmental compliance to date.
Policymakers were using the treaty to address hydrofluorocarbons (HFCs) and other ozone-depleting chemicals that are also among the causes of environmental pollution. Atmospheric concentrations of chlorofluorocarbons (CFCs) have even declined since 2000. However, these chemicals are still significantly plentiful in causing the ozone hole in the South Pole.
Scientists likewise expect the ozone hole to shrink to its 1980 size by 2070, assuming that the consumers remain to use CFCs at recent rates and that no ozone-depleting chemical substitutes are found and widely used.
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