Hi ,
Ozone holes have formed annually for the past 35 years in the Antarctic because of human-made chemicals. Thanks to unusually warm temperatures high above Antarctica, the ozone hole shrank to its smallest size on record!
Researchers say this has only happened two other times since ozone
observations began in the 1970s. The first time was during the winter of 1996-97 and the second during winter 2010-11. In both cases, the extreme ozone depletion was caused by unusual weather patterns that kept the Arctic colder for longer periods than most years.
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