The early arrival has prompted concerns from some scientists that a larger-than-average hole may further warm the Southern Ocean while the level of Antarctic sea ice is at a record low.
Generally, the hole appears each spring (September), but it has been showing signs of depletion as early as last month this year and it has already reached 17.1 million sq km.
The stratospheric ozone layer protects life on Earth by absorbing ultraviolet light.
Without it, damage is done to DNA in plants and animals (including humans) and leads to sun burns and skin cancer.
Scientists estimate about 80% of the ozone’s depletion is caused by people using chlorine and bromine.
Bush fires and volcanic eruptions also have an impact.
Data from July this year showed there were some minor ozone depletion events, but in the first week of this month, the ozone hole area reached 6.2 million sq km.
Scientists said it was an early start for the ozone hole this year, and the value at the end of this month’s first week was in the upper 10th percentile for this time of year.
The second and third weeks of this month saw a rapid increase in the ozone hole area, reaching 9.1 million sq km on August 8 — a record high for this time of year — before dropping back to 3.6 million sq km on August 11.
The area then increased very rapidly to 17.1 million sq km on August 18, before dropping back to 14.4 million sq km on August 20, which was very large for this early in the ozone hole season.
More recently, the hole grew again to 15.3 million sq km on August 27.
Niwa Lauder Atmospheric Research Station scientist Dr Richard Querel said the primary interest of this ozone hole season would be how much influence last year’s Hunga Tunga-Hunga Ha’apai (HT-HH) underwater volcanic eruption would have on the metrics of this year’s ozone hole — how early it started, how large it got, how deep it was and how long it lasted.
"We know that the unprecedented amounts of additional water vapour along with aerosols from the HT-HH eruption were essentially blocked outside of the polar vortex last year, and so were kept away from the pole and were not part of last year’s ozone hole chemistry.
"However, we also know that that new material will definitely play a part in this year’s ozone hole, having already created colder conditions over the pole which are ideal for generating a larger deeper ozone hole.
"While it is very early days still for this spring’s ozone hole and we can’t say too much yet, it has already formed earlier than normal, and we are continuing to make our measurements at Scott Base and Arrival Heights, Antarctica to help monitor how it evolves."
