It is normal for the hole to get larger or smaller at times, but now it has become noticeably larger.
Some researchers believe this is due to the eruption of an undersea volcano in Tonga early last year. This released a lot of water vapor into the air. This may have caused more ozone to decompose than usual.
But ESA researchers don’t know that for sure yet. This is an ongoing investigation.
Ozone is a gas in the atmosphere that protects us from harmful radiation from the sun. Ozone concentrations at the poles fluctuate throughout the year. We talk about a hole in the ozone layer when the amount of ozone drops below a certain level.
The level is at its lowest in September and October every year. As temperatures rise over the Southern Hemisphere, ozone depletion slows and the ozone layer thickens again. The level often returns to normal in December.
The strength of the winds blowing around Antarctica also affects the size of the hole in the ozone layer. The wind can form a kind of barrier, meaning that less warm (or cold) winds from other areas can enter.
The hole in the ozone layer was very large in the 1970s and 1980s. This was due to harmful substances found in refrigerators, among other things. That’s why these substances were banned in 1987.
The ozone layer has not yet fully recovered. Scientists expect that the ozone layer will need until 2050 to fully return to pre-1975 levels.
