The delayed effect of the eruption of Tonga’s underwater Hunga volcano last year has caused an ozone hole over Antarctica to open weeks earlier than usual.
The hole in the ozone layer – the portion of the stratosphere that protects our planet from the Sun’s ultraviolet rays – has been gradually healing over the past few decades thanks to the 1987 Montreal Protocol’s phase-out of ozone-destroying chemicals like chlorofluorocarbons (CFCs).
Still, this layer thins every September to form an ‘ozone hole’ above the South Pole.
In recent years, the hole has started to open in mid-to-late August, when spring begins in the southern hemisphere.
The increasing sunlight also drives the ozone-destroying activity of the remaining CFCs in the atmosphere. It then closes in November or early December.
This year, the ozone hole has started to open several weeks earlier at the beginning of August. By August 10, it had already grown to over 3 million square kilometres in size.
Another reason for the earlier opening in the ozone layer is the level of Antarctic sea ice being at a record low.
Sea ice reflects sunlight, which helps to keep the Earth cool. However, with less of it, more sunlight is absorbed by the ocean, which warms the atmosphere and further depletes the ozone layer.
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