This year, the hole in the ozone layer over Antarctica has grown larger, and formed later, than at any point in recent years. Expanding to a hole the size of North America, it makes the 2015 hole area the fourth largest on record.
While the gap in the ozone is known to expand and contract over the year, it is still largely the result of man-made chemicals that were pumped into the atmosphere during the 1980s. Scientists at NASA have, however, said that there is no need to panic, as the long-term trends show that the ozone is still on track to recover.
“While the current ozone hole is larger than in recent years, the area occupied by this year's hole is consistent with our understanding of ozone depletion chemistry and consistent with colder-than-average weather conditions in Earth's stratosphere, which help drive ozone depletion,” Paul Newman, chief scientist for Earth Sciences at NASA's Goddard Space Flight Center, explained in a statement.
The ozone surrounding our planet absorbs most of the ultraviolet radiation from the Sun, protecting us from its harmful effects. During the 1980s, it was found that the production of man-made compounds, such as chlorofluorocarbon (CFC), was massively damaging to the ozone layer, causing it to thin so much that it was likely to result in adverse effects on human health and the environment, leading to the phasing out of CFCs. But over Antarctica, even since the ban in CFCs, the hole in the ozone layer has remained.
Ozone is made up of three oxygen atoms bonded together and is created naturally in the stratosphere around 32 kilometers (20 miles) up in the atmosphere by sunlight. The total amount of ozone in the atmosphere is thought to be around three billion tons, but even then this only accounts for around 0.00006% of the atmosphere. Chemically active forms of chlorine and bromine that make it up into the stratosphere, much of which comes from human pollution, reacts with the ozone and destroys it. It is this that is thought to be playing havoc with the ozone over Antarctica.
“This year, our balloon-borne instruments measured nearly 100% ozone depletion in the layer above South Pole Station, Antarctica, that was 14 to 19 kilometers (9 to 12 miles) above Earth's surface,” Bryan Johnson, from the NOAA, said in a statement. “During September we typically see a rapid ozone decline, ending with about 95% depletion in that layer by October 1. This year the depletion held on an extra two weeks resulting in nearly 100% depletion by October 15.”
This year’s record does not, however, change the long-term predictions of the recovery of the ozone layer, and so shouldn’t really be a cause for alarm. According to the NASA and the NOAA, the ozone hole should be back to 1980s levels by 2070.