Ozone hole is officially shrinking, proof that worldwide treaties can be effective

Gwen Vasquez
January 6, 2018

The smaller size of the ozone hole in 2017 is partly due to warmer temperatures measured over the Antarctic, according to NASA, since the chemical reactions that cause the wide range of chlorofluorocarbons to deplete ozone happen more readily with colder temperatures.

Susan Strahan, lead author and atmospheric scientist at NASA's Goddard Space Flight Centre, said, "We see very clearly that chlorine from [chlorofluorocarbons] is going down in the ozone hole, and that less ozone depletion is occurring because of it".

The CFC's are broken down into chlorine by the sun's ultraviolet rays, thus causing the depletion.

But the new study is the first to use measurements of the chemical composition inside the ozone hole to confirm that not only is ozone depletion decreasing, but that the decrease is caused by a decline in CFCs.

After CFCs were banned, scientists eventually observed that the ozone layer started recovering. As the ozone layer acts as a protective blanket against the most harmful wavelengths of ultraviolet light, the so-called (and then-expanding) hole over Antarctica brought with it visions of skin cancer, sunburn, cataracts, and havoc to plants and animals, for starters.

An worldwide ban on substances called chlorofluorocarbons (CFCs) has resulted in a reduction in the amount of chlorine present in the atmosphere, which was damaging the ozone layer.

Strahan's study is the first to look directly at measurements of chemicals to argue that the shrinking hole stems from the ban of CFCs.

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During the 1970s and '80s, it was reported that a class of industrial chemicals, the chloro-flurocarbons (CFCs), were damaging the ozone layer, a region of the stratosphere rich in this reactive form of oxygen.

Former Secretary of State John Kerry gestures as he delivers a speech during the 28th Meeting of the Parties to the Montreal Protocol in Kigali, Rwanda on October 14, 2016.

In September of 2017, the Antarctic ozone hole reached its smallest maximum area since 1988, dropping below 20 million square kilometres for the first time in 29 years. However, their study found that hydrochloric acid concentrations in the ozone hole were declining by comparison, by an average of 0.8 per cent per year.

"This is very close to what our model predicts we should see for this amount of chlorine decline", Strahan said.

Scientists at NASA said they had located the largest ozone hole ever recorded, in a report released October 3, 2000. Measurements in the past have shown that the hole was shrinking, leading to premature celebration that humanity had done something good for once, only to discover the following year that the hole was once again larger.

Even if the results of the new study do hold true, scientists say it will take until at least 2060 for the hole in the ozone to vanish.

The hole in the ozone layer is getting smaller and smaller.

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