Research finds Antarctica ozone hole getting smaller

Cesar Mills
January 6, 2018

The research spawned the idea that the hole was forming in the ozone layer, and inspired global action. Now, NASA scientists report that they have the first direct evidence that the ozone hole above the icy continent is clearly getting plugged.

If CFC concentrations in the stratosphere were not declining, and thus the smaller ozone holes were only due to temperature fluctuations, Strahan and Douglass would have found that the concentrations of HCl and N2O were relatively stable compared to one another.

The ozone layer acts as a protective shield around the Earth, absorbing the Sun's harmful ultraviolet radiation which can cause cancers, suppress the immune system in humans and damage plant life. "This is when we want to measure ozone loss". "And even then, there might still be a small hole". Ozone holes occur naturally from cooling, but man-made chemicals greatly accelerate their formation. Hydrochloric acid is a chemical that forms once chlorine has destroyed the ozone itself.

Antarctic ozone hole maxima, from 2017 (left) and 2006 (right).

NASA's latest announcement came in November where it said that the layer measured was now smallest since that in 1988.

A new study done by the National Aeronautics and Space Administration (NASA) and based on the data collected from the Aura satellite, claims that a decline in the ozone-depleting chemicals has resulted in a 20 per cent less depletion of the ozone layer since 2005.

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Direct ozone measurements, taken by Aqua from 2005-2016, show that there is less ozone disappearing over the southern winter.

For example, researchers measured the levels of chlorine, a primary source of ozone depletion, and found it's falling nearly 1 percent a year.

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. On average, chlorine levels are declining by about 0.8 percent annually, the authors reported in the Geophysical Research Letters.

Despite the encouraging results, Anne Douglass, a fellow atmospheric scientist at Goddard, believes a complete ozone recovery is still a long way off. "CFCs have lifetimes from 50 to 100 years, so they linger in the atmosphere for a very long time", Douglass said.

"This is very close to what our model predicts we should see for this amount of chlorine decline". Although there have been definite signs of recovery for the ozone hole over the years, it had still been hard to show that this recovery was a direct result of CFC regulations. "But we're not yet seeing a clear decrease in the size of the ozone hole because that's controlled mainly by temperature after mid-September, which varies a lot from year to year".

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