The ozone layer is HEALING: Hole over Antarctic is closing and disappearance of Earth’s protective layer is slowing down
Written by Sarah Griffiths
The hole in the ozone layer over the Antarctic has finally begun to ‘heal’ after persisting for years.
A new study has recorded an ozone increase in the icy region, suggesting the agreement signed nearly three decades ago to limit the use of substances responsible for ozone depletion, is having a positive effect.
As well as creating an identifying ozone increase, it’s slowing the rate of ozone depletion in the stratosphere – Earth’s second major atmospheric layer.
Ozone is a gas composed of three oxygen molecules which can be hazardous to our health on the ground, but in the upper atmosphere it protects us by soaking up ultraviolet radiation from the sun.
Without it, the planet’s surface would be exposed to dangerous levels of UV-B rays which can shred DNA, leading to mutations that cause cancers.
Towards the end of the 20th Century, the ozone was found to have been depleted by the now banned chlorofluorocarbons (CFCs), which react with the ozone as they break down.
The Montreal Protocol on Substances that Deplete the Ozone Layer, came into effect in 1989 and was an international treaty designed to protect the ozone layer by phasing out CFCs.
Understanding the degree to which the ozone is healing in response to this agreement and related efforts is of enormous interest to scientists and policy makers alike.
While previous research has shown some early signs of stratospheric ozone recovery in Antarctica since the agreement’s signing, the signs have largely been of a reduced rate of ozone decline and levelling off of ozone depletion.
Less has been documented about ozone increase in the polar regions and in October 2015 the Antarctic ozone hole reached a record size, providing a conflicting result.
Susan Solomon, a Professor of Atmospheric Chemistry and Climate Science at MIT and her colleagues examined polar ozone trends since 2000, using a combination of direct ozone measurements and model calculations.
They identified several consistent signals of ‘healing’ in the Antarctic ozone layer, particularly in the month of September, when they found regular, seasonal increases in ozone column amounts.
The researchers also evaluated changes in ozone health caused by natural factors including volcanic eruptions.
They say that since about 2005, eruptions have delayed healing and made a large contribution to the inter-annual variability in ozone loss in recent years.
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