How We Healed the Ozone Layer

Ozone over the Antarctic September 2019. Credit: NASA Ozone Watch

On September 16, 1987, 196 states and the European Union (a total of 197 parties) got together to sign the Montreal Protocol. Ozone Day has been held on that day since then, to commemorate this occasion.

In this age of terrifying news regarding humanity’s future on this planet, this ozone day we got some good news. New modelling by the UN’s Environmental Agency (UNEP) has indicated that the Ozone layer is on track to returning to 1980s values by 2060.This great news is due to the power of cooperation and coordination, which is what the Montreal Protocol resulted in.

Let’s talk about the ozone layer first. It is that region of the Earth’s stratosphere that absorbs most of the Sun’s ultraviolet radiation and contains high concentrations of Ozone (O3). This layer is found in the lower part of the stratosphere at around 15 to 35 km above the Earth. Keep in mind though that the thickness varies seasonally and geographically.

It was discovered in 1913, by Charles Fabry and Henri Buisson. Then G.M.B Dobson studied its properties in detail and even developed a spectrophotometer called the Dobsonmeter to measure it, modern versions of which we still use to this day.

What we discovered was that the ozone layer absorbs up to 99 % of the Sun’s medium frequency ultraviolet light, which otherwise would be damaging to life on Earth.

Enter the hydrocarbons, called the chlorofluorocarbons (CFCs). Some varieties had been used in fire extinguishers since the late 19th century and some were used for fire suppression in military aircraft as early as the 1920s. From 1928 onward, some CFCs started being used as refrigerants, and by the 1960s, were standard in fire extinguishers in labs, museums and art galleries because they would not cause water damage. Meanwhile, bromofluoroalkanes were being used to extinguish fires in warships. Consumption of CFCs increased drastically when they were included in aerosol sprays.

Research in 1976 revealed that the Ozone layer was being depleted by CFCs and there was concern that this would threaten life on Earth, including increasing the risk of skin cancers. Both chlorine and bromine react with the oxygen (O3) in the ozone layer and break it down, rendering it useless as a protective layer against UV radiation.

By 1985, it was clear that there was a hole in the ozone layer and approximately 10% had been eroded. In 1978, some countries, such as the US, Canada and Norway, had instituted bans on the use of CFCs in aerosol sprays but they continued to be used as refrigerants and in industrial cleaning.

Finally, in 1987 one of the most successful multilateral environmental efforts were undertaken and the Montreal Protocol was signed, with the objective to completely phase out CFCs. This was such a huge success that 99% of CFCs were removed from the products in which they were used. In 2018, it came to light that concentrations of some CFCs were increasing again, possibly from unregulated industry in China. This shows that there is still a need to remain vigilant. The Kigali Amendment to the protocol came into force this year (2019) and it aims to strengthen enforcement and continue to protect the ozone layer, while also phasing out hydrofluorocarbons (HFCs) that replaced CFCs because of their potential for greenhouse gas emissions.

The Montreal Protocol is clearly a great example of how human beings are capable of tackling global challenges through cooperation and solidarity. Nations have continuously worked for over 30 years to slash the use of ozone depleting chemicals and the result is now obvious: the ozone layer is healing.

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