Ozone layer recap – the hole story in brief.
The ozone layer is an important part of our atmosphere, absorbing almost all of the sun’s harmful ultraviolet (UV) radiation.
Long-term exposure to high levels of UV-B, or any exposure to UV-C, is harmful to human health and damaging to most animals, plants and microbes. In short, the ozone layer plays a crucial role in protecting all life on Earth.
In the 1970s, scientists first hypothesised that the ozone molecules (O3) which form the ozone layer could be destroyed by the chlorine from chlorofluorocarbons (CFCs), man-made chemicals which were used in thousands of products around the world, from air-conditioners and refrigerators to aerosol sprays, asthma inhalers and building insulation.
Over the following years, evidence supporting their concerns grew and when scientists discovered a hole in the ozone layer above the Antarctic in the mid-1980s, the international community was spurred into action. The Montreal Protocol was signed in 1987, with the explicit aim of protecting the ozone layer by phasing out ODS.
To this day, the Montreal Protocol is the only United Nations environmental treaty to be ratified by every country in the world and it is defined by a catalogue of successes:
99 per cent of the ODS controlled under the Protocol have been phased out
the ozone layer is recovering and, if the Protocol continues to be fully implemented, should return to 1980 levels by 2066
hundreds of millions of people worldwide will be protected from skin cancers and eye cataracts, resulting in about $1.8 trillion in global health benefits
as ODS are potent greenhouse gases, their phase-out has already avoided hundreds of billions of tonnes of carbon-dioxide equivalent emissions
in 2016, the Montreal Protocol formally became a climate treaty with the adoption of the Kigali Amendment, a global agreement to phase down production and consumption of hydrofluorocarbons (HFCs). HFCs do not deplete ozone but are climate-harming gases used as substitutes for ODS. Successful implementation of the Kigali Amendment will avoid up to a half a degree of warming by the end of the century.
The Montreal Protocol has done much over the past 36 years to secure its crown as the world’s most successful environmental treaty, but while its success deserves to be celebrated, its work is far from done.
The spirit of increasing ambition that has put the recovery of our ozone layer back on track, and has taken action to limit the climate impact of HFCs, now needs to be reinvigorated once more to address the next set of challenges lining up against it.
