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In a new UN report, specialists revealed that the ozone layer is officially back on track to be restored to full strength in decades.
And while that does not mean all of our climate crisis woes have been resolved (far from it), it’s a rare nugget of optimism about our future.
Why is the ozone layer so important?
The ozone layer is the thin part of the Earth’s atmosphere which absorbs most of the Sun’s ultraviolet radiation.
If the ozone layer is weakened and radiation breaks through, it could cause significant harm to all life on Earth and the planet as a whole.
Ultraviolet rays affect DNA, trigger sunburn, and increase long-term issues like skin cancer.
Why is the ozone layer so damaged?
The ozone layer started to thin back in the 1970s, due to emissions from chemicals in spray cans, fridges, foam insulation and air conditioners, called Chlorofluorocarbons.
It wasn’t until 1985 that scientists uncovered a huge hole in the ozone layer, which continued to expand until 2000.
The largest hole at the time stretched to an astounding size – 29.9 million square kilometres.
Why do scientists now think it will be fixed sooner rather than later?
The Montreal Protocol, signed in 1987 and effective in 1989, saw 46 countries promise to phase out the chemicals believed to have eroded the ozone layer.
It then became the first UN treaty to reach universal ratification.
Close to 99% of these banned substances have now been phased out, with China in particular working to eliminate the chemical CFC-11.
The new report said the Chinese emissions had threatened to delay the layer’s recovery, but scientists now believe it was only delayed by a year.
More than 100 of these compounds were banned and phased out over time.
After 2000, the effect of the protocol finally started to be felt as the hole stopped growing – although progress is not fast.
For instance, in 2020, the largest hole found in the ozone layer was 24.8 million square kilometres wide. This is just a small, but substantial, change from the largest hole seen in 2000, which was 5 million square kilometres larger.
Although the protocol was announced decades ago, the delay in recovery partially stems from the build-up of chemicals.
They don’t immediately enter the atmosphere, but over time, break up to harm the ozone layer. So the full effect of chemicals released now won’t be felt for some time yet.
If current policies stay in place, the ozone layer should go back to 1980 levels this century.
As one of the report’s authors, Stephen A. Montzka, said: “The emissions dropped amazingly abruptly.”
In 2066, it should be back to 1980 levels over the Antarctic – which has been the worst affected area – and in 2045, it should be back to 1980 levels over the Arctic.
In roughly two decades’ time (2040) ozone layers between the polar regions should reach pre-1980 levels.
“The recovery of the ozone layer is on track,” according to David W.Fahey, the director of the National Oceanic and Atmospheric Administration’s Chemical Sciences Laboratory and a co-chairman of the protocol’s scientific assessment panel.
He said that “peak destruction” of the ozone layer around the world is now “behind us” and he suggested that this was due to the effective “control measures” of the Montreal Protocol which all nations have adopted.
However, the scientists have warned that the restoration of the ozone layer is not guaranteed.
Measures which have been proposed to decrease global warming could actually undo this progress, particularly the proposal to send millions of sulphur dioxide into the upper atmosphere, known as stratospheric aerosol injections.
This was meant to cool the atmosphere by using these aerosols to reflect the sun’s rays before it reaches the surface, but it could send the recovery plans backwards – and disrupt weather.
This combination of images made available by NASA shows areas of low ozone above Antarctica on September 2000, left, and September 2018. The purple and blue colours are where there is the least ozone, and the yellows and reds are where there is more ozone.
What does this mean for the climate crisis?
Damage to the ozone layer does not have a direct impact on the climate crisis, but by reducing the amount of harmful emissions, this should – indirectly – help alleviate global warming.
Many of the chemicals depleting the ozone layer were greenhouse gases, meaning phasing them out will still prevent an estimated 0.5C of warming by the middle of the century.
This is, by no means, a silver bullet to solve the climate crisis though, as is clear by the extreme weather patterns we’re still experiencing around the globe.
But, this is one of the several steps we’ve taken recently which show our attitude towards the climate is changing.
For instance, the UK is also leading the Global Ocean Alliance, which aims to improve biological diversity around the world. It wants to protect at least 30% of the global ocean by 2030 – known as the 30by30 target.
The acid rain, a crisis which emerged in the 1970s, 80s, and 90s, is now largely seen as a thing of the past, now the production of harmful products like sulphur dioxide emissions have reduced. Similarly, leaded petrol is banned from most developed countries.