Manuela Callari
Dr Manuela Callari is a Sydney-based freelance science writer who specialises in health and medical stories.
It’s not every week that we get to share an uplifting story about the environment. In January the UN-backed Scientific Assessment Panel to the Montreal Protocol on Ozone Depleting Substances issued its quadrennial assessment report: the ozone layer is on track to heal completely within 40 years. It was once a major environmental threat, but it is now an example of how scientists, policymakers and industry can work together to solve major environmental problems.
Global efforts to mitigate the climate crisis, however, have not had the same desired effect. What can we learn from this success story to help us deal with today’s, possibly even more daunting, environmental challenges?
A hole in our roof
In June, 1974, scientists Professor Sherry Rowland and Professor Mario Molina suggested that human-made chlorofluorocarbons (CFCs) could break down in the stratosphere, releasing chlorine that could attack the ozone layer – a three-oxygen molecule gas coat that protects the Earth from extreme UV radiation.
These gases were used to make foams for air conditioners and refrigerators, as well as deodorants and hairspray cans. When released CFCs are inert, meaning they do not react with anything. They build up in the atmosphere and eventually wind up in the stratosphere over Antarctica.
In 1985, scientists from the British Antarctic Survey reported a substantial ozone decline over Antarctica, confirming Rowland and Molina’s hypothesis. Satellite images showed a significant depression in the ozone layer — as if somebody had dug a hole in it.
The ozone hole quickly became the scientific community’s most pressing environmental challenge. The years that followed saw intense research that proved conclusively that the ozone layer was being harmed and pointed to chlorine compounds as the cause.
Pushback is to be expected when scientists develop a new hypothesis. The scientific community requires time and data to reach an agreement. That is how the scientific method works.
But policymakers seek certainty. Industries are concerned about the loss of dollars.
Nonetheless, it only took governments two years to take action. On September 16, 1987, the Montreal Protocol, now signed by every country, banned the production of CFCs and replaced them with their non-ozone-depleting cousins, hydrofluorocarbons (HFCs).
In 2006, the average area of the ozone hole peaked at 27.4 million square kilometres. In 2022, the hole over Antarctica had an average area of 23.2 million km2.
The ozone layer: a tremendous success in the fight against climate change
Scientists only began understanding the link between ozone depletion, climate change, and solar UV radiation about 20 years after the Montreal Protocol was signed.
Because of ozone depletion over Antarctica, the large westerly wind band that circles the continent has strengthened and moved further south. Meanwhile, global warming is expanding the Equatorial zone. These two forces shift climate zones across the Southern Hemisphere to the south end of the Earth, exacerbating climate change effects.
Sharon Robinson, a Professor at the University of Wollongong and deputy director of Securing Antarctica’s Environmental Future research program, explains the healing of the ozone layer has slowed down climate change by shielding the Earth from sunlight and saving our planet from getting hotter.
It is estimated that banning CFCs has avoided half a degree to one degree of global warming.
CFCs and HFCs are nevertheless potent greenhouse gases. It is estimated that banning CFCs has avoided half a degree to one degree of global warming. An amendment to the Montreal Protocol, known as the Kigali Amendment, which was brought into force in 2016, was signed in Rwanda to control HFCs by 2030.
HFCs levels are still increasing but they are slowing down as countries take action.
It is estimated that controlling HFCs will save another half degree of greenhouse warming by the end of the century. “Because of the Montreal Protocol, those refrigerants that would have got into the atmosphere were not released,” says Robinson. “That’s the biggest effect of the Montreal Protocol.”
There’s more to it. A depleted ozone layer would allow much more UV radiation to reach the Earth, reducing plants’ ability to perform photosynthesis and resulting in much higher levels of CO2 in the atmosphere than we currently have.
“It has been a tremendous success,” says Robinson, who sits at the UNEP Environmental Effects Assessment Panel, which assesses the environmental effects of ozone depletion and its interactions with climate change.
“We have effectively reduced the warming that we would have otherwise had. The Montreal Protocol is probably our most successful climate warming treaty.”
Perception and interests
The severe depletion of the ozone layer was expected to increase skin cancer rates and harm crops. “Ozone depletion was such an existential threat,” Robinson remembers. “It captured everyone’s attention.”
“People were truly scared of it,” says Kate Crowley, Associate Professor of Public and Environmental Policy at the University of Tasmania and author of numerous books on Australian environmental policy. “For some reason, it’s hard to get across that we need to be scared of climate change now.”
“It has been far too slow,” agrees Wollongong’s Robinson, “But we’re getting to that stage where people say, enough is enough.” .
“The Montreal Protocol is probably our most successful climate warming treaty.”
Professor Sharon Robinson
Tackling the climate crisis isn’t as straightforward as solving the ozone layer issue.
The ozone problem was much easier to define and narrowly address. Only a few companies were involved in producing CFCs, and the solution – producing other compounds – meant they could stay in business. Global warming, Crowley says, is more complex.
To address the climate crisis, we must fundamentally restructure our societies. No doubt relying on coal, oil, and gas will hasten the problem. “That’s well understood. And it’s been well understood for some time,” she says. “But that comes to bang up against nations’ and global interests.”
She says that in Australia, entrenched political and economic interests have put the brakes on climate change action and that talks about economies being wrecked have thwarted attempts to set the agenda for change.
“For some reason, it’s hard to get across that we need to be scared of climate change now.”
Associate Professor Kate Crowley
However, the economic cost of ignoring climate change will far outweigh the cost of dealing with it. And the longer we wait, the higher the price will be. The floods, which killed almost two dozen people and ravaged Lismore in NSW, cost $9.6 billion. The 2019-20 Black Summer bushfires cost Australia nearly $100 billion.
“The cost of dealing with climate change was always a future problem. But now, it’s actually now,” says Crowley.
It takes time to untangle the ties between fossil fuel industry interests and politicians. But measures like outlawing political donations from fossil fuel companies in Australia and all other burning and exporting fossil fuels countries could free policymakers from vested interests.
Our ozone roof is still under threat
The UN report may not be the happy end of the ozone layer hole story. Human activities, natural and climate warming-driven disasters and some proposed solutions to the climate crisis could reverse some of the progress.
Rocket exhaust gases and particulates have been shown to damage the ozone layer. Yet, their impact on the atmosphere is neither regulated nor closely monitored.
The Black Summer megafires caused the largest stratospheric warming since Mount Pinatubo erupted in the Philippines in 1991. The fires created pyrocumulus clouds that pumped sulphur aerosols – potent ozone-depleting gases – into the stratosphere. University of Exeter’s researchers reported that the 2019-20 Australian fires played a significant role in extending the lifetime of the Antarctic ozone hole.
The UN report may not be the happy end of the ozone layer hole story.
Paradoxically, deliberately injecting sulphur aerosols into the stratosphere has been proposed as a geoengineering method for reversing global warming. Sulphur particles injected in the stratosphere reflect sunlight away from the Earth’s surface, cooling it. However, according to Robinson, an expanding hole in the ozone layer may set us up for more climate change issues.
“Reducing greenhouse gas emissions is the solution [to climate change]. We must get rid of them quickly rather than relying on quick fixes.
“We often underestimate how quickly we can move to a new state until we actually do it,” Robinson says.
“All the countries of the world can agree that something is too important to let it happen. We have one planet. It’s our home. It’s home to lots of other animals and plants. But it’s our home. If we want to protect it, we must change the way we live. We have done it in the past. We can do it again.”
Crowley agrees. “The success of the ozone layer is a good case study. It was a pretty terrifying global problem, but we solved it. We can reverse massive environmental problems. So let’s do it.”
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