Is ozone depletion still a cause of concern?

Current state and its intertwining with climate change

2023 marked a celebratory year with the reports on healing of the ozone layer - it is on the path to recovery, if not fully restored. The recent report by scientists on the planetary boundaries1 framework published by the Stockholm Resilience Centre confirmed that the human perturbation of the stratospheric ozone depletion has decreased and is now within the safe operating space. Also, as per the UN Environment Programme, there is evidence that the ozone layer is healing itself and can recover by the middle of this century - the Antarctic ozone hole is expected to close by the 2060s, while other regions will return to pre-1980s values even earlier. Nearly 99 per cent of ozone-depleting substances have been phased out.

How was this possible? Let’s go back to one of the landmark agreements signed in the history of environmental treaties - the 1987 Montreal Protocol. With nearly 200 countries signing this agreement, it successfully preserved the ozone layer by prohibiting ozone-depleting substances (such as chlorofluorocarbons). It has already helped avert around 0.5 degrees Celsius of global warming. For humans, this has potentially helped to prevent up to two million cases of skin cancer globally each year by 2030 and resulted in an estimated US$1.8 trillion in health benefits, mostly in skin cancer treatment alone. There have been further developments to this Protocol with Kigali Agreement (2016) to reduce the consumption and production of Hydrofluorocarbon (potent greenhouse gas) which has already been signed by almost all member nations of the United Nations.

This made me think (considering the VUCA effect), are we patting ourselves on the back a bit too soon? It took 4 decades for the damage to be noticed and its reversal is taking much longer, as these ozone-depleting substances can live in the atmosphere for 50-100 years. Studies have found that the ozone layer is impacted by environmental variables. One such MIT study has highlighted that as long as these ozone-depleting substances persist in the atmosphere, large fires could spark a reaction that temporarily depletes the ozone layer. It was shown that the Australian wildfires widened the ozone hole by 10 percent in 2020. The Harvard researchers had in the past found that volcanic eruptions could result in ozone depletion until 2070 or beyond, despite declining concentrations of human-made chlorofluorocarbons. Nitrous oxide, a powerful greenhouse gas emitted from fertiliser applications in agriculture, is also a potent ozone-depleting substance which is not covered by the Montreal Protocol and its emissions are increasing. There is also a risk of resurgence in the emission of ozone-depleting pollutants as it is still being illicitly produced in some factories.

We all know that climate change is one of the global catastrophic risk our planet faces today. But does climate change exacerbate ozone-depletion? While ozone depletion is not a major cause of climate change, both are linked in a number of ways. Research shows that ozone is influenced by changes in the meteorological conditions and by changes in the atmospheric composition that could result from climate change. Climate change, including increased heat, extended drought, and a parched atmosphere, has been a key driver in increasing the risk and extent of wildfires in the past two decades. At the same time, global warming and especially heatwaves result in accelerated snowmelt and sea-ice loss, potentially adding UV radiation to the list of stressors that Antarctic organisms are already being exposed to. This relationship between climate change and ozone layer has the potential to create a reinforcing loop for ozone depletion.

Would this lead to the tipping point and breach the planetary boundary identified for ozone depletion?

Probably not. NASA has reported that negative changes in the ozone layer are being offset by positive changes in human behaviour, allowing the ozone layer to reform. However, to stay on track for ozone recovery, we need to amplify our actions on climate change. The Montreal Protocol has set an example that with global consensus, it is possible to avert global environmental issues. It has offered valuable lessons in terms of the need for early action, innovation, economic benefits, regulatory frameworks, public engagement, and adaptation. Also, as these issues are long-term and persist in the environment for decades, it is imperative to have sound scientific research and continuous monitoring to understand the problems, track progress, and adjust strategies accordingly. A sustainable future requires continued adherence to the Montreal Protocol, with particular attention to mitigation of climate change, which will also determine future UV radiation on the Earth’s surface.

I am hopeful that as awareness grows about the direct impact of climate change (immediate as well as long-term) not only on people’s quality of life but also for the global economy, and with unwavering support from the realms of science and politics, we would be better equipped to address, mitigate, and eventually reverse the challenges posed by this critical issue. We are on track to save the ozone; we can save our planet as well.

It is still not too late to act!

List of references:

UN: Preserving the Ozone Layer: https://www.un.org/en/climatechange/preserving-the-ozone-layer

Planetary Boundaries: https://www.stockholmresilience.org/research/planetary-boundaries.html

MIT News Office, Study: Smoke particles from wildfires can erode the ozone layer, March 8, 2023: https://news.mit.edu/2023/study-smoke-particles-wildfires-erode-ozone-0308

By Leah Burrows, How future volcanic eruptions will impact Earth’s ozone layer, August 16, 2017: https://seas.harvard.edu/news/2017/08/how-future-volcanic-eruptions-will-impact-earths-ozone-layer

NOAA: Wildfire climate connection, July 24, 2023, https://www.noaa.gov/noaa-wildfire/wildfire-climate-connection

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Author: Charmi Mehta, Student of MBA Sustainability Management Class 1 (2023-2025)