By Eleanor Dann –
A potential threat to the recovery of the ozone hole has been discovered[1]. There is evidence to suggest new emissions of the chemical CFC-11, which may be due to an unreported production[2] and has the potential to delay the recovery of the ozone hole. This article explores the potential impact of these new emissions, as investigated by Dhomse et al.(2019)[1].
Figure 1: An image showing the ozone hole over Antarctica in 1979 and 2008. NASA, Public domain, via Wikimedia Commons.
But first, what is ozone and why is it so important? Ozone is a gas in our atmosphere, and when it is in the upper part of the atmosphere (the stratosphere) it forms an ‘ozone layer’ that protects us from harmful UV radiation[3]. However, it is being threatened by chemicals called chlorofluorocarbons (CFCs to you and me). These pollutants reduce the amount of ozone in the ozone layer, leading to an ozone hole in places like Antarctica[4]. Less ozone has increased likelihood of crop damage, cataracts and even cancer[5], so it is vital that we protect it.
After discovering the effect that CFCs have on the ozone layer, the world worked together to produce the Montreal Protocol, which tries to reduce the amount of CFCs in the atmosphere by stopping their production. It is perhaps one of the most successful international treaties to date, having been ratified by every single country in the world[6]; and it’s working, too. Evidence suggests that the ozone hole is recovering[1].
However, new emissions of CFC-11 may threaten this recovery. Using a computer model and comparing their simulations with satellite data from NASA, Dhomse et al.[1] calculated the possible impact of the new CFC-11 emissions. As you can see in Figure 1, they found that by 2050 the relative recovery of the ozone hole would be about 58% without these new emissions. With them, however, the recovery may be around 54%[1]. While this may not seem like a big difference, we know how important ozone is for the health of people and the environment. If this production stops, the delay in recovery will only be a few years[1], but if it carries on the impacts could be more devastating. Despite this, due to the success of the Montreal Protocol and the way that it has been enforced, the authors assumed that the new production of CFC-11 would not continue indefinitely, but stop in 5-20 years[1].
To conclude, while any delay to the recovery of the ozone hole is a potential cause for concern, the amount of ozone in the stratosphere is increasing, and the ozone hole is recovering[1]. The overwhelming success of the Montreal Protocol is definitely something that should be celebrated.
References and further reading:
[1]: Dhomse, S.S., Feng, W., Montzka, S.A., Hossaini, R., Keeble, J., Pyle, J.A., Daniel, J.S., Chipperfield, M.P. (2019) Delay in recovery of the Antarctic ozone hole from unexpected CFC-11 emissions. Nat Commun, 10, 1-12.
[2]: Montzka, S.A., Dutton, G.S., Yu, P., Ray, E., Portmann, R.W., Daniel, J.S., Kuijpers, L., Hall, B.D., Mondeel, D., Siso, C., Nance, J.D., Rigby, M., Manning, A.J., Hu, L., Moore, F., Miller, B.R., Elkins, J.W. (2018) An unexpected and persistent increase in global emissions of ozone-depleting CFC-11. Nature, 557, 413–417.
[3]: United States Environmental Protection Agency (n.d.) What is Ozone? https://www.epa.gov/ozone-pollution-and-your-patients-health/what-ozone [02.12.21].
[4]: NASA (2004) Ozone: What is it, and why do we care about it? https://www.nasa.gov/audience/foreducators/postsecondary/features/F_Ozone.html [02.12.21].
[5]: United States Environmental Protection Agency (n.d.) Health and Environmental Effects of Ozone Layer Depletion. https://www.epa.gov/ozone-layer-protection/health-and-environmental-effects-ozone-layer-depletion[02.12.21].
[6]: United Nations Environment Programme (n.d.) About Montreal Protocol. https://www.unep.org/ozonaction/who-we-are/about-montreal-protocol [02.12.21].
