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By Vivek Saini
Claim 1: There’s no need to repair the ozone hole because there is no proof we caused the hole.
Fact 1: Misinformation. There is substantial scientific evidence linking human activities, particularly the release of chlorofluorocarbons (CFCs) and other ozone-depleting substances, to the depletion of the ozone layer.
Claim 2: A new Ozone hole is developing over the entire tropical region of the earth, seven times bigger than the south pole hole.
Fact 2: The Study that discovered a large ozone hole over the tropics generated several critical reactions from leading climate scientists worldwide. The study drew multiple solid rejections from the scientific community across the globe, stating that the study findings do not convince them as it couldn’t provide the mechanism that could explain the ozone hole.
Claim post:
What does the post say
In his viral X post, John Shewchuk @_ClimateCraze claimed there’s no need to repair the ozone hole formed over the south pole (Antarctic region) because no evidence supports that humans created the hole. He also claimed in his tweet that there’s another big hole created over the entire tropical area of Earth. He shared an image along with the tweet that says, “A new ozone hole is developing over the tropics, which is seven times bigger than the south pole hole.”
What we found
Scientific consensus overwhelmingly supports the idea that human activities, particularly the release of chlorofluorocarbons (CFCs) and other ozone-depleting substances, were responsible for the depletion of the ozone layer and the formation of the ozone hole. It has developed because people have polluted the atmosphere with chemicals containing chlorine and bromine. The primary chemicals involved are chlorofluorocarbons, halons, and carbon tetrachloride.
The other Claim made by the X (formerly Twitter) user is based on the controversial study released on July 5, 2022, in the journal AIP Advances. The article underwent the journal’s customary peer-review procedure but received little support and drew multiple rejections from most scientists worldwide. After experts refuted the claim made by the study, The deputy editor of the AIP Advances, A. T. Charlie Johnson, said, “We encourage readers and researchers to contact the authors whenever possible to discuss potential technical deficiencies of the study so that they may be addressed in corrections in the literature or comments and responses.”
Redefining the ozone hole
Most ozone is found in the stratosphere, an atmospheric layer 6 to 31 miles (10 to 50 km) above the planet’s surface. There, the gas functions like sunscreen, protecting Earth from the sun’s intense ultraviolet (UV) rays. According to NASA’s Earth Observatory, scientists discovered in the 1980s that long-lived atmospheric pollutants known as chlorofluorocarbons (CFCs) break down into chlorine and bromine when exposed to UV light beyond the ozone layer. These reactive substances rip O3 molecules apart, thinning out areas of the ozone layer and creating “holes,” mainly over Antarctica, where the freezing air conditions allow ozone-shredding reactions to occur quickly.
The Total Ozone Mapping Spectrometer (TOMS) of the National Aeronautics and Space Administration (NASA) calculated the ozone concentration in 1979. It defined an ozone hole as a region where the concentration of ozone molecules falls below 220 Dobson Units (DU).
The research study proposes a new approach and modeling tool for defining an ozone hole based on the percentage loss of ozone concentration over a particular area. In this case, the reference value is the ozone concentration in the 1960s, when very few fluorinated chemicals were released into the atmosphere. An ozone hole occurs when the concentration declines by 25% or more from the reference value. Furthermore, the author claims that the original data does not capture the tropical ozone hole.
An ozone hole occurs when the concentration falls by 25% or more of the reference value. Furthermore, the author claims that the original data cannot capture the tropical ozone hole. One of the problems with establishing a new definition of an ozone hole is that it is spectacular. In the 1970s, an ozone hole was developed to portray the terrible impact of UV rays caused by the ‘thinning’ of the layer.
Experts are unconvinced
The scientific community responded to the study strongly. There is no “tropical ozone hole,” according to Paul Young, a Lancaster University researcher specialising in scientific evaluations of ozone depletion. He noted that it is widely known that both naturally occurring processes and human-driven activities contribute to the long-term alterations and yearly fluctuation of the ozone layer in the tropical lower stratosphere (about 15 to 20 km up).
Dr Martha Alvarez, a different researcher from the University of Madrid, disagreed with the findings, claiming that the Brewer-Dobson circulation’s acceleration is mostly to blame for the tropics’ ongoing ozone loss, which is nothing new.
Professor Martyn Chipperfield of atmospheric chemistry at the University of Leeds was similarly dubious of the study since it didn’t offer a solid mechanism to support the author’s claim that there had been a significant ozone loss.
Concerns have also been raised about using a 1960s dataset that was created using model reconstructions but lacked evidence-based observations. This makes the findings much more troubling.
Professor Susan Solomon, a renowned expert in climate science at the Massachusetts Institute of Technology, acknowledges that research should be done on the tropical ozone decrease. She is not persuaded by the study’s assertion that an ozone hole exists over the tropics, though. She attributes ozone loss to natural occurrences like stratospheric winds.
Protecting the Ozone layer: What have we done so far
A significant ozone hole over Antarctica was first identified by scientists in the 1970s, which led to a global course correction. The Montreal Protocol, an international agreement to gradually phase out ozone-depleting compounds like chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) and thereby prevent any additional damage to the ozone layer, was developed in response to the impending existential threat to all life. The convention has been widely endorsed, ratified, and implemented since it entered force in 1989. CFCs and HCFCs are prohibited from being produced and imported in countries like the United States and the European Union, and the current supply of HCFCs is anticipated to be phased out by 2030.
The Kigali Amendment to the Montreal Protocol has expanded the treaty’s scope by recognising the effects of greenhouse gasses with a high global warming potential (GWP), such as HFCs. Globally, significant efforts are being made to reduce the production and use of HFCs by the Kigali Amendment, such as the European F-gas regulation and Singapore’s green labeling program (which informs consumers of the refrigerant used in their air conditioners).
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References:
- https://aip.scitation.org/doi/10.1063/5.0094629
- https://www.space.com/new-hole-in-ozone-layer-debunked
- https://earthobservatory.nasa.gov/world-of-change/Ozone
- https://eospso.nasa.gov/missions/total-ozone-mapping-spectrometer-earth-probe
- https://www.sciencemediacentre.org/expert-reaction-to-research-claiming-ozone-hole-over-tropics/
- https://agupubs.onlinelibrary.wiley.com/doi/10.1002/2013RG000448
- https://www.downtoearth.org.in/news/climate-change/does-tropical-ozone-hole-exist-experts-are-divided-83745
- https://www.downtoearth.org.in/news/climate-change/does-tropical-ozone-hole-exist-experts-are-divided-83745
- https://web.archive.org/web/20141008112902/http://ozone.unep.org/new_site/en/treaty_ratification_status.php
- https://www.epa.gov/ods-phaseout
- https://www.eea.europa.eu/ims/consumption-of-ozone-depleting-substances
- https://www.nea.gov.sg/our-services/climate-change-energy-efficiency/climate-change/reducing-ghg-emissions-from-the-use-of-refrigerants-in-rac-sector
