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How Scientists and The Montreal Protocol Saved Us from Catastrophe
How Scientists and The Montreal Protocol Saved Us from Catastrophe
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Where would we be without the ozone layer? Or indeed, would we be here at all?
Step back in time to around 2.4 billion years ago when the hellish atmosphere that had been early Earth, was about to take a different turn. The Great Oxygenation Event was a sharp rise in oxygen levels, due to photosynthetic bacteria expelling oxygen as a by-product. Leap forward to around 600 million years ago, when oxygen had reached high enough levels to sustain ozone in the upper atmosphere. This ozone layer protected Earth from ultraviolet radiation and enabled life to evolve and flourish. Ozone filters out harmful ultraviolet radiation and protects us from skin cancers and cataracts. Moreover, it protects fragile marine ecosystems and agricultural productivity. Take one last giant stride, to mankind and its industrial and technological advances, where this marvel of nature would be one of our greatest causes for concern. This in turn, led to the Montreal Protocol, a groundbreaking, worldwide agreement to save it.
Humans it seems, have always desired ever more ease and convenience and there’s pressure to provide this. In the 1930s, chlorofluorocarbons (CFCs) were developed. How wonderful it was to have a fine-misted aerosol to keep hairstyles in place, cleaning products that required less elbow-grease and of course, refrigeration. What more could we ask? At the time, who would have thought the chemicals in these products, among others, would make their way tens of miles into the upper atmosphere and start to break up something important called the ozone layer? Fortunately there were some scientists who did.
In 1970, Paul J. Krutzen, an atmospheric chemist, showed that nitrogen oxide produced through human activity, such as supersonic aeroplanes, could destroy ozone. This was crucial in understanding that the ozone layer was sensitive to certain chemical reactions. Around the same time, scientist James Lovelock, discovered that CFCs accumulated in the lower atmosphere (troposphere) and did not break down. Furthermore, Mario Molina and F. Sherwood Rowland, both chemists, proposed the question - If CFCs didn’t break down, what happened to them? They subsequently discovered that CFCs could reach the stratosphere, where interaction with ultraviolet radiation released chlorine atoms that destroyed ozone molecules. A single chlorine atom could break apart more than 100,000 ozone molecules. (In 1995, Krutzen, Molina & Sherwood Rowland were jointly awarded the Nobel Prize for their work and were instrumental in informing the policy makers for The Montreal Protocol).
Throughout the 1970s, there was growing concern about the impact of CFCs on the ozone layer within the scientific community. Despite mounting evidence, there remained debate and disagreement, with a number of scientists casting doubt on the severity of the findings. In addition, there was a backlash from the companies that produced CFCs. It wasn’t until the early 1980s, when Jonathan Shanklin a meteorologist with the British Antarctic Survey, observed that the density of ozone varies throughout the year and a ‘hole’ (an exceptionally depleted layer) formed over Antarctica every Spring. He also noted ozone levels had begun dropping consistently in the late 70s. Shanklin, with colleagues Brian Gardiner and Joe Farman published their findings. Now there was grave cause for concern.
In the 1980s, research into ozone-depleting substances (ODS) accelerated and under the auspices of the United Nations, the Vienna Convention for the Protection of the Ozone Layer was agreed. This marked the first formal acknowledgment of the issue by governments. Its aim was to establish guiding principles based on collaborative research into the impact on human health and the environment and to determine whether human activities were the definitive cause of depleting ozone. Although successful in its aims, the approach remained cautious and countries were not legally required to take control actions to protect the ozone layer.
Susan Solomon, an atmospheric chemist and her team progressed Shanklin’s work and discovered a definitive link between CFCs and the depleting ozone layer. Her findings showed chlorine monoxide in the stratosphere over Antarctica, which was the missing proof that CFCs were the cause.
With undisputed evidence adding to the extensive research, direct action was needed and in 1987, parties adopted the Montreal Protocol on Substances that Deplete the Ozone Layer which became enforceable on 1st January 1989. The Montreal Protocol became the first treaty to be ratified by every country in the world and by 2009, 98% of ODS had been phased out. It was a landmark achievement and endorsed by governments and environmentalists alike. It strengthened the Vienna Convention by adding more detailed commitments - requirements to amend the Protocol if new evidence and technology arises; fixed timelines, differing for developed and developing nations and a multilateral fund to support developing countries in reaching their targets.
In 1988, President Ronald Reagan issued a statement, ‘The Montreal Protocol is a model of cooperation. It is a product of the recognition and international consensus that ozone depletion is a global problem, …. It is the result of an extraordinary process of scientific study, negotiations among representatives of the business and environmental communities, and international diplomacy. It is a monumental achievement.’
Throughout the 1990s and into the 2000s, the production of CFCs continued to be successfully phased out. In response to new evidence, five further amendments have identified new chemicals to be phased out. These include HCFCs (hydrochlorofluorocarbons) which replaced CFCs, and most recently in the Kigali Agreement (2016), HFCs (hydrofluorocarbons) which are powerful greenhouse gases that cause global warming.
So where are we now? It is no longer in the media, but it hasn’t gone away. ODS can take up to 100 years to break down. According to The Scientific Assessment Panel of the Montreal Protocol, if we remain on the current, successful trajectory we can expect almost complete recovery of the ozone layer by mid 21st century.
Let us hope we don’t take a step backwards.
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https://www.unep.org/ozonaction/who-we-are/about-montreal-protocol https://ozonewatch.gsfc.nasa.gov/facts/hole_SH.html Nobelprize.org/prizes/chemistry/1995/press-release/?utm_source=chatgpt.com https://www.un.org/sustainabledevelopment/sustainable-development-goals/ https://www.state.gov/the-montreal-protocol-on-substances-that-deplete-the-ozone-layer https://www.bas.ac.uk/data/our-data/publication/the-ozone-layer/ https://www.bbc.co.uk/future/article/20220321-what-happened-to-the-worlds-ozone-hole
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