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by J. BESL<\/a><\/strong> MAY 29, 2023 (yaleclimateconnections.org)<\/p>\n\n\n\n![\"An](\"https:\/\/i0.wp.com\/yaleclimateconnections.org\/wp-content\/uploads\/2023\/05\/0523_Ozone_1600.jpg?fit=1200%2C675&ssl=1\")
In 1985, the British Antarctic Survey alerted the world that in the atmosphere high above the South Pole a giant hole was forming in the Earth\u2019s protective ozone layer. World leaders swiftly assembled to work out a solution. Two years later, the United Nations agreed to ban the chemicals responsible for eroding the layer of the stratosphere that shields Earth from the sun\u2019s ultraviolet radiation. Known as the Montreal Protocol agreement, it is still one of the UN\u2019s most widely ratified treaties.<\/p>\n\n\n\n
The Montreal Protocol was a win for diplomacy and the stratosphere. But unbeknown to its signatories at the time, the agreement was also an unexpected ward against climate catastrophe. As new research<\/a> shows, the aptly named ozone-depleting substances that created the hole over Antarctica are also responsible for causing 30 percent of the temperature increase we saw globally from 1955 to 2005.<\/p>\n\n\n\n The climate is changing, and our journalists are here to help you make sense of it. Sign up for our weekly email newsletter and never miss a story.<\/em><\/p>\n\n\n\n Michael Sigmond, a climate scientist at Environment and Climate Change Canada is the lead author of a new study calculating the greenhouse-trapping potency of ozone-depleting substances. The substances\u2019 contribution to global warming are, he says, \u201clarger than most people have realized.\u201d<\/p>\n\n\n\n Read: The best climate news you may not have heard about<\/a><\/em><\/p>\n\n\n\n Read: Checklist: How to take advantage of brand-new clean energy tax credits<\/a><\/em><\/p>\n\n\n\n The Montreal Protocol regulates nearly 100<\/a> ozone-eating chemicals. Many fall under the umbrella of chlorofluorocarbons, commonly called CFCs, chemicals popularized in the 1930s for use in spray cans, plastic foams, and refrigeration. Compared with the array of toxic, flammable alternatives they replaced, CFCs were seen as wonder chemicals, and by the early 1970s, the world was producing nearly one million tonnes of them each year.<\/p>\n\n\n\n <\/a><\/p>\n\n\n\n CFCs are inert, so they don\u2019t react with other gases. Instead, they tend to accumulate in the atmosphere and drift wherever the wind takes them, hanging around in the air for 85 years<\/a> or more. Once they reach the stratosphere, the second layer of Earth\u2019s multilayered atmosphere, CFCs begin to break down. They\u2019re \u201cdestroyed by being blasted apart by photons,\u201d explains Dennis Hartmann, a climate scientist at the University of Washington who was not involved in the research. That reactive ruckus is what causes the hole in the ozone layer.<\/p>\n\n\n\n In the troposphere \u2014 the lowest level of the atmosphere, which fewer photons reach \u2014 ozone-depleting substances act as long-lasting greenhouse gases. Back in 1987, scientists knew ozone-depleting substances trapped some solar radiation, but they didn\u2019t know how much. Only recently<\/a> have scientists been putting together the evidence that ozone-depleting substances are actually one of the most damaging warming agents of the past half century.<\/p>\n\n\n\n The effects of this warming are amplified at the poles. Sigmond and his colleagues\u2019 work shows that if ozone-depleting substances had never been mass produced \u2014 if the concentration in the atmosphere had stayed at 1955 levels \u2014 the Arctic today would be at least 55 percent cooler, and there\u2019d be 45 percent more sea ice each September.<\/p>\n\n\n\n Ozone-depleting substances production leveled off in the 1990s. But because they\u2019re so long-lived, these gases are still kicking around, and the warming they cause is still increasing. Yet it could have been much worse. By banning ozone-depleting substances, the Montreal Protocol unintentionally prevented 1\u00b0C of warming<\/a> by 2050.<\/p>\n\n\n\n With the Montreal Protocol, world leaders rallied around an urgent cause. In the process, we inadvertently phased out the second-largest forcer of global warming. The unanticipated benefits for the global climate, says Susann Tegtmeier, an atmospheric scientist at the University of Saskatchewan who was not involved in the study, \u201ccan be considered a very welcome and very positive side effect.\u201d<\/p>\n\n\n\n While it\u2019s taken a lot more negotiation and innovation to begin dislodging the main driver of climate change \u2014 carbon dioxide \u2014 the Montreal Protocol proves the power of collective action and shows how tackling environmental woes can help us in ways we didn\u2019t expect.<\/p>\n\n\n\n This story was originally published in Hakai Magazine<\/a> and is part of Covering Climate Now<\/a>, a global journalism collaboration strengthening coverage of the climate story.<\/em><\/p>\n","protected":false},"excerpt":{"rendered":" With the Montreal Protocol, life on Earth dodged a bullet we didn\u2019t even know was headed our way. by J. BESL MAY 29, 2023 (yaleclimateconnections.org) In 1985, the British Antarctic Survey alerted the world that in the atmosphere high above the South Pole a giant hole was forming in the Earth\u2019s protective… Continue reading ![\"\"](\"https:\/\/i0.wp.com\/yaleclimateconnections.org\/wp-content\/uploads\/2023\/05\/523_OzoneHole.jpeg?resize=780%2C780&ssl=1\")