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 ODSs. The substances\u2019 contribution to global warming are, he says, \u201clarger than most people have realized.\u201d<\/p>\n
The Montreal Protocol regulates nearly 100<\/a> ozone-eating chemicals. Many fall under the umbrella of chlorofluorocarbons (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 The world has phased out nearly 99 percent of ozone-depleting substances since the signing of the 1987 Montreal Protocol. The graphic shows in red the pockets of low ozone in 2019. While the situation is much improved since the worst levels in the 1990s and 2000s, the United Nations says the ozone hole over Antarctica won\u2019t heal until 2066. Photo by NASA Earth Observatory<\/p><\/div>\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 In the troposphere\u2014the lowest level of the atmosphere, which fewer photons reach\u2014ODSs act as long-lasting greenhouse gases. Back in 1987, scientists knew ODSs trapped some solar radiation, but they didn\u2019t know how much. Only recently<\/a> have scientists been putting together the evidence that ODSs are actually one of the most damaging warming agents of the past half century.<\/p>\n The effects of this warming are amplified at the poles. Sigmond and his colleagues\u2019 work shows that if ODSs had never been mass produced\u2014if the concentration in the atmosphere had stayed at 1955 levels\u2014the Arctic today would be at least 55 percent cooler, and there\u2019d be 45 percent more sea ice each September.<\/p>\n![\"\"](\"https:\/\/hakaimagazine.com\/wp-content\/uploads\/body-910-montreal-protocol-900x900.jpg\")
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