Restoration of the Ozone Layer Is Back on Track, Scientists Say

The protective ozone layer in the upper atmosphere could be restored within several decades, scientists said Monday, as recent rogue emissions of ozone-depleting chemicals from China have been largely eliminated. From a report: In a United Nations-sponsored assessment, the scientists said that global emissions of CFC-11, a banned chemical that has been used as a refrigerant and in insulating foams, had declined since 2018 after increasing for several years. CFC-11 and similar chemicals, collectively called chlorofluorocarbons, destroy ozone, which blocks ultraviolet radiation from the sun that can cause skin cancer and otherwise harm people and other living things. The scientists said that if current policies remained in place, ozone levels between the polar regions should reach pre-1980 levels by 2040. Ozone holes, or regions of greater depletion that appear regularly near the South Pole and, less frequently, near the North Pole, should also recover, by 2045 in the Arctic and about 2066 in Antarctica. "Things continue to trend in the right direction," said Stephen A. Montzka, a research chemist with the National Oceanic and Atmospheric Administration and one of the report's authors. Dr. Montzka led a 2018 study that alerted the world that CFC-11 emissions had been increasing since 2012 and that they appeared to come from East Asia. Investigations by The New York Times and others strongly suggested that small factories in Eastern China disregarding the global ban were the source. The new emissions had threatened to undermine the Montreal Protocol, the treaty negotiated in the 1980s to phase out the use of chlorofluorocarbons in favor of more benign chemicals after it was discovered that chlorofluorocarbons were depleting atmospheric ozone.

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