New research from MIT shows that human-caused ozone depletion began decades earlier than previously thought. Using atmospheric models and ice core data, scientists found that carbon tetrachloride, a dry-cleaning chemical used since the 1930s, likely caused measurable ozone loss as early as 1957. The first signal would have appeared in the tropical upper stratosphere, not over Antarctica. This shifts the timeline of ozone damage well before the CFC era and the discovery of the Antarctic ozone hole in 1985. The study highlights the value of long-term atmospheric monitoring and ice core records. Carbon tetrachloride was largely phased out under the Montreal Protocol, but its early impact shows how industrial chemicals can affect the atmosphere for decades. Researchers stress that continued monitoring is essential to track recovery and catch unexpected changes. The findings reinforce why the Montreal Protocol remains a benchmark for global environmental agreements.
