Study Traces First Ozone Depletion to 1957 Carbon Tetrachloride, Predating CFCs by Decades
Updated
Updated · Gizmodo · Jun 29
Study Traces First Ozone Depletion to 1957 Carbon Tetrachloride, Predating CFCs by Decades
2 articles · Updated · Gizmodo · Jun 29
Summary
1957 marks the earliest detectable ozone depletion in new modeling, with the first signal appearing in the tropical upper stratosphere rather than over Antarctica.
Carbon tetrachloride—not CFCs—best explains that early thinning, the study says, because the solvent was already rising from 1930s dry-cleaning and degreasing use while CFC use came later.
Susan Solomon and colleagues ran a 76-year atmospheric chemistry simulation asking what scientists would have seen if modern monitoring had existed in 1950.
The finding rewrites a timeline long tied to the 1985 Antarctic ozone-hole discovery, when Halley station data showed spring ozone had fallen to about two-thirds of earlier levels by 1984.
Researchers said the result strengthens the case for long-term monitoring even after CFC curbs and carbon tetrachloride restrictions under the 1990 Montreal Protocol.
We missed the first ozone-killing chemical for decades. What threats are we missing now?
The ozone layer's recovery is delayed. Is a loophole in a landmark treaty to blame?
Rethinking Ozone Depletion: New Evidence Reveals Carbon Tetrachloride’s Decades-Long Legacy and Policy Gaps
Overview
Recent research has revealed that carbon tetrachloride (CCl4), once widely used in industry, began damaging the ozone layer much earlier than previously thought. Starting in the 1960s, substantial CCl4 emissions from industrial processes entered the atmosphere. Because of its unique chemical properties—such as a long atmospheric lifetime and efficient breakdown into ozone-destroying chlorine radicals—CCl4 became a potent threat, leading to a measurable decline in stratospheric ozone by the 1970s. Earlier scientific tools were not advanced enough to detect CCl4’s specific impact, causing its role in early ozone depletion to be overlooked for decades.