An international team led by MIT scientists has identified higher-than-expected leakage from industrial feedstock chemicals as a key factor slowing the ozone layer's recovery. Their analysis estimates this could delay return to 1980 levels by up to seven years, from 2066 to 2073. Researchers urge tighter controls under the Montreal Protocol to address the issue.
The 1987 Montreal Protocol has driven a global phaseout of most ozone-depleting substances, enabling the ozone layer to heal after damage from chemicals like chlorofluorocarbons used in refrigeration and aerosols. However, the treaty permits these substances as feedstocks for producing plastics and coatings, assuming minimal atmospheric escape of about 0.5% during manufacturing. Recent atmospheric measurements challenge this, revealing leakage rates closer to 3.6% for some chemicals, tracked by networks like the Advanced Global Atmospheric Gases Experiment (AGAGE). Susan Solomon, Lee and Geraldine Martin Professor of Environmental Studies and Chemistry at MIT, described the feedstocks as 'a bug in the system,' noting production of ozone-depleting substances has nearly ceased worldwide except for this use. The study, published in Nature Communications by Stefan Reimann of the Swiss Federal Laboratories for Materials Science and Technology and colleagues from MIT, NASA, NOAA and others, modeled scenarios through 2100. With current leakage, total emissions stabilize around 2045 before a slow decline, pushing ozone recovery to 2073. Reducing leakage to 0.5% or eliminating emissions could restore 1980 conditions by 2066 or 2065. Stefan Reimann, the study's lead author, emphasized the need to reduce emissions through better processes, chemical swaps or reduced feedstock use. 'This paper sends an important message that these emissions are too high,' he said. Solomon expressed optimism about industry innovation, highlighting alternatives already available and past successes in tightening processes via monitoring data. Parties to the Montreal Protocol, involving 197 countries and the European Union, discuss such issues annually, with feedstock emissions already on the agenda.
