The study looked at how ozone levels in the upper stratosphere are affected by temperature changes, specifically focusing on the impact of chlorine. By analyzing data from different satellites over several years, the researchers found that as chlorine levels in the stratosphere increase, the sensitivity of ozone to temperature decreases. This sensitivity is expected to increase as chlorine levels decrease in the future. The study suggests that tracking these ozone-temperature correlations can help monitor the impact of chlorine on the stratosphere and assess the recovery process as chlorine is removed.