Abstract. The international scientific assessment of ozone depletion is prepared every four years to support decisions made by the Parties to the Montreal Protocol. In each assessment an outlook of ozone recovery time is provided. The year when equivalent effective stratospheric chlorine (EESC) returns to the level found in 1980 is an important metric for the recovery of the ozone layer. Over the past five assessments, the expected date for the return of EESC to the 1980 level, for mid-latitudes, has been delayed, from year 2049 in the 2006 assessment to 2066 in the 2022 assessment, which represents a delay of 17 years over a 16-year assessment period. Here, we quantify the primary drivers that have delayed the expected EESC recovery date between each of these assessments. We find that by using identical EESC formulations the delay between the 2006 and 2022 assessment’s expected return of EESC to 1980 levels is shortened to 12.6 years. Of this delay, bank calculation methods account for ~4 years, changes in the assumed atmospheric lifetime for certain ODSs account for ~3.5 years, an under-estimate of the emission of CCl₄ accounts for ~3 years, and updated historical mole fraction estimates of ODSs account for ~1 year. Since some of the underlying causes of these delays are amenable to future controls (e.g. capture of ODSs from banks and limitations on future feedstock emissions), it is important to understand the reasons for the delays in expected recovery date of stratospheric halogens.

中文翻译：

---

平流层卤素水平回归 1980 年：2006 年至 2022 年臭氧评估的移动目标

摘要。每四年进行一次臭氧消耗国际科学评估，以支持《蒙特利尔议定书》缔约方做出的决定。在每次评估中都提供了臭氧恢复时间的展望。当量有效平流层氯 (EESC) 恢复到 1980 年水平的年份是臭氧层恢复的一个重要指标。在过去的五次评估中，中纬度地区 EESC 恢复到 1980 年水平的预期日期被推迟，从 2006 年评估的 2049 年推迟到 2022 年评估的 2066 年，这比 2022 年评估推迟了 17 年。评估期为16年。在这里，我们量化了在每次评估之间延迟 EESC 预期恢复日期的主要驱动因素。我们发现，通过使用相同的 EESC 公式，2006 年至 2022 年评估中 EESC 恢复到 1980 年水平的预期延迟缩短至 12.6 年。其中，银行计算方法约占 4 年，某些 ODS 的假设大气寿命变化约占 3.5 年，CCl ₄排放量的低估约占3 年，以及更新的历史摩尔分数估计值ODS 占约 1 年。由于这些延误的一些根本原因可以通过未来的控制（例如从库存中捕获消耗臭氧层物质和限制未来原料排放），了解平流层卤素预期回收日期延误的原因非常重要。