Ozone levels in the atmosphere vary due to both natural processes and human activities, and understanding how ozone may change in the future requires examining its past behavior. The first signs of Antarctic ozone depletion emerged in the late 1970s, largely driven by increasing concentrations of chlorine in the stratosphere. This depletion is now known to be caused predominantly by human-produced chlorofluorocarbons (CFCs). Following the discovery of the Antarctic ozone hole, the 1987 Montreal Protocol was adopted to phase out the production of chlorine- and bromine-containing ozone-depleting substances (ODSs). Stratospheric chlorine reached its peak in the early 2000s, reflecting the cumulative emissions of ODSs over previous decades. Since then, the measures implemented under the Montreal Protocol and its amendments have successfully reduced ODS levels, leading to a gradual decline in stratospheric chlorine after 2000 (Kuttippurath et al., 2017, 2018, 2021a). Polar ozone depletion occurs when chlorine is activated on the surfaces of polar stratospheric clouds (PSCs), which form under extremely cold conditions.

Although Arctic ozone losses were first identified in the early 1990s, quantifying chemical ozone depletion in this region is more challenging than in Antarctica because of stronger planetary‐wave activity (Kuttippurath et al., 2021b). Even so, studies consistently show that the most severe Arctic ozone losses occur during the coldest winters (such as those in 1995, 2011, and 2020), whereas warmer winters exhibit little to no depletion. Cold winters favor substantial ozone loss because they are characterised by a stable polar vortex, extensive formation of polar stratospheric clouds (PSCs), and elevated halogen concentrations (Goutail et al., 2005).

Earlier analyses suggested that total column ozone (TCO) trends in the Arctic are generally small and not statistically significant, primarily due to the region’s strong year-to-year dynamical variability. However, contemporary studies based on TCO measurements from multiple high-latitude monitoring stations indicate a significant positive trend in the Arctic (Pazmino et al., 2023). Similarly, investigations of the broader Northern Hemisphere (NH) stratosphere have also reported positive TCO trends there (Kuttippurath et al., 2023, 2024). Collectively, these findings underscore the need for a more comprehensive and methodologically consistent evaluation of Arctic ozone trends.

To address this research gap, we performed an extensive evaluation of TCO and vertical ozone distribution using multiple satellite and ground-based data covering the period 1988–2024. Employing a multiple linear regression framework, we estimated long-term trends and quantified the relative contributions of key dynamical and chemical drivers influencing the Arctic ozone. This approach enables a more robust characterisation of ozone evolution in the region and provides insights into the underlying processes governing its variability and potential recovery (Anjali and Kuttippurath, 2025).

Our analysis shows statistically significant positive trends in the upper-stratospheric ozone (5–1 hPa) and in TCO from both merged satellite and ground-based measurements since 2000. Ground-based records further indicate significant TCO increases at several southern Arctic stations during autumn and spring. Although these positive trends persist across multiple post-2000 periods, lower-stratospheric ozone profiles do not yet exhibit clear signs of recovery.

 References and related works: 

1. Anjali, S., Kuttippurath, J. Tracing the signatures of ozone recovery in the Arctic ozone. Sci Rep 15, 35304, https://doi.org/10.1038/s41598-025-19373-0, 2025.
2. Goutail, F. et al.: Early unusual Ozone loss during the Arctic winter 2002/2003 compared to other winters. Atmos. Chem. Phys. 5, 665–677, 2005.
3. Kuttippurath, J., G. S. Gopikrishnan, R. Mueller, S. Godin-Beekmann and J. Brioude: No severe ozone depletion in the tropical stratosphere in recent decades, Atmos. Chem. Phys., https://doi.org/10.5194/acp-24-6743-2024, 2024.
4. Kuttippurath, J., BR Sharma, GS Gopikrishnan: Trends and variability of Total Column Ozone in the Third Pole, Front. Clim., doi:10.3389/fclim.2023.1129660, 2023.
5. Kuttippurath, J., Feng, W., Müller, R., Kumar, P., Raj, S., Gopikrishnan, G. P., and Roy, R.: Exceptional loss in ozone in the Arctic winter/spring of 2019/2020, Atmos. Chem. Phys., doi: https://doi.org/10.5194/acp-21-14019-2021, 2021b.
6. Kuttippurath, J., F. Lefevre, S. Raj, P. Kumar, and K. Abbhishek: The ozone hole measurements at Maitri station in Antarctica, Polar Science, https://doi.org/10.1016/j.polar.2021.100701, 2021a.
7. Kuttippurath, J., P. Kumar, P. J. Nair, and P. C. Pandey: Emergence of ozone recovery evidenced by reduction in Antarctic ozone loss saturation, npj Clim. Atmos. Sci., 1:42, doi: 10.1038/s41612-018-0052-6, 2018. 
8. Kuttippurath, J. and P. J. Nair: The signs of Antarctic ozone recovery, Sci. Rep., doi: 10.1038/s41598-017-00722-7, 2017. 
9. Pazmiño, A. et al.: Trends in Polar Ozone loss since 1989: potential sign of recovery in the Arctic Ozone column. Atmos. Chem. Phys. 23, 15655–15670, 2023.