Understanding the Contribution of Ozone Changes in the Historical Sea Level Change

• Main Authors: Rathore, S., Church, J., Zika, J., Zhang, X., Sohail, T.
• Format: Conference Object
• Language: English
• Published: 2023
• Subjects: Antarctic; Southern Ocean; The Antarctic; Antarctic Peninsula; Antarc*
• Online Access: https://gfzpublic.gfz-potsdam.de/pubman/item/item_5018904

Changes in sea level are mostly driven by internal climate variability, and anthropogenic forcing. Moreover, changes in stratospheric and tropospheric Ozone during the second-half of the 20th century also cause significant changes in ocean heat uptake. A recent study has shown that both stratospheric and tropospheric ozone have contributed to the Southern Ocean warming in the deep ocean. This study has shown that the 30% of Southern Ocean warming during 1955-2000 is driven by ozone in the upper 2000 m of the ocean. Of this 30%, 60% is attributed to stratospheric and 40% to tropospheric ozone changes. Changes in ocean heat uptake consequently affect sea level and we assess these changes due to ozone. From the analysis of four CMIP6 models with a total of 28 ensemble members, we find that thermosteric sea level increases between 40-60 S and decreases between 60 S and the Antarctic peninsula. Hence, there is a gradient in thermosteric sea level established around 60 S with higher sea level on the equatorward side and lower sea level on the poleward side. The increased sea level in the Southern Ocean is plausibly related to an increase in the strength of westerlies due to ozone forcing that has helped to deposit more heat due to the intense churning of the subtropical gyres. Further investigations are required to quantify the changes in sea level due to ozone in comparison to aerosols, greenhouse gases, and their combination (i.e., historical trend) to explain the observed sea level changes.