EGU25-14845, updated on 15 Mar 2025
https://doi.org/10.5194/egusphere-egu25-14845
EGU General Assembly 2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
Poster | Wednesday, 30 Apr, 16:15–18:00 (CEST), Display time Wednesday, 30 Apr, 14:00–18:00
 
Hall X5, X5.231
Positive low cloud feedback accelerates abrupt Southern Ocean sea-ice decline in high-resolution global climate model
Dae-Won Kim1,2, Martina Zapponini3, Sahil Sharma1,2, Thomas Jung3,4, Myeong-Hyeon Kim1,2, Nikolay Koldunov3, Navajyoth Puthiyaveettil1,2, Dimitry Sidorenko3, Jan Streffing3, Axel Timmermann1,2, Tido Semmler3,5, and Wonsun Park1,2
Dae-Won Kim et al.
  • 1Institute for Basic Science, Center for Climate Physics, Busan, 46241, Republic of Korea
  • 2Pusan National University, Busan, 46241, Republic of Korea
  • 3Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, 27570, Germany
  • 4Department of Physics and Electrical Engineering, University of Bremen, 28359, Bremen, Germany
  • 5Met Éireann, 65-67 Glasnevin Hill, D09 Y921, Dublin, Ireland

Sea ice extent around the Antarctic exhibits a high level of variability on interannual and longer timescales, characterized by a positive trend since the satellite era and interruptions due to e.g., the emergence of the Maud Rise Polynya in 2016. Given the relatively short period of observational data and the high level of natural variability it has remained challenging to unequivocally identify the anthropogenic fingerprint in Antarctic sea ice. Moreover, to properly study the Antarctic sea-ice and its response to future warming, it is necessary to capture important dynamics, such as polynyas, the Antarctic slope current and coastal leads. Many models within the CMIP6 model portfolio do not even have the spatial resolution to adequately resolve these features. This implies that their Antarctic projections may not be as trustworthy and robust as those for the Arctic Ocean.

In this study, we employ the high-resolution OpenIFS-FESOM (AWI-CM3) coupled general circulation (nominally 31 km atmosphere and 4-25 km ocean resolutions) to investigate the Antarctic sea ice response to greenhouse warming, following a SSP5-8.5 greenhouse gas emission scenario. Our simulation exhibits a sudden decline of Antarctic sea ice in the Weddell Sea (WS) which can be explained by a combination of physical processes that involve continued strengthening of westerlies, increasing of horizontal density and pressure gradients, intensifying of atmosphere-ocean momentum transfer due to sea ice decline, a spin-up of the cyclonic gyre and westward current and corresponding vertical and horizontal supply of heat into the Weddell Sea. The resulting decrease of sea ice further leads to heat accumulation in austral summer due to the absorption of short-wave radiation, which can further weaken winter sea ice extent and intensify the momentum transfer and associated heat transport into the Weddell Sea. 

Our study highlights the relevance of positive atmosphere-sea ice-ocean feedback in triggering the abrupt decline in Antarctic sea ice.  

How to cite: Kim, D.-W., Zapponini, M., Sharma, S., Jung, T., Kim, M.-H., Koldunov, N., Puthiyaveettil, N., Sidorenko, D., Streffing, J., Timmermann, A., Semmler, T., and Park, W.: Positive low cloud feedback accelerates abrupt Southern Ocean sea-ice decline in high-resolution global climate model, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14845, https://doi.org/10.5194/egusphere-egu25-14845, 2025.