edu.ucar.opensky::articles:27205 UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact 2025-12-24T18:49:43.017880 ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data ISO 19115-2:2009(E) https://n2t.org/ark:/85065/d7h70m13 https://doi.org/10.5281/zenodo.10677018 https Related ComputationalNotebook #1 jweiffenbach/PlioMIP2-SouthernOcean https://doi.org/10.1594/PANGAEA.911847 https Related Dataset #1 Sea surface temperature anomalies for Pliocene interglacial KM5c (PlioVAR) https://doi.org/10.7265/efmz-2t65 https Related Dataset #2 NOAA/NSIDC Climate Data Record of Passive Microwave Sea Ice Concentration, Version 4 https://doi.org/10.7289/V5T72FNM https Related Dataset #3 NOAA Extended Reconstructed Sea Surface Temperature (ERSST), Version 5 https://doi.org/10.5065/D6RX99HX https Related Service #1 Cheyenne: SGI ICE XA Cluster Highly stratified mid-Pliocene Southern Ocean in PlioMIP2 2024-05-02T00:00:00Z publication https://n2t.org/ark:/85065/d7h70m13 https://doi.org/10.5194/cp-20-1067-2024 Weiffenbach, J. E. author Dijkstra, H. A. author von der Heydt, A. S. author Abe-Ouchi, A. author Chan, W. author Chandan, D. author Feng, R. author Haywood, A. M. author Hunter, S. J. author Li, X. author Otto-Bliesner, Bette author Peltier, W. R. author Stepanek, C. author Tan, N. author Tindall, J. C. author Zhang, Z. author UCAR/NCAR - Library publisher During the mid-Pliocene warm period (mPWP; 3.264-3.025 Ma), atmospheric CO2 concentrations were approximately 400 ppm, and the Antarctic Ice Sheet was substantially reduced compared to today. Antarctica is surrounded by the Southern Ocean, which plays a crucial role in the global oceanic circulation and climate regulation. Using results from the Pliocene Model Intercomparison Project (PlioMIP2), we investigate Southern Ocean conditions during the mPWP with respect to the pre-industrial period. We find that the mean sea surface temperature (SST) warming in the Southern Ocean is 2.8 degrees C, while global mean SST warming is 2.4 degrees C. The enhanced warming is strongly tied to a dramatic decrease in sea ice cover over the mPWP Southern Ocean. We also see a freshening of the ocean (sub)surface, driven by an increase in precipitation over the Southern Ocean and Antarctica. The warmer and fresher surface leads to a highly stratified Southern Ocean that can be related to weakening of the deep abyssal overturning circulation. Sensitivity simulations show that the decrease in sea ice cover and enhanced warming is largely a consequence of the reduction in the Antarctic Ice Sheet. In addition, the mPWP geographic boundary conditions are responsible for approximately half of the increase in mPWP SST warming, sea ice loss, precipitation, and stratification increase over the Southern Ocean. From these results, we conclude that a strongly reduced Antarctic Ice Sheet during the mPWP has a substantial influence on the state of the Southern Ocean and exacerbates the changes that are induced by a higher CO2 concentration alone. This is relevant for the long-term future of the Southern Ocean, as we expect melting of the western Antarctic Ice Sheet in the future, an effect that is not currently taken into account in future projections by Coupled Model Intercomparison Project (CMIP) ensembles. UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact PDF Text theme Resource Type 2016-01-01T00:00:00Z publication Copyright author(s). This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License. None eng geoscientificInformation