AWI-LMU joint research group for Southern Ocean-Climate Interactions (SO-CLIM)
Earth System Models (ESM) do not yet depict observed climatic changes in the Southern Ocean adequately. (Graphic: A. Haumann)
Vision
Our group wants to raise awareness for the important role of the ocean in the Earth’s system and how it is changing to strengthen efforts to limit human influences on the ocean and climate. In particular, with our work, we want to understand the essential Southern Ocean’s role in mitigating global climate change in the past, present, and future, and how this highly sensitive region of our planet responds to climatic changes.
Background
The Southern Ocean strongly influences the global climate through its interaction with Earth’s carbon and energy budget. This important role arises from the vast exchange of water between the deep ocean and the sea surface that is unprecedented in the global ocean elsewhere. Over past decades, the Southern Ocean has substantially slowed global surface warming by absorbing most of the excess heat in the climate system and a large fraction of the anthropogenic carbon dioxide emissions. However, over the past years the Southern Ocean has experienced drastic changes and, to date, it remains uncertain if it will continue to slow down global surface warming in future to the extent that it has been providing such a service in the past.
Mission
While climate models make an important contribution to creating reliable information for decision-makers and society, they still do not represent past observed climatic changes in the Southern Ocean adequately, leading to considerable uncertainties in future projections. In part, these difficulties arise from the inherent challenge to collect observational data in this region and the associated knowledge gap. In our group, we collect and use observational data and deploy numerical models to better understand processes and changes in the Southern Ocean and thus contribute to improving regional and global projections with model simulations.
News
Ocean warming drives melting of Antarctic sea ice
A new study from Theo Spira et al. in Nature Climate Change reveals reasons for rapid sea ice decline since 2015
SO-CLIM Retreat at Schneefernerhaus
High above the clouds, where alpine landscapes meet cutting-edge science, the SO-CLIM team came together for an inspiring retreat at the Schneefernerhaus on the Zugspitze.
SO-CLIM Research Group in the western Weddell Sea
Alexander Haumann and Rowan Brown (SO-CLIM) are currently on a research expedition in the western Weddell Sea (Antarctica). They are investigating sea ice melt and water mixing processes, which are central to ocean circulation, carbon and heat fluxes.
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Low-salinity water in the Southern Ocean kept CO₂ locked…
Low-salinity water in the Southern Ocean kept CO₂ locked away for decades - New study reveals an overlooked oceanic carbon storage mechanism.
Lecture Regional Geography II: Oceans (winter semester) Advanced seminar: Polar Regions in Transition (winter semester) Short field trip: Heincke Expedition North Sea (summer semester)
Publications
Spira, T., du Plessis M., Haumann, F. A., Giddy, I., Narayanan, A., Silvanoo, S., Swart, S. (2026). Wind-triggered Antarctic sea-ice decline preconditioned by thinning Winter Water. Nature Climate Change. https://doi.org/10.1038/s41558-026-02601-4
Olivier, L., Haumann, F. A. (2025). Southern Ocean freshening stalls deep ocean CO2 release in a changing climate. Nature Climate Change. https://doi.org/10.1038/s41558-025-02446-3
Pan, B. J., Gierach, M. M., Stammerjohn, S., Schofield, O., Meredith, M. P., Reynolds, R. A., Vernet, M., Haumann, F. A., Orona, A. J., & Miller, C. E. (2025). Impact of glacial meltwater on phytoplankton biomass along the Western Antarctic Peninsula. Commun Earth Environ6, 456. https://doi.org/10.1038/s43247-025-02435-6
Stammerjohn, S., Eayrs, C., Haumann, F. A., Hobbs, W., Holland, M., Reid, P., Roach, L. A., & Smith, M. (2025). Antarctic Sea-Ice : Ongoing Changes and Compelling Issues. Antarctica and the Earth System, 115–140. https://doi.org/10.4324/9781003406471-6
Olivier, L., Boutin, J., Reverdin, G., Hunt, C., Linkowski, T., Chase, A., Haentjens, N., Junger, P. C., Pesant, S., & Vandemark, D. (2025). Exploring the CO2 fugacity along the east coast of South America aboard the schooner Tara, Earth Syst. Sci. Data, 17, 3583–3598. https://doi.org/10.5194/essd-17-3583-2025
Weinhart, A. H., Haumann, F. A., Robertson, E., Meyer, H., Marent, A., & Weiner, M. (2025). Seawater stable isotopes from the southeastern Atlantic during the GO-SHIP A13.5 2024 expedition [dataset]. PANGAEA. https://doi.org/10.1594/PANGAEA.981232
Silvano, A., Narayanan, A., Catany, R., Olmedo, E., González‐Gambau, V., Turiel, A., Sabia, R., Mazloff, M. R., Spira, T., Haumann, F. A., & Garabato, A. C. N. (2025). Rising surface salinity and declining sea ice: A new Southern Ocean state revealed by satellites. Proceedings of the National Academy of Sciences, 122(27). https://doi.org/10.1073/pnas.2500440122
Friedlingstein, P., O’Sullivan, M., Jones, M. W., Andrew, R. M., Hauck, J., Landschützer, P., Le Quéré, C., Li, H., Luijkx, I. T., Olsen, A., Peters, G. P., Peters, W., Pongratz, J., Schwingshackl, C., Sitch, S., Canadell, J. G., Ciais, P., Jackson, R. B., Alin, . . . Olivier, L., . . . Zeng, J. (2025). Global Carbon Budget 2024. Earth System Science Data, 17(3), 965–1039. https://doi.org/10.5194/essd-17-965-2025
Swart, N. C., Martin, T., Beadling, R., Chen, J., Danek, C., England, M. H., Farneti, R., Griffies, S. M., Hattermann, T., Hauck, J., Haumann, F. A., Jüling, A., Li, Q., Marshall, J., Muilwijk, M., Pauling, A. G., Purich, A., Smith, I. J., & Thomas, M. (2023). The Southern Ocean Freshwater Input from Antarctica (SOFIA) Initiative: scientific objectives and experimental design. Geoscientific Model Development, 16(24), 7289–7309. https://doi.org/10.5194/gmd-16-7289-2023
Silvano, A., Purkey, S., Gordon, A. L., Castagno, P., Stewart, A. L., Rintoul, S. R., Foppert, A., Gunn, K. L., Herraiz-Borreguero, L., Aoki, S., Nakayama, Y., Garabato, A. C. N., Spingys, C., Akhoudas, C. H., Sallée, J., De Lavergne, C., Abrahamsen, E. P., Meijers, A. J. S., Meredith, M. P., M. P., Zhou, S., . . . Haumann, F. A., . . . Lee, W. S. (2023). Observing Antarctic bottom water in the Southern Ocean. Frontiers in Marine Science, 10. https://doi.org/10.3389/fmars.2023.1221701
I am a climate scientist fascinated by the ocean, ice, polar regions and the global carbon and water cycles. In particular, I study the impact of changing freshwater fluxes and ice on the Southern Ocean in past, present and future climates and their linkages to global changes at the interface of observations and models.
I have loved snow and ice since I was little, which is why I wrote my doctoral thesis on Arctic permafrost. I then shifted my professional focus to management, organization, and communication in science, which has allowed me to help shape and coordinate many projects in the Arctic and Antarctic.
My aim is to better understand the ocean carbon sink and its changes, with a special focus on the Southern Ocean. I study how the physics of the ocean impact the return pathways of CO2 to the surface, and for this I particularly love using data acquired on sailboats.
I am interested in the large-scale ocean circulation of the Southern Ocean and its impact on heat, freshwater and other physical properties. I am especially interested in understanding the interactions between different length- and time- scales of physical processes that drive ocean patterns and behaviour. In particular, I focus on in situ autonomous measurements from Argo floats.
I am an oceanographer with a passion for the high latitudes. My goal is to use non-hydrostatic models to improve our understanding of convection in the Southern Ocean, with the ultimate aim of improving how Southern Ocean convection is represented in global couple climate models.
In a study project, I want to look at the influence of Antarctic meltwater input on the upper cell of the global meridional overturning circulation using model data.
I am especially interested in physical processes in the high latitudes and their impact on the climate system. In my Master’s thesis, I investigate how surface-driven supercooling impacts properties of the upper Southern Ocean. For this purpose, I am implementing a novel approach to model surface-driven supercooling in an ocean model.
I want to understand the physical controls behind nutrient supply to the South Georgia phytoplankton bloom using high resolution in-situ observations across the ACC.
SO-SIMBA is an ESA-funded collaboration between institutes in Germany, Norway, France, Canada, and the United Kingdom that will develop and validate novel methods and satellite remote sensing products to quantify Antarctic sea ice mass balance.
MASIS intends to remedy the current issues of data collection, quality control, and compilation of stable isotopes in seawater, as well as to improve international networking and a varying degree of national capacity. We will assess the validation stage of the available datasets, as well as corresponding metadata and where and how they are communicated.
The SOFIA Initiative aims to improve our understanding of the simulated response to Antarctic freshwater input, and in particular the model uncertainty. The initiative was started by the CliC/CLIVAR/SCAR Southern Ocean Regional Panel, is endorsed as a CLIVAR task team, and has been submitted as a community MIP to CMIP7.
