• Eayrs, C., Li, X., Raphael, M. N. & Holland, D. M. Rapid decline in Antarctic sea ice in recent years hints at future change. Nat. Geosci. 14, 460–464 (2021).

    Article 
    CAS 

    Google Scholar
     

  • Hobbs, W. et al. Observational evidence for a regime shift in summer Antarctic sea ice. J. Clim. 37, 2263–2275 (2024).

    Article 

    Google Scholar
     

  • Purich, A. & Doddridge, E. W. Record low Antarctic sea ice coverage indicates a new sea ice state. Commun. Earth Environ. 4, 314 (2023).

    Article 

    Google Scholar
     

  • Raphael, M. N. & Handcock, M. S. A new record minimum for Antarctic sea ice. Nat. Rev. Earth Environ. 3, 215–216 (2022).

    Article 

    Google Scholar
     

  • Holland, P. R. & Kwok, R. Wind-driven trends in Antarctic sea-ice drift. Nat. Geosci. 5, 872–875 (2012).

    Article 
    CAS 

    Google Scholar
     

  • Blanchard-Wrigglesworth, E., Roach, L. A., Donohoe, A. & Ding, Q. Impact of winds and Southern Ocean SSTs on Antarctic sea ice trends and variability. J. Clim. 34, 949–965 (2021).

    Article 

    Google Scholar
     

  • Bintanja, R., van Oldenborgh, G. J., Drijfhout, S. S., Wouters, B. & Katsman, C. A. Important role for ocean warming and increased ice-shelf melt in Antarctic sea-ice expansion. Nat. Geosci. 6, 376–379 (2013).

    Article 
    CAS 

    Google Scholar
     

  • Roach, L. A. et al. Winds and meltwater together lead to Southern Ocean surface cooling and sea ice expansion. Geophys. Res. Lett. 50, e2023GL105948 (2023).

    Article 

    Google Scholar
     

  • Haumann, F. A., Gruber, N. & Münnich, M. Sea-ice induced Southern Ocean subsurface warming and surface cooling in a warming climate. AGU Adv. 1, e2019AV000132 (2020).

    Article 

    Google Scholar
     

  • Lecomte, O. et al. Vertical ocean heat redistribution sustaining sea-ice concentration trends in the Ross Sea. Nat. Commun. 8, 258 (2017).

    Article 

    Google Scholar
     

  • Bocquet, M., Fleury, S., Rémy, F. & Piras, F. Arctic and Antarctic sea ice thickness and volume changes from observations between 1994 and 2023. J. Geophys. Res. Oceans 129, e2023JC020848 (2024).

    Article 

    Google Scholar
     

  • Turner, J. et al. Unprecedented springtime retreat of Antarctic sea ice in 2016. Geophys. Res. Lett. 44, 6868–6875 (2017).

    Article 

    Google Scholar
     

  • Fogt, R. L., Sleinkofer, A. M., Raphael, M. N. & Handcock, M. S. A regime shift in seasonal total Antarctic sea ice extent in the twentieth century. Nat. Clim. Change 12, 54–62 (2022).

    Article 

    Google Scholar
     

  • Zhang, L. et al. The relative role of the subsurface Southern Ocean in driving negative Antarctic sea ice extent anomalies in 2016–2021. Commun. Earth Environ. 3, 302 (2022).

    Article 

    Google Scholar
     

  • Diamond, R., Sime, L. C., Holmes, C. R. & Schroeder, D. CMIP6 models rarely simulate Antarctic winter sea-ice anomalies as large as observed in 2023. Geophys. Res. Lett. 51, e2024GL109265 (2024).

    Article 

    Google Scholar
     

  • Mohrmann, M., Heuzé, C. & Swart, S. Southern Ocean polynyas in CMIP6 models. Cryosphere 15, 4281–4313 (2021).

    Article 

    Google Scholar
     

  • Roach, L. A. et al. Antarctic sea ice area in CMIP6. Geophys. Res. Lett. 47, e2019GL086729 (2020).

    Article 

    Google Scholar
     

  • Suryawanshi, K., Jena, B., Bajish, C. & Anilkumar, N. Recent Ddecline in Antarctic sea ice cover from 2016 to 2022: insights from satellite observations, argo floats, and model reanalysis. Tellus 75, 193–212 (2023).


    Google Scholar
     

  • Meehl, G. A. et al. Sustained ocean changes contributed to sudden Antarctic sea ice retreat in late 2016. Nat. Commun. 10, 14 (2019).

    Article 
    CAS 

    Google Scholar
     

  • Stewart, K. D. & Haine, T. W. N. Thermobaricity in the transition zones between alpha and beta oceans. J. Phys. Oceanogr. 46, 1805–1821 (2016).

    Article 

    Google Scholar
     

  • Roquet, F., Ferreira, D., Caneill, R., Schlesinger, D. & Madec, G. Unique thermal expansion properties of water key to the formation of sea ice on Earth. Sci. Adv. 8, eabq0793 (2022).

    Article 

    Google Scholar
     

  • Abernathey, R. P. et al. Water-mass transformation by sea ice in the upper branch of the Southern Ocean overturning. Nat. Geosci. 9, 596–601 (2016).

    Article 
    CAS 

    Google Scholar
     

  • Morioka, Y. et al. Antarctic sea ice multidecadal variability triggered by Southern Annular Mode and deep convection. Commun. Earth Environ. 5, 633 (2024).

    Article 

    Google Scholar
     

  • Silvano, A. et al. Rising surface salinity and declining sea ice: a new Southern Ocean state revealed by satellites. Proc. Natl Acad. Sci. USA 122, e2500440122 (2025).

    Article 
    CAS 

    Google Scholar
     

  • Narayanan, A. et al. Zonal distribution of circumpolar deep water transformation rates and its relation to heat content on Antarctic shelves. J. Geophys. Res. Oceans 128, e2022JC019310 (2023).

    Article 

    Google Scholar
     

  • Talley, L. Closure of the global overturning circulation through the Indian, Pacific, and Southern oceans: schematics and transports. Oceanography 26, 80–97 (2013).

    Article 

    Google Scholar
     

  • Toole, J. M. Sea ice, winter convection, and the temperature minimum layer in the Southern Ocean. J. Geophys. Res. Oceans 86, 8037–8047 (1981).

    Article 

    Google Scholar
     

  • Spira, T., Swart, S., Giddy, I. & du Plessis, M. The observed spatiotemporal variability of Antarctic Winter Water. J. Geophys. Res. Oceans 129, e2024JC021017 (2024).

    Article 

    Google Scholar
     

  • Gordon, A. L. & Huber, B. A. Southern Ocean winter mixed layer. J. Geophys. Res. Oceans 95, 11655–11672 (1990).

    Article 

    Google Scholar
     

  • Pellichero, V., Sallée, J.-B., Schmidtko, S., Roquet, F. & Charrassin, J.-B. The ocean mixed layer under Southern Ocean sea-ice: seasonal cycle and forcing. J. Geophys. Res. Oceans 122, 1608–1633 (2017).

    Article 

    Google Scholar
     

  • Giddy, I. S., Fer, I., Swart, S. & Nicholson, S.-A. Vertical convergence of turbulent and double-diffusive heat flux drives warming and erosion of Antarctic Winter Water in summer. J. Phys. Oceanogr. 53, 1941–1958 (2023).

    Article 

    Google Scholar
     

  • Sabu, P. et al. Winter Water variability in the Indian Ocean sector of Southern Ocean during austral summer. Deep Sea Res. Pt. II 178, 104852 (2020).

    Article 

    Google Scholar
     

  • Lucas, N. S. et al. Giant iceberg meltwater increases upper-ocean stratification and vertical mixing. Nat. Geosci. 18, 305–312 (2025).

    Article 
    CAS 

    Google Scholar
     

  • Wilson, E. A., Bonan, D. B., Thompson, A. F., Armstrong, N. & Riser, S. C. Mechanisms for abrupt summertime circumpolar surface warming in the Southern Ocean. J. Clim. 36, 7025–7039 (2023).

    Article 

    Google Scholar
     

  • van der Boog, C. G., Dijkstra, H. A., Pietrzak, J. D. & Katsman, C. A. Double-diffusive mixing makes a small contribution to the global ocean circulation. Commun. Earth Environ. 2, 46 (2021).

    Article 

    Google Scholar
     

  • Shibley, N. C., Timmermans, M.-L., Carpenter, J. R. & Toole, J. M. Spatial variability of the Arctic Ocean’s double-diffusive staircase. J. Geophys. Res. Oceans 122, 980–994 (2017).

    Article 

    Google Scholar
     

  • Olivier, L. & Haumann, F. A. Southern Ocean freshening stalls deep ocean CO2 release in a changing climate. Nat. Clim. Change 15, 1219–1225 (2025).

    Article 
    CAS 

    Google Scholar
     

  • Schmidtko, S., Heywood, K. J., Thompson, A. F. & Aoki, S. Multidecadal warming of Antarctic waters. Science 346, 1227–1231 (2014).

    Article 
    CAS 

    Google Scholar
     

  • Nicholson, S.-A. et al. Storms drive outgassing of CO2 in the subpolar Southern Ocean. Nat. Commun. 13, 158 (2022).

    Article 
    CAS 

    Google Scholar
     

  • Du Plessis, M. et al. The daily-resolved Southern Ocean mixed layer: regional contrasts assessed using glider observations. J. Geophys. Res. Oceans 127, e2021JC017760 (2022).

    Article 

    Google Scholar
     

  • Josey, S. A. et al. Record-low Antarctic sea ice in 2023 increased ocean heat loss and storms. Nature 636, 635–639 (2024).

    Article 
    CAS 

    Google Scholar
     

  • Ferreira, D., Marshall, J., Bitz, C. M., Solomon, S. & Plumb, A. Antarctic Ocean and sea ice response to ozone depletion: a two-time-scale problem. J. Clim. 28, 1206–1226 (2015).

    Article 

    Google Scholar
     

  • Prend, C. J. et al. Ross Gyre variability modulates oceanic heat supply toward the West Antarctic continental shelf. Commun. Earth Environ. 5, 47 (2024).

    Article 

    Google Scholar
     

  • de Jager, W. & Vichi, M. Increased rotational coupling between antarctic sea ice and the atmosphere over the last 30 years. J. Geophys. Res. Oceans 130, e2024JC021239 (2025).

    Article 

    Google Scholar
     

  • Chen, H., Haumann, F. A., Talley, L. D., Johnson, K. S. & Sarmiento, J. L. The deep ocean’s carbon exhaust. Global Biogeochem. Cycles 36, e2021GB007156 (2022).

    Article 
    CAS 

    Google Scholar
     

  • Droste, E. S. et al. Sea ice controls net ocean uptake of carbon dioxide by regulating wintertime stratification. Commun. Earth Environ. 6, 457 (2025).

    Article 

    Google Scholar
     

  • Katlein, C., Hendricks, S. & Key, J. Brief communication: Increasing shortwave absorption over the Arctic Ocean is not balanced by trends in the Antarctic. Cryosphere 11, 2111–2116 (2017).

    Article 

    Google Scholar
     

  • Swart, S. et al. Constraining Southern Ocean air–sea-ice fluxes through enhanced observations. Front. Mar. Sci. 6, 421 (2019).

    Article 

    Google Scholar
     

  • Riihelä, A., Bright, R. M. & Anttila, K. Recent strengthening of snow and ice albedo feedback driven by Antarctic sea-ice loss. Nat. Geosci. 14, 832–836 (2021).

    Article 

    Google Scholar
     

  • Pellichero, V., Sallée, J.-B., Chapman, C. C. & Downes, S. M. The Southern Ocean meridional overturning in the sea-ice sector is driven by freshwater fluxes. Nat. Commun. 9, 1789 (2018).

    Article 

    Google Scholar
     

  • Haumann, F. A., Gruber, N., Münnich, M., Frenger, I. & Kern, S. Sea-ice transport driving Southern Ocean salinity and its recent trends. Nature 537, 89–92 (2016).

    Article 
    CAS 

    Google Scholar
     

  • Arrigo, K. R. Sea Ice as a Habitat for Primary Producers 352–369 (Wiley, 2017).

  • Schofield, O. et al. Antarctic pelagic ecosystems on a warming planet. Trends Ecol. Evol. 39, 1141–1153 (2024).

    Article 

    Google Scholar
     

  • Fretwell, P. T., Boutet, A. & Ratcliffe, N. Record low 2022 Antarctic sea ice led to catastrophic breeding failure of emperor penguins. Commun. Earth Environ. 4, 273 (2023).

    Article 

    Google Scholar
     

  • Spira, T., du Plessis, M. & Swart, S. Processed hydrographic SO data, 2004–2021. Zenodo https://zenodo.org/records/10258138 (2023).

  • de Boyer Montégut, C. Mixed layer depth over the global ocean: an examination of profile data and a profile-based climatology. J. Geophys. Res. 109, C12003 (2004).


    Google Scholar
     

  • Auger, M., Morrow, R., Kestenare, E., Sallée, J.-B. & Cowley, R. Southern Ocean in-situ temperature trends over 25 years emerge from interannual variability. Nat. Commun. 12, 514 (2021).

    Article 
    CAS 

    Google Scholar
     

  • von Kármán, T. Mechanische ähnlichkeit und turbulenz. In Proc. 3rd International Congress of Applied Mechanics 1, 85–93 (1931).


    Google Scholar
     

  • Martinson, D. G. & Wamser, C. Ice drift and momentum exchange in winter antarctic pack ice. J. Geophys. Res. Oceans 95, 1741–1755 (1990).

    Article 

    Google Scholar
     

  • Biddle, L. & Swart, S. The observed seasonal cycle of submesoscale processes in the Antarctic marginal ice zone. J. Geophys. Res. Oceans 125, e2019JC015587 (2020).

    Article 

    Google Scholar
     

  • Hersbach, H. et al. Era5 monthly averaged data on single levels from 1940 to present. Copernicus Climate Change Service (C3S) Climate Data Store (CDS) https://doi.org/10.24381/cds.f17050d7 (accessed 1 September 2024).

  • Grachev, A. A. & Fairall, C. W. Dependence of the Monin–Obukhov stability parameter on the bulk Richardson number over the ocean. J. Appl. Meteorol. Climatol. 36, 406–414 (1997).

    Article 

    Google Scholar
     

  • Thorpe, S. A. The Turbulent Ocean (Cambridge Univ. Press, 2005).

  • Park, Y.-H. et al. Observations of the Antarctic circumpolar current over the Udintsev Fracture Zone, the narrowest choke point in the Southern Ocean. J. Geophys. Res. Oceans 124, 4511–4528 (2019).

    Article 

    Google Scholar
     

  • Dorschel, B. et al. The international bathymetric chart of the Southern Ocean version 2. Sci. Data 9, 275 (2022).

    Article 

    Google Scholar
     

  • Cartopy v0.21.1 (Met Office, 2022); https://scitools.org.uk/cartopy

  • Meier, W., Fetterer, F., Windnagel, A. & Stewart, S. NOAA/NSIDC Climate Data Record of Passive Microwave Sea Ice Concentration, Version 4 (NOAA/NSIDC, 2021); https://nsidc.org/data/g02202/versions/4/

  • Spira, T. Antarctic Winter Water climatology and overturning. GitHub https://github.com/theospira/WW_climatology (2024).

  • Spira, T. Antarctic Winter Water and sea ice variability. GitHub https://github.com/theospira/WW-sea_ice (2025).