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Surface winds around the Antarctic continent control coupled ocean‐ice processes that influence the climate system, including bottom water production, heat transport onto the continental shelf and sea ice coverage. However, few studies have examined projected changes in these winds, even though it would aid in the interpretation and understanding of the ocean's response to climate change. Using Coupled Model Intercomparison Project Phase 6 and reanalysis data, we show a significant reduction in the near‐Antarctic surface winds throughout the historical period that continues until the end of the twenty‐first century, amounting to 23% and 7% for the easterly and southerly wind components respectively under the high emission scenario. The most intense weakening happens during the summer season. We find that the weakening is coherent with the trend toward a positive Southern Annular Mode and a reduction of the pole‐to‐coast meridional pressure gradient, which we term Antarctic Annular Index. Plain Language Summary: Surface winds over the ocean around the Antarctic continent influence several aspects of the oceanic circulation and sea ice in the region that become relevant in the context of climate change. For example, Antarctic coastal surface winds have been found to drive the warming experienced in some regions that subsequently triggers increased ice shelf melt. However, there is little understanding regarding how this wind regime is expected to change in the future, with most research focusing on the mid‐latitude westerlies. In this work, we use Coupled Model Intercomparison Project Phase 6 models to quantify projected changes in these winds to the end of the twenty‐first century, hoping that it will aid in the interpretation of the ocean's response to climate change. Under the high emission scenario, we find a significant weakening of 23% for the easterly wind component and 7% for the meridional wind component. This weakening can be partly explained by a large‐scale pattern of change in sea level pressure that reflects in an increase of the atmospheric mode of variability known as the Southern Annular Mode, and a decrease of the pole‐to‐coast surface pressure gradient, which we term Antarctic Annular Index. Key Points: Coupled Model Intercomparison Project Phase 6 models show a weakening of the near‐Antarctic surface winds during the period 1979–2015Future projections in CMIP6 models show that the weakening trend continues until the end of the twenty‐first centuryWeakened winds are associated with a more positive Southern Annular Mode and a reduction in the pole‐to‐coast meridional pressure gradient [ABSTRACT FROM AUTHOR]

The Southern Ocean has undergone significant climate-related changes over recent decades, including intensified westerly winds and increased radiative heating. The interplay between wind-driven cooling and radiative warming of the ocean is complex and remains unresolved. In this study, idealized wind and thermal perturbations are analyzed in a global ocean–sea ice model at two horizontal resolutions: nominally, 1° and 0.1°. The sea surface temperature (SST) response shows a clear transition from a wind-driven cooling phase to a warming phase. This warming transition is largely attributed to meridional and vertical Ekman heat advection, which are both sensitive to model resolution due to the model-dependent components of temperature gradients. At higher model resolution, due to a more accurate representation of near-surface vertical temperature inversion and upward Ekman heat advection around Antarctica, the anomalous SST warming is stronger and develops earlier. The mixed layer depth at midlatitudes initially increases due to a wind-driven increase in Ekman transport of cold dense surface water northward, but then decreases when the thermal forcing drives enhanced surface stratification; both responses are more sensitive at lower model resolution. With the wind intensification, the residual overturning circulation increases less in the 0.1° case because of the adequately resolved eddy compensation. Ocean heat subduction penetrates along more tilted isopycnals in the 1° case, but it orients to follow isopycnal layers in the 0.1° case. These findings have implications for understanding the ocean response to the combined effects of Southern Hemisphere westerly wind changes and anthropogenic warming. [ABSTRACT FROM AUTHOR]