The rapid basal melting of ice shelves in the Amundsen Sea drives West Antarctic Ice Sheet mass loss and consequent global sea-level rise. However, ice-shelf basal melting does not increase monotonically under climate change, but instead exhibits pronounced decadal variability. Low-melt periods are linked to weaker circulation in Pine Island Trough, a channel connecting the continental slope to the ice-shelf cavities. Using an ocean–sea ice–ice shelf coupled numerical model, we investigate the circulation changes during the low-melt phase of the 2010s, identifying a west–east asymmetry in trough circulation weakening. The eastern flank experiences enhanced upwelling/downwelling anomalies of warm water that generate a baroclinic flow reinforcing the circulation slowdown and reducing the near-bottom poleward heat flux by ~40% relative to the barotropic component. In contrast, baroclinic anomalies on the western flank oppose the barotropic circulation change, arising from reduced meltwater input. These results demonstrate that spatially heterogeneous baroclinic processes substantially modulate heat transport through the trough and help sustain cooling and low-melt conditions on decadal timescales.

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