Observational evidence indicates enhanced ocean convection near the sea ice edge in the Nordic Sea. However, whether sea ice retreat in a warming climate would further strengthen convection remains uncertain. Using a high-resolution climate model and comparing it with a low-resolution version, we find a more pronounced future increase in convection in the Arctic Ocean. A key reason for this difference is that at higher resolution, resolved boundary currents transport high-density Atlantic water more efficiently toward high latitudes along the ocean boundary. As sea ice retreats and low-density freshwater input diminishes, the high-density water can no longer subduct. Meanwhile, surface currents strengthen more than deeper currents, and the resulting shear weakens stratification before heat loss occurs. Our study suggests that future ocean convection and ventilation in the Arctic Ocean may be stronger than present projections from low-resolution models indicate.