Ice-Shelf Basal Melt Channels Stabilized by Secondary Flow

Ice-shelf basal channels form due to concentrated submarine melting. They are present in many Antarctic ice shelves and can reduce ice-shelf structural integrity, potentially destabilizing ice shelves by full-depth incision. Here, we describe the viscous ice response to a basal channel-secondary flow-which acts perpendicular to the channel axis and is induced by gradients in ice thickness. We use a full-Stokes ice-flow model to systematically assess the transient evolution of a basal channel in the presence of melting. Secondary flow increases with channel size and reduces the rate of channel incision, such that linear extrapolation or the Shallow-Shelf Approximation cannot project future channel evolution. For thick ice shelves (>600 m) secondary flow potentially stabilizes the channel, but is insufficient to significantly delay breakthrough for thinner ice (<400 m). Using synthetic data, we assess the impact of secondary flow when inferring basal-channel melt rates from satellite observations.