The full length of Parker Ice Tongue on the Victoria Land Coast, Antarctica, calved in March 2020. Calving of this magnitude (18 km) is not previously seen for this location. The mean growth rate (189 m yr-1) indicates that it is now at a historic minimum for at least the last 165 years. The 2020 calving occurred during a complete breakout of the land-fast sea ice. Here we link seasonal changes in ice velocity to the land-fast sea ice extent. With Summer/winter increase/decrease in velocity correlates with decrease/increase in land-fast sea ice extent (-0.62 with R-squared of -0.39). Although Parker Ice Tongue was relatively small compared to other ice tongues in the region, its sensitive behaviour highlights the vulnerability of ice tongues to a changing ocean environment, and poses questions about the future stability of larger floating ice masses if land-fast sea ice extent decreases more broadly in the future.