Totten Ice Shelf history over the past century interpreted from satellite imagery

Abstract. Totten Glacier is currently the largest source of mass loss in the East Antarctic Ice Sheet and it is projected to be a large source of sea-level rise over the coming century. The glacier has been losing mass for decades and inland thinning was detected in the earliest satellite-altimetry observations in the early 1990s, but when the glacier first started losing mass remains unknown. We calculate decadal ice-speed anomalies to confirm that Totten Glacier has not undergone sustained acceleration since at least 1973. Together with observations of grounding-line retreat from 1973–1989, we confirm that the glacier was already out of balance in the 1970s. Surface undulations form on the Totten Ice Shelf adjacent to an ice rumple near the grounding line in response to time-varying melt rates and are preserved downstream for several decades. From utilizing the full suite of Landsat imagery, we produce a century-long record of surface-undulation formation that we interpret as a qualitative record of basal-melt-rate variability. An anomalous ~20-year absence of undulations associated with the mid-20^th century manifests a period when ice passing over the ice rumple was pervasively thinner, and may represent an anonymously warm period that triggered the onset of modern-day mass loss at Totten Glacier. Our results highlight that the currently available ~30-year satellite altimetry records are not long enough to capture the full scale of decadal variability in basal-melt rates and mass-loss patterns.