Submarine Ice-Shelf Melt

Warm salty ocean water can circulate beneath ice shelves and melt them from below. Ice shelves float, so this melt does not raise sea level directly, but thinning reduces buttressing and can speed up the flow of grounded ice into the ocean. The IPCC links much of West Antarctica’s observed mass loss since the early 1990s to changes in ice shelves driven by basal melting, and estimates of Antarctic basal meltwater flux are on the order of 1100 to 1600 gigatons per year in recent decades. Antarctica’s grounded ice loss has already raised global mean sea level by about 7.4 ± 1.5 mm since 1992. Our group is developing methods that use time series of high-resolution stereo satellite imagery to map elevation change over floating ice. Repeated stereo DEMs are co-registered and differenced, then combined with estimates of englacial stresses and surface mass balance to isolate basal melt rates.