UC Irvine

In recent decades, tidewater glaciers in Greenland have exhibited a complex spatial pattern of retreat and contributed significantly to sea level rise. This development has been coincident with the warming of ocean waters around Greenland's continental shelf and within its fjords. Here, I use a combination of regional ocean state estimates, remotely-sensed data of glacier evolution, and novel observations of bathymetry and water temperature from NASA's Ocean Melting Greenland mission to quantify the role of warm, salty Atlantic Water in controlling the retreat of 226 marine-terminating glaciers from 1985 to present. Modeled ocean-induced undercutting of calving margins compared with ice advection and ice front change indicates that glacier perturbations are largely triggered by excess melt by the ocean. Subsequent ice front retreat is determined by the bed geometry underneath the ice and the progression of ice front undercutting after retreat: Shallow protrusions, submerged sills and colder, fresher water act to stabilize ice fronts, while deeper, warmer fjords tend to enhance retreat. Despite the role of the ocean in inducing the inland migration of glacier margins, calving processes still dominate the total ablation on the periphery of the ice sheet. This work highlights the role of ocean temperature variability in modulating the retreat of Greenland's glaciers.