Ice sheet mass flow and balance with constituent terms 2010–19

Ice sheet mass loss is typically provided for grounded ice, because changes in floating ice are more difficult to measure and contribute minimally to sea level rise. However, gross freshwater mass flow rate across ice sheet boundaries, including floating ice, is a better metric of ice sheet health. Here, we present total mass flows across ice sheet boundaries for both the Greenlandic and Antarctic ice sheets and their peripheral glaciers from 2010 through 2019. In addition to total mass flow, we provide constituent terms and gross rather than net values, including components that combine to provide surface mass balance. Ice mass loss in Greenland is 330 50 Gt yr-1 which is 30% larger than the 255 40 Gt yr-1 grounded ice mass loss estimates that neglect floating ice changes. Ice mass loss in Antarctica is 450 270 Gt yr-1 which is 2.4x the 190 115 Gt yr-1 grounded ice mass loss estimates. Freshwater mass flow rate from Greenland is 1065 120 Gt yr-1 or 3x mass loss (4x grounded mass loss), and from Antarctica is 3110 1515 Gt yr-1, or 7x mass loss (16x grounded mass loss).