Cryosphere 7, 1565–1577 (2013)

Credit: © ISTOCK/THINKSTOCK

With the warming climate, most glaciers and ice caps are retreating. However, a lack of observations, spatially and temporally, makes it difficult to draw global conclusions. Accumulation-area ratio (AAR) is a technique for projecting changes in global glacier volume. If a glacier is in balance with the climate — that is, not experiencing retreat or advance — it has an AAR value equal to the equilibrium value of AAR0. Glaciers with values less than AAR0 will retreat at lower altitudes until they reach equilibrium.

Sebastian Mernild, of Los Alamos National Laboratory, USA, and co-workers build on AAR assessments to address the global undersampling and to estimate committed ice losses due to the current climate. Using the available observations for 1971–2010, they find glaciers are further from equilibrium than previous work reported. Committed losses of 32±12% by area and 38±16% by volume are estimated if the climate remains as it is at present. The large uncertainties associated with these values could be reduced by more observations from undersampled regions.