Biases in ice sheet models from missing noise-induced drift

Abstract

Abstract. Most climatic and glaciological processes exhibit internal variability, which is omitted from many ice sheet model simulations. Prior studies have found that climatic variability can change ice sheet mean state. We show in this study that variability in frontal ablation of marine-terminating glaciers changes the mean state of the Greenland Ice Sheet through noise-induced drift. Idealized simulations and theory show that noise-induced bifurcations and nonlinearities in variable ice sheet processes are likely the cause of the noise-induced drift in marine ice sheet dynamics. The lack of such noise-induced drift in spinup and transient ice sheet simulations is a potentially omnipresent source of bias in ice sheet models.