Sensitivity of Heinrich-type ice-sheet surge characteristics to boundary forcing perturbations

Abstract. Heinrich-type ice-sheet surges are one of the prominent signals glacial climate variability. They characterised as abrupt, quasi-periodic episodes instabilities during which large numbers icebergs released from Laurentide ice sheet. The mechanisms controlling timing and occurrence remain poorly constrained to this day. Here, we use a coupled sheet–solid Earth model identify quantify importance boundary forcing for surge cycle length two streams sheet – land-terminating Mackenzie stream marine-terminating Hudson stream. Both show responses similar magnitude surface mass balance geothermal heat flux perturbations, but is more sensitive temperature fact likely caused by warmer in region. Ocean sea-level well different frequencies same have negligible effect on length. simulations also highlight that only certain parameter space exists under oscillations can be maintained. Transitioning an oscillatory state persistent streaming result volume loss up 30 % respective drainage basin otherwise constant conditions. We susceptible undergoing such transition response all tested positive perturbations. This underlines potential region contributed abrupt change events last deglaciation.