Surface‐melt driven Laurentide Ice Sheet retreat during the early Holocene

Abstract

To better understand mechanisms of ice‐sheet decay, we investigate the surface mass balance of the Laurentide Ice Sheet (LIS) during the early Holocene, a period of known rapid LIS retreat. We use a surface energy‐mass balance model (EMBM) driven with conditions derived from an equilibrium atmosphere‐ocean general circulation model 9 kilo‐years ago simulation. Our EMBM indicates a net LIS surface mass balance of −0.67 ± 0.13 m yr−1, with losses primarily due to enhanced boreal summer insolation and warmer summers. This rate of loss compared to LIS volume reconstructions suggests that surface ablation accounted for 74 ± 22% of the LIS mass loss with the remaining loss likely driven by dynamics resulting in basal sliding and calving. Thus surface melting likely played a governing role in the retreat and disappearance of this ice sheet.