Effect of orbital‐scale climate cycling and meltwater drainage on ice sheet grounding line migration

Abstract

Ice shelf response to climate cycling introduces hysteretic behavior in outlet glaciers, with the evolution of meltwater drainage networks enhancing this effect. The 2002 collapse of the Larsen B ice shelf (one of the floating extensions formed from glaciers flowing off the Antarctic Peninsula into the Weddell Sea) followed the development of widespread, poorly drained surface melt ponds during the atypical warmth of the 2001–2002 summer melt season. Yet, for at least the past half century, the floating termini of outlet glaciers in Greenland did not collapse despite being exposed to summer mean temperatures and melt rates that far exceed those recorded in 2001–2002 on the Antarctic Peninsula. We suggest that this paradox can be explained by the advection of well‐developed englacial drainage networks within Greenland's extensive ablation zone. The efficiency of this plumbing system limits meltwater ponding within crevasses and the subsequent ice shelf failure observed on the Antarctic Peninsula. Whether progressive or abrupt, ice shelf removal leads to near‐synchronous glacier retreat. Conversely, glaciation of fjords is delayed during ice shelf formation. Ultimately, the relatively rapid loss and gradual establishment of ice shelf buttressing amid climate cycling leads to an asymmetric response in outlet glacier dynamics. This asymmetry may have implications for the future of existing and recently calved ice shelves, eustatic sea level, and the hysteretic behavior of ice sheets.