Channelized bottom melting and stability of floating ice shelves

TLDR

The Petermann Glacier ice shelf in northwest Greenland loses about 80 % of its mass to bottom melting before calving into the Arctic Ocean. High‑resolution surveys reveal 1–2 km‑wide, 200–400 m‑deep channels aligned with flow and spaced 5 km, formed by bottom melting, confirmed by melt‑water drilling, and indicating that these deep incisions make the shelf vulnerable to mechanical breakup and climate warming—an overlooked risk.

Abstract

The floating ice shelf in front of Petermann Glacier, in northwest Greenland, experiences massive bottom melting that removes 80% of its ice before calving into the Arctic Ocean. Detailed surveys of the ice shelf reveal the presence of 1–2 km wide, 200–400 m deep, sub‐ice shelf channels, aligned with the flow direction and spaced by 5 km. We attribute their formation to the bottom melting of ice from warm ocean waters underneath. Drilling at the center of one of channel, only 8 m above sea level, confirms the presence of ice‐shelf melt water in the channel. These deep incisions in ice‐shelf thickness imply a vulnerability to mechanical break up and climate warming of ice shelves that has not been considered previously.