Fracture propagation to the base of the Greenland ice sheet during supraglacial lake drainage

• Published in: Science
• Main Authors: Das, SB, Joughin, I, Behn, MD, Howat, IM, King, MA, Lizarralde, D, Bhatia, MP
• Format: Article in Journal/Newspaper
• Language: English
• Published: Amer Assoc Advancement Science 2008
• Subjects: Earth Sciences; Physical Geography and Environmental Geoscience; Physical Geography and Environmental Geoscience not elsewhere classified; Greenland; Ice Sheet
• Online Access: https://doi.org/10.1126/science.1153360; http://ecite.utas.edu.au/81951

Surface meltwater that reaches the base of an ice sheet creates a mechanism for the rapid response of ice flow to climate change. The process whereby such a pathway is created through thick, cold ice has not, however, been previously observed. We describe the rapid (<2 hours) drainage of a large supraglacial lake down 980 meters through to the bed of the Greenland Ice Sheet initiated by water-driven fracture propagation evolving into moulin flow. Drainage coincided with increased seismicity, transient acceleration, ice-sheet uplift, and horizontal displacement. Subsidence and deceleration occurred over the subsequent 24 hours. The short-lived dynamic response suggests that an efficient drainage system dispersed the meltwater subglacially. The integrated effect of multiple lake drainages could explain the observed net regional summer ice speedup.