Greenland’s Hidden Plumbing: What a Moulin Reveals About Ice, Water, and Sea Level

Takeaway: A Greenland moulin is not just a drainpipe into the ice; its water level can reveal a whole hidden plumbing network working far below the surface.Greenland’s summer meltwater does not simply run off the ice sheet like rain down a sidewalk. Some of it pours into deep blue shafts called moulins, reaches the bed hundreds of meters below, and helps set the water pressure that can speed up or slow down the ice itself. In this episode, we follow one small moulin in western Greenland and ask a deceptively simple question: why didn’t its water level bounce up and down as much as the researchers’ first models said it should? The answer points to a hidden network of channels beneath the ice, where water from many places may be smoothing out the daily pulse of melt. That matters because these unseen drainage systems help shape how Greenland responds to warmer summers and how much ice eventually reaches the ocean. Featured paper: Trunz, C., Poinar, K., Andrews, L. C., Covington, M. D., Mejia, J., Gulley, J., and Siegel, V.: Observed and modeled moulin heads in the Pâkitsoq region of Greenland suggest subglacial channel network effects, The Cryosphere, 17, 5075–5094, 2023, https://doi.org/10.5194/tc-17-5075-2023. This Waterlines episode uses AI-generated voices for the host conversation.