Why Greenland’s Surface Lakes Can Vanish Through Cracks

Takeaway: A Greenland lake can vanish through a crack not just because ice breaks, but because the ice slowly gives way enough to keep the drain open.When a lake sitting on top of the Greenland Ice Sheet suddenly drains, it can send millions of tons of meltwater rushing to the glacier bed, briefly lifting the ice and changing how it slides. This matters far beyond one icy basin: these fast drainage events are one way surface warming can reach deep into an ice sheet, linking summer melt, glacier motion, and future sea-level rise.In this episode, we unpack a new modeling study that asks what really keeps these water-filled cracks moving. The surprising answer is not mainly melting inside the crack. It is the way ice behaves a little like a solid and a little like a very slow fluid. Over minutes to hours, that “give” can keep a fracture open long enough for lake water to keep pouring downward and then spread along the bed.We explain hydraulic fracture without assuming a science background, compare brittle-cracking intuition with the slow sag and creep of real glacier ice, and look at why older elastic-only models struggled to match observed lake-drainage behavior. We also discuss what the model leaves out, including its simplified 2D geometry and limited treatment of subglacial drainage, and why those caveats matter for turning detailed fracture physics into ice-sheet-scale forecasts.Citation: Hageman, T., Mejía, J., Duddu, R., and Martínez-Pañeda, E. (2024). Ice viscosity governs hydraulic fracture that causes rapid drainage of supraglacial lakes. The Cryosphere, 18, 3991–4009. https://doi.org/10.5194/tc-18-3991-2024Disclosure: This Waterlines episode package is designed for production using AI-generated voices.