Limits to future expansion of surface-melt-enhanced ice flow into the interior of western Greenland

  • Limits to surface-melt-enhanced ice flow
  • Kristin Poinar, Ian Joughin, Sarah B. Das, Mark D. Behn, Jan T. M. Lenaerts, Michiel R. van den Broeke
  • Geophysical Research Letters, March 2015, American Geophysical Union (AGU)
  • DOI: 10.1002/2015gl063192

Lakes on top of the Greenland Ice Sheet

What is it about?

Each summer, meltwater on top of the Greenland Ice Sheet pools into small lakes. Many lakes eventually fracture through the ice, delivering their water to the base of the ice sheet, where it can speed ice flow. We show that even though the locations of these lakes are changing as the climate warms, the points where their water is ultimately injected to the ice-sheet base are likely to remain stationary.

Why is it important?

If water reaches dry parts of the ice-sheet base, it could lubricate these areas and significantly speed ice flow, raising global sea levels. However, we show that water is unlikely to reach dry areas, even in future warm climates when meltwater will form on the ice-sheet surface directly above these areas. Our work does NOT show that the Greenland Ice Sheet is safe from climate change. It only suggests that lakes on its surface are unlikely to be the death of the ice sheet. The ice sheet continues to shrink year on year, and we continue to study the processes that are shrinking it so that we may accurately predict and plan for future higher sea levels.


Kristin Poinar
NASA Goddard Space Flight Center

This work stitches together many pieces of evidence that point to its conclusion. Taken individually, no argument is watertight. But combining melt rates, satellite images from a few different sensors, ice-sheet model results, and data on ice motion... all these things together told a convincing story that needed to be written up. Read more at SciWorthy:

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The following have contributed to this page: Kristin Poinar