A large crack seen in Petermann Glacier. Photo: NASA/Nathan Kurtz

A rare, long-term record of Greenland ice melt reveals the world's largest island shed ice nearly 6 times faster in the past decade when compared to the 1980s, an increase that is already contributing to sea level rise and altered ocean currents, a new study finds.

Why it matters: Greenland's fate will help determine the future viability of coastal megacities around the world, from New York to Shanghai, as sea levels rise in response to added freshwater.

What they did: For the study, published in Proceedings of the National Academy of Sciences, researchers compared data on the discharge of glacial ice into the ocean from 260 glaciers with the accumulation of snow in the interior of the island, as gathered from regional climate models.

What they found: The acceleration of Greenland's melt, which is happening due to warming air and ocean temperatures, has contributed nearly 14 millimeters in global sea level rise since 1972.

  • Half of this increase has occurred in just the past 8 years.
  • The Greenland Ice Sheet shed mass every year since 1998, even when the summer was relatively cool and inland snowfall was above average.
  • Relatively cool summers can slow surface melt, but don't stop fast-moving glaciers from flowing into the sea.
  • The regions contributing the most to ice loss so far are Northwest and Southeastern Greenland.
  • Study co-author Eric Rignot warns future ice loss could come from northern Greenland, which is seeing rapid changes. "We have time to prepare and re-adjust, but time is running out to avoid massive problems near the end of the century," he tells Axios.

What they're saying: Richard Alley, a glacier expert at Penn State University who was not involved in the new study, says the research is especially useful for laying out year-to-year variability in snowfall and mass loss.

"The big picture, from this work and much earlier work, remains clear: with warming, the increase in mass loss from surface melting has exceeded the increase in snowfall, causing net mass loss."
— Richard Alley, Penn State University

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