Key points:
- When re-examining sediment from the bottom of a deep ice core extracted from the center of Greenland, researchers found seeds, twigs, and insect parts.
- The composition of the soil suggests that Greenland’s ice melted during a warm period likely within the last million years.
- The study results provide a warning of the sea level rise and damage that could occur with continued climate warming.
For the first time, a new study shows that the center – not just the edges – of Greenland’s ice sheet melted away in the recent geological past. The results, published in Proceedings of the National Academy of Sciences, indicate that the ice-covered island was once home to a green, tundra landscape and that the giant ice sheet is more fragile than originally thought.
Researchers re-examined a few inches of sediment from the bottom of a two-mile deep ice core extracted at the very center of Greenland in 1993. Their examination revealed soil that contained willow wood, insect parts, fungi, and a poppy seed in pristine condition.
In 2016, a separate team of researchers tested rock from the bottom of the same 1993 ice core. Their analysis suggested that the Greenland ice sheet was no more than 1.1 million years old and that there were extended ice-free periods during the Pleistocene epoch.
Now, the results from this study confirm the 2016 “fragile Greenland” hypothesis.
“This new study confirms and extends that a lot of sea-level rise occurred at a time when causes of warming were not especially extreme,” explained reviewer Richard Alley of Penn State.
The team’s findings also suggest that Greenland was warm enough, for long enough, that an entire tundra ecosystem established itself where ice is two miles deep today.
“We now have direct evidence that not only was the ice gone, but that plants and insects were living there,” said study author Paul Bierman, scientist at the University of Vermont. “And that’s unassailable. You don’t have to rely on calculations or models.”
Currently, sea level is rising more than an inch a decade and only getting faster. By the end of the century, sea level is likely to be several feet higher. The fragility of Greenland demonstrated in this study is concerning as the near complete melting of Greenland’s ice over the next centuries to a few millennia would lead to some 23 feet of sea level rise.