Today, almost 98% of Greenland is covered by ice – but new research suggests it was nearly ice-free a million years ago.
Opinion has changed over the years as to whether Greenland has been continuously covered by ice since the beginning of the Pleistocene era, approximately 2.7 million years ago. But a new fossil discovery is described in a study published on August 5 Journal PNAS„Recent geology provides the first direct evidence that the core — not just the edges — of Greenland’s ice sheet melted in the past” Report from the University of Vermont.,
„Our new data is even stronger confirmation that the ice in the center of the island has disappeared and been replaced by a tundra ecosystem,” study lead author Paul Biermann, a geologist at the University of Vermont, told Live Science.
To make the discovery, the research team re-examined a sample of ice extracted in 1993. They found numerous fossils, including willow, fungi and insect body parts. But the most fascinating find was a meticulously preserved arctic poppy seed.
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The team was shocked by these findings. „The original project must scale with the model [carbon-dating] Isotopes, we never knew we were going to find fossils,” Biermann said.
A key piece of evidence is a sample of rock spike moss (Selaginella rubestris)Today it lives only in sandy and rocky places. „All plants need things to grow, and they can’t get them on top of the ice,” University of Vermont graduate student and co-author of the study, Hallie Mastro, told Live Science. „They don’t grow up.”
A 2016 study The center suggests that the current Greenland ice sheet is at most 1.1 million years old. They estimate that the loss of ice at one site, called GISP2, would have left 90% of Greenland ice-free at the time.
Another core was extracted in 1966 off the northwest coast of Greenland Analysis by Bierman and an international team in 2019. They found several fossils – including seeds, twigs and insect body parts – indicating that this part of Greenland was ice-free within the last 500,000 years.
A recent study suggests that central Greenland has also been ice-free for the past 1 million years. According to the report, the landscape, now covered by a 2-mile (3.2-kilometer) thick layer of snow, contains an entire tundra ecosystem, with flowers and small trees.
Revisited by Beerman and Mastro in 1993, the core was housed at the National Science Foundation Ice Core Facility in Colorado and was virtually neglected for more than 30 years.
„The snow part of the embryo has been analyzed in detail,” Beerman said. „The people who were taking the ice cubes didn’t think much about what was underneath. After one set of analyzes of the sediment, it was put in a bag on a shelf. We didn’t know to check if we didn’t. There’s already a plan in the sediments below the ice.”
The discovery that Greenland was once ice-free has implications for the present day.
Ice-free Greenland took place at lower levels of atmospheric carbon dioxide than current levels, so Greenland would become ice-free again, which would drastically raise sea levels.
„It will take decades, if not centuries, to completely lose its ice, but most of the sea-level rise is coming from Greenland, more than anywhere else,” Bierman said.
However there may be hope. „Nature took this ice in the past and it’s back,” he said.
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