Ice cores show Greenland was almost completely ice-free at some point in the last one million years, but the article notes that this ‘happened at lower levels of atmospheric carbon dioxide than present-day levels’. Call it natural variation, but as usual an alarmist can see *potential* trouble anywhere. Here they do at least admit that climate cycles can occur.
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Today, nearly 98% of Greenland is covered in ice — but new research suggests it was virtually ice-free less than a million years ago, says LiveScience.
Over the years, opinion has shifted about whether Greenland has been continuously covered by ice since the start of the Pleistocene epoch, roughly 2.7 million years ago.
But a new fossil discovery, described in a study published Aug. 5 in the journal PNAS, “provides the first direct evidence that the center — not just the edges — of Greenland’s ice sheet melted away in the recent geological past,” according to a statement from the University of Vermont.
“Our new data is the strongest confirmation yet that the ice in the center of the island vanished and was replaced by a tundra ecosystem,” study lead author Paul Bierman, a geologist at the University of Vermont, told Live Science.
To make the discovery, the research team re-examined a sample of an ice core extracted in 1993. They found a plethora of fossils, including willow, fungi and insect body parts. But the most spectacular find was an impeccably preserved Arctic poppy seed.
The team was astonished by the finds. “The original plan with the sample was to measure [carbon-dating] isotopes, we didn’t know we were going to find fossils,” Bierman said.
One key piece of evidence was a specimen of rock spike moss (Selaginella rupestris), which today survives only on sandy and rocky places. “They need the things all plants need to grow, and they can’t get those on top of an ice sheet,” Halley Mastro, a graduate student at the University of Vermont and co-author of the study told Live Science. “They just wouldn’t grow.”
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An ice-free Greenland happened at lower levels of atmospheric carbon dioxide than present-day levels, so there’s potential for Greenland to be ice-free again, which would raise sea levels drastically.
“It will take decades, if not centuries, to lose its ice completely, but most of the sea level rise, more than other places, is coming from Greenland,” Bierman said.
There may be hope, however. “Nature has taken this ice sheet away in the past, and it has come back,” he said.
Full article here.
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Image: Greenland ice core [credit: K. Makinson @ Wikipedia]
via Tallbloke’s Talkshop
August 12, 2024 at 05:23AM
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