When I first focused my microscope on the soil sample, I saw organic debris: tiny poppy seeds, insect compound eyes, broken willow twigs, spike moss spores. Dark spheres produced by soil fungi dominated the view.
These are definitely Remains of the Arctic Tundra EcosystemAnd it’s evidence that Greenland’s entire ice sheet disappeared more recently than people realized.
The evidence of past life was found in the most unlikely place: a handful of soil buried under the ice two miles below the peak of the Greenland Ice Sheet. The predictions are clear for the future melting of the ice sheet. At least 90% The ice in Greenland will melt.
(Credit: Schaefer et al., 2016, modified from Nature) Ice sheet model results show how much of Greenland’s ice sheet will remain when the ice is gone from the Camp Century (white dots), GISP2 (red dots), and DYE-3 (black dots) ice sheet coring sites.
In 1993, drillers at the summit completed the Greenland Ice Sheet Project 2 (GISP2) ice core, affectionately known as the “Greenland Ice Sheet Project 2.” 2 Mile Time MachineThe seeds, twigs and spores we found came from a few inches of soil at the bottom of the core – soil that had been left dry and untouched for 30 years in a windowless area. Storage facility in Colorado.
Our new analysis builds on other studies conducted over the past decade. I lost my faith. The Greenland ice sheet has existed continuously since at least the beginning of the Pleistocene glacial period 2.6 million years ago. In 2016, scientists used a model that measured rare isotopes in rocks above and below the GISP2 soil sample to suggest that the ice disappeared at least once. During the past 1.1 million years.
The discovery of these well-preserved tundra ruins confirms that Greenland’s ice sheet previously melted, exposing land below mountain peaks. Soil is formed And there tundra is growing there, which indicates that the ice sheet is vulnerable and may melt again.
The average temperature today at the GISP2 ice drilling camp on the top of the Greenland ice sheet is minus 7 degrees Fahrenheit (minus 22 degrees Celsius). (Credit: Christine Massey, CC BY)
Frozen plant remains suggest that central Greenland was once probably like this dry, rocky tundra photographed in northwest Greenland. (Credit: Paul Bierman/University of Vermont, CC BY-ND)
Landscape with arctic poppies and spikemoss
To the naked eye, these tiny shards of past life are unnoticeable — dark specks floating among the shiny silt and grains of sand. But under a microscope, their story is astonishing: Seeds, megaspores and insect parts combine to paint a picture of a cold, dry, rocky environment that existed for the past million years.
Above ground, Arctic poppies were growing among the rocks, a single cup-shaped flower at the end of each stalk of this small but hardy herbaceous plant, making the most of each day’s light as it followed the sun across the sky.
Seeds (right) found in permafrost two miles beneath the ice are from the Arctic poppy (left). Arterra/Universal Images Group via Getty Images (left), (Credit: Halley Mastro/University of Vermont (right))
Tiny insects buzzed about on the carpets of spikemoss on the tiny rocks, and in summer they crawled across the gravel surface, carrying spores.
(Credit: JF Clovis/Courtesy of the Smithsonian Institution (left); Halley Mastro/Courtesy of University of Vermont (right)) Modern rock spike moss (left) and rock spike moss megaspores (tan spheres, right) from the GISP2 soil sample.
In the rocky soil were black balls called sclerotia, produced by fungi that work with plant roots in the soil to help them get the nutrients they need. Nearby was a willow shrub, adapted to life in the harsh tundra with its small body and bushy hairs covering its stems.
Three tree fragments (right), photographed under a high-powered electron microscope, are Arctic willows — not giant trees, but remnants of the ankle-high shrubs (left) that characterize the Greenland tundra today. (Credit: Peter Prokosch (left), Barry Locke/University of New Hampshire (right))
Each of these organisms left clues in their handfuls of soil: evidence that Greenland’s ice was once replaced by a hardy tundra ecosystem.
Greenland’s ice is fragile
Our discovery will be announced on August 5, 2024. Proceedings of the National Academy of SciencesGreenland’s ice has been shown to be vulnerable to melting if atmospheric carbon dioxide levels are lower than they are today, and concerns about this vulnerability have led scientists to study the ice sheet. 1950s and after.
In the 1960s, a team of engineers extracted the world’s first deep ice core. Camp Century, Nuclear Military Base It was embedded in an ice sheet more than 100 miles off the coast of northwest Greenland. They studied the ice, but the chunks of rock and soil that had risen with the bottom of the core were of little use. They were stored away and lost until they were discovered in 2019. Rediscovered in a lab freezerOur team was among the scientists called in to analyze them.
George Linkletter, of the U.S. Army Corps of Engineers’ Cold Regions Research and Engineering Laboratory, examines ice core fragments in the science trench at Camp Century, which closed in 1966. (Photo courtesy of U.S. Army Photo)
Plant and insect remains were also found in the soil at Camp Century. Frozen under the iceRare isotopes and Illumination Technologywe were able to trace them back to a certain period. About 400,000 years agoThe temperatures then were similar to today.
Well-preserved remains of 400,000-year-old moss (left) and sedge seeds (right) found in a soil core beneath the Greenland ice sheet at Camp Century provide a glimpse into what lived there when the ice disappeared. (Photo by Harry Mastro/University of Vermont)
Another ice core, DYE-3 from South Greenland, Contains DNAThis indicates that during the past million years, that part of the island was covered with spruce forest.
Biological evidence compellingly supports the vulnerability of Greenland’s ice sheet, and the combined findings from the three ice cores mean only one thing: the entire island, except for a few mountainous areas on the east side, must have melted over the past million years.
Disappearance of ice sheets
If Greenland lost its ice, the geography of the world would change, and that would be problematic for humanity.
As the ice sheets melt, sea levels could eventually rise by more than 23 feet. Coastal cities will floodMuch of Miami will be underwater, as will large parts of Boston, New York, Mumbai and Jakarta.
This is what Boston would look like if sea levels rose 16 feet (5 meters). Architecture 2030
Currently, the sea level is More than an inch per decadeIn some places, it will rise several times faster. By 2100, when today’s children are grandparents, sea levels around the world are expected to be several feet higher.
Leveraging the past to understand the future
Rapid ice loss is changing the Arctic, and data on past ecosystems, such as that collected under Greenland’s ice, can help scientists understand how Arctic ecosystems will change as the climate warms.
As temperatures rise, the pure white snow melts and the ice shrinks, exposing dark rocks and soil that absorb the sun’s heat. Becoming more environmentally friendly As the years go by Melting permafrost This then releases more carbon, warming the planet even more.
The authors share their research and images from the ice core drilling. Quincy Massey-Bierman/University of Vermont.
Human-induced climate change is on track to cause temperatures in the Arctic and Greenland to rise beyond those experienced for millions of years. Saving Greenland’s iceResearch shows the world needs to stop emitting greenhouse gases from its energy system Lowering carbon dioxide levels In the atmosphere.
Understanding the environmental conditions that caused the ice sheet’s final loss, and how Greenland’s organisms responded, will be crucial for assessing future risks facing ice sheets and coastal regions around the world.
Paul Bierman is a Gund Institute for Environmental Studies Fellow and Professor of Natural Resources and Environmental Science at the University of Vermont. Harry Mastro is a Gund Institute for Environmental Studies Graduate Fellow and Graduate Research Assistant in Natural Resources and Environmental Science at the University of Vermont. This article is reprinted from conversation Under Creative Commons License.Please read Original article.
