When we first focused our microscope on the soil sample, bits of organic matter came into view: tiny poppy seeds, insect eyes, broken willow branches, spike moss spores. Dark spheres made by soil fungi dominated the view.
These are obviously Remnants of the Arctic Tundra Ecosystem– And evidence that Greenland’s entire ice sheet disappeared more recently than people thought.
This small hint of past life came from the most unexpected place: a small amount of soil buried under ice two miles below the top of the Greenland ice sheet. The predictions for the future melting of the ice sheet are not vague. When the ice disappears from the top, At least 90% The ice in Greenland would have melted.
(Source: Adapted from Schaefer et al., 2016, Nature) Glacier model results show how much of the Greenland Ice Sheet remains after ice loss at the Camp Century (white dots), GISP2 (red dots), and DYE-3 (black dots) ice coring sites.
In 1993, top drillers completed an ice core nicknamed GISP2 (Greenland Ice Sheet Project 2). 2 mile time machine. The seeds, twigs and spores we found came from a few inches of soil at the bottom of the core, which had been buried in a dry, windowless location for 30 years and had not been touched. Colorado Storage Facility.
Our new analysis builds on the work of others over the past decade. Faith is split Greenland’s ice sheet has existed continuously since at least 2.6 million years ago, when the Pleistocene glaciation began. In 2016, scientists who measured rare isotopes in rocks above and below the GISP2 soil samples used models to suggest that the ice disappeared at least once. Over the past 1.1 million years.
Now, by discovering well-preserved tundra remains, we have confirmation that Greenland’s glaciers did indeed melt long ago, exposing the ground beneath their summits for a long time. For the soil to form And the fact that tundra can grow there tells us that the glaciers are fragile and can melt again.
The average temperature today at the GISP2 ice mining camp on the top of the Greenland Ice Sheet is minus 7 degrees Fahrenheit (minus 22 degrees Celsius). (Source: Christine Massey, CC BY)
Frozen plant remains suggest central Greenland probably once looked like this dry, rocky tundra. This image was taken in northwest Greenland. (Source: Paul Bierman/University of Vermont, CC BY-ND)
Landscape with Arctic poppies and moss
To the naked eye, these tiny fragments of past life are unremarkable—dark specks floating among the glittering silt and sand particles. But when viewed under a microscope, the stories they tell are astonishing. The seeds, macrospores, and bits of insects come together to paint a picture of the cold, dry, rocky environment that existed for the past million years.
Above ground, Arctic poppies grew among the rocks. On each stem of this small but tenacious herb, a single cup-shaped flower followed the sun across the sky, making the most of each day’s light.
Right, the seeds found in frozen soil recovered from two miles under 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 buzz and flutter over the clumps of rock moss, and in summer they crawl across the gravel surface, bearing spores.
(Credit: JF Clovis/Smithsonian Institution (left), Halley Mastro/University of Vermont (right)) Modern rock moss (left) and rock moss macrospores (brown spheres, right) from GISP2 soil samples.
The rocky soil contained dark spheres called sclerotia, produced by fungi that worked with the roots of plants in the soil to help them obtain the nutrients they needed. Nearby, willow shrubs were small in size and had hairy stems, adapting to life in the harsh tundra.
Three pieces of wood (right) seen under a high-power electron microscope were Arctic willows. They were not from giant trees, but rather the remains of ankle-high shrubs (left) that characterize the Greenland tundra today. (Credit: Peter Prokosch; (left), Barry Rock/University of New Hampshire (right))
All of this life left behind clues in a handful of dirt, evidence that suggests Greenland’s ice was once replaced by a robust tundra ecosystem.
Greenland’s ice is fragile
Our findings published on August 5, 2024 Proceedings of the National Academy of Sciences of the United States of AmericaGreenland’s ice sheet is more vulnerable to melting under lower atmospheric carbon dioxide concentrations than today, and concerns about this vulnerability have led scientists to study the ice sheet. Since the 1950s.
In the 1960s, a team of engineers extracted the world’s first deep ice core. Camp Centuryah Nuclear military base It was embedded in an ice sheet 100 miles off the northwest coast of Greenland. They studied the ice, but the rock and dirt chunks that came up with the core bottom were of little use. They were stored until 2019, when they were lost. Rediscovered in a lab freezerOur team was among the scientists dispatched to analyze this.
George Linkletter, working for the U.S. Army Corps of Engineers Cold Regions Research and Engineering Laboratory, examines an ice core fragment in the scientific trench at Camp Century. The site was closed in 1966. (Source: US Army Photograph)
In the Camp Century soil we also found remains of plants and insects. freeze under the ice. Using rare isotopes luminescent technologyWe were able to estimate the era in which they dated. About 400,000 years agoWhen the temperature was similar to today.
The exquisitely preserved remains of a 400,000-year-old moss on the left and a sedge seed on the right were found in a soil core beneath the Greenland ice sheet at Camp Century and tell the story of what lived there when the ice disappeared. (Credit: Halley Mastro/University of Vermont)
Another ice core from southern Greenland, DYE-3 Contains DNAThis shows that at some point in the last million years, that part of the island was covered with spruce forest.
Biological evidence makes a compelling argument for the vulnerability of the Greenland ice sheet. The results from all three ice cores combined suggest only one thing: the entire island has lost ice over the past million years, except for a few mountainous areas in the east.
Lose a glacier
If Greenland’s ice disappears, the world’s landscape will change, and this will pose huge challenges to humanity.
As the glaciers melt, sea levels will eventually rise by more than 23 feet. Coastal cities will be flooded. Most of Miami will be underwater, as will large parts of Boston, New York, Mumbai and Jakarta.
This is what happens in Boston when sea levels rise by 16 feet (5 meters). Architecture 2030
Sea levels are rising today More than 1 inch every 10 yearsAnd in some places, it’s happening several times faster: By 2100, when today’s children become grandparents, global sea levels are likely to rise several feet more.
Using the past to understand the future
Rapid ice loss is changing the Arctic. Data on past ecosystems, such as those collected from beneath Greenland’s ice, are helping scientists understand how the Arctic’s ecology will change as the climate warms.
As temperatures rise, the bright white snow melts and the ice shrinks, revealing dark rock and soil that absorb heat from the sun. The Arctic Become greener As each year passes, Sea ice beneath the permafrost And it releases more carbon, which makes the planet warmer.
The author shares research and images from ice core drilling. Quincy Massey-Beerman/University of Vermont.
Human-caused climate change is causing the Arctic and Greenland to warm more than they have in millions of years. To save Greenland’s iceStudies show the world needs to stop greenhouse gas emissions from its energy system. lower carbon dioxide levels In the air.
Finally, understanding the environmental conditions that led to the ice loss and how life in Greenland responded will be critical to assessing future risks to glaciers and coastal communities around the world.
Paul Bierman is a Fellow at the Gund Institute for the Environment and a Professor of Natural Resources and Environmental Sciences at the University of Vermont. Halley Mastro is a Graduate Fellow at the Gund Institute for the Environment and a Research Assistant in the Graduate School of Natural Resources and Environmental Sciences at the University of Vermont. This article was republished from conversation ~Below Creative Commons License. Read it Original article.
