(Press-News.org) Contact information: Charlotte Hsu
chsu22@buffalo.edu
716-645-4655
University at Buffalo
Greenland's shrunken ice sheet: We've been here before
Clues in the Arctic fossil record suggest that 3-5,000 years ago, the ice sheet was the smallest it has been in the past 10,000 years
BUFFALO, N.Y. — Think Greenland's ice sheet is small today?
It was smaller — as small as it has ever been in recent history — from 3-5,000 years ago, according to scientists who studied the ice sheet's history using a new technique they developed for interpreting the Arctic fossil record.
"What's really interesting about this is that on land, the atmosphere was warmest between 9,000 and 5,000 years ago, maybe as late as 4,000 years ago. The oceans, on the other hand, were warmest between 5-3,000 years ago," said Jason Briner, PhD, University at Buffalo associate professor of geology, who led the study.
"What it tells us is that the ice sheets might really respond to ocean temperatures," he said. "It's a clue to what might happen in the future as the Earth continues to warm."
PHOTOS: http://www.buffalo.edu/news/releases/2013/11/033.html
The findings appeared online on Nov. 22 in the journal Geology. Briner's team included Darrell Kaufman, an organic geochemist from Northern Arizona University; Ole Bennike, a clam taxonomist from the Geological Survey of Denmark and Greenland; and Matthew Kosnik, a statistician from Australia's Macquarie University.
The study is important not only for illuminating the history of Greenland's ice sheet, but for providing geologists with an important new tool: A method of using Arctic fossils to deduce when glaciers were smaller than they are today.
Scientists have many techniques for figuring out when ice sheets were larger, but few for the opposite scenario.
"Traditional approaches have a difficult time identifying when ice sheets were smaller," Briner said. "The outcome of our work is that we now have a tool that allows us to see how the ice sheet responded to past times that were as warm or warmer than present — times analogous to today and the near future."
The technique the scientists developed involves dating fossils in piles of debris found at the edge of glaciers.
To elaborate: Growing ice sheets are like bulldozers, pushing rocks, boulders and other detritus into heaps of rubble called moraines.
Because glaciers only do this plowing when they're getting bigger, logic dictates that rocks or fossils found in a moraine must have been scooped up at a time when the associated glacier was older and smaller.
So if a moraine contains fossils from 3,000 years ago, that means the glacier was growing — and smaller than it is today — 3,000 years ago.
This is exactly what the scientists saw in Greenland: They looked at 250 ancient clams from moraines in three western regions, and discovered that most of the fossils were between 3-5,000 years old.
The finding suggests that this was the period when the ice sheet's western extent was at its smallest in recent history, Briner said.
"Because we see the most shells dating to the 5-3000-year period, we think that this is when the most land was ice-free, when large layers of mud and fossils were allowed to accumulate before the glacier came and bulldozed them up," he said.
Because radiocarbon dating is expensive, Briner and his colleagues found another way to trace the age of their fossils.
Their solution was to look at the structure of amino acids — the building blocks of proteins — in the fossils of ancient clams. Amino acids come in two orientations that are mirror images of each other, known as D and L, and living organisms generally keep their amino acids in an L configuration.
When organisms die, however, the amino acids begin to flip. In dead clams, for example, D forms of aspartic acid start turning to L's.
Because this shift takes place slowly over time, the ratio of D's to L's in a fossil is a giveaway of its age.
Knowing this, Briner's research team matched D and L ratios in 20 Arctic clamshells to their radiocarbon-dated ages to generate a scale showing which ratios corresponded with which ages. The researchers then looked at the D and L ratios of aspartic acid in the 250 Greenland clamshells to come up with the fossils' ages.
Amino acid dating is not new, but applying it to the study of glaciers could help scientists better understand the history of ice — and climate change — on Earth.
INFORMATION:
The study was funded by the National Geographic Society and U.S. National Science Foundation.
Greenland's shrunken ice sheet: We've been here before
Clues in the Arctic fossil record suggest that 3-5,000 years ago, the ice sheet was the smallest it has been in the past 10,000 years
2013-11-23
ELSE PRESS RELEASES FROM THIS DATE:
'Wise chisels': Art, craftsmanship, and power tools
2013-11-23
'Wise chisels': Art, craftsmanship, and power tools
CAMBRIDGE, MA -- It's often easy to tell at a glance the difference between a mass-produced object and one that has been handcrafted: The handmade item is likely to have distinctive imperfections and ...
NASA's solar observing fleet to watch Comet ISON's journey around the sun
2013-11-23
NASA's solar observing fleet to watch Comet ISON's journey around the sun
It began in the Oort cloud, almost a light year away. It has traveled for over a million years. It has almost reached the star that has pulled it steadily forward for so ...
Study finds link between allergies and increased risk of blood cancers in women
2013-11-23
Study finds link between allergies and increased risk of blood cancers in women
Gender may play a role in the association of chronic immune stimulation and development of hematologic cancers
SEATTLE – A team of scientists looking into the interplay ...
Paths not taken: Notch signaling pathway keeps immature T cells on the right track
2013-11-23
Paths not taken: Notch signaling pathway keeps immature T cells on the right track
Implications for fighting T-cell leukemias
PHILADELPHIA - The lab of Avinash Bhandoola, PhD, professor of Pathology and Laboratory Medicine, has studied ...
Stuck on flu
2013-11-23
Stuck on flu
How a sugar-rich mucus barrier traps the virus -- and it gets free to infect
Researchers at the University of California, San Diego School of Medicine have shown for the first time how influenza A viruses snip through a protective mucus net ...
Evidence of jet of high-energy particles from Milky Way's black hole found by astronomers
2013-11-23
Evidence of jet of high-energy particles from Milky Way's black hole found by astronomers
For decades, astronomers have sought strong evidence that the supermassive black hole at the center of our Milky Way galaxy is producing a jet of ...
UCLA, Emory researchers find a chemical signature for 'fast' form of Parkinson's
2013-11-22
UCLA, Emory researchers find a chemical signature for 'fast' form of Parkinson's
Earlier detection may provide more effective disease management
The physical decline experienced by Parkinson's disease patients eventually leads to disability and ...
Pre-industrial rise in greenhouse gases had natural and anthropogenic causes
2013-11-22
Pre-industrial rise in greenhouse gases had natural and anthropogenic causes
CORVALLIS, Ore. – For years scientists have intensely argued over whether increases of potent methane gas concentrations in the atmosphere – from about 5,000 years ago to the start ...
Preschoolers exposure to television can stall their cognitive development
2013-11-22
Preschoolers exposure to television can stall their cognitive development
Children with TVs in the bedroom linked to weak understanding of mental states
Washington, DC (November 19, 2013) – Television is a powerful agent of development for children, ...
Patients with diabetes who use mail order pharmacy are less likely to visit ERs
2013-11-22
Patients with diabetes who use mail order pharmacy are less likely to visit ERs
OAKLAND, Calif. — Patients with diabetes who received prescribed heart medications by mail were less likely to visit the emergency room than those patients who picked up prescriptions ...
LAST 30 PRESS RELEASES:
AI algorithm based on routine mammogram + age can predict women’s major cardiovascular disease risk
New hurdle seen to prostate screening: primary-care docs
MSU researchers explore how virtual sports aid mental health
Working together, cells extend their senses
Cheese fungi help unlock secrets of evolution
Researchers find brain region that fuels compulsive drinking
Mental health effects of exposure to firearm violence persist long after direct exposure
Research identifies immune response that controls Oropouche infection and prevents neurological damage
University of Cincinnati, Kent State University awarded $3M by NSF to share research resources
Ancient DNA reveals deeply complex Mastodon family and repeated migrations driven by climate change
Measuring the quantum W state
Researchers find a way to use antibodies to direct T cells to kill Cytomegalovirus-infected cells
Engineers create mini microscope for real-time brain imaging
Funding for training and research in biological complexity
The Journal of Nuclear Medicine Ahead-of-Print Tip Sheet: September 12, 2025
ISSCR statement on the scientific and therapeutic value of human fetal tissue research
Novel PET tracer detects synaptic changes in spinal cord and brain after spinal cord injury
Wiley advances Knowitall Solutions with new trendfinder application for user-friendly chemometric analysis and additional enhancements to analytical workflows
Benchmark study tracks trends in dog behavior
OpenAI, DeepSeek, and Google vary widely in identifying hate speech
Research spotlight: Study identifies a surprising new treatment target for chronic limb threatening ischemia
Childhood loneliness and cognitive decline and dementia risk in middle-aged and older adults
Parental diseases of despair and suicidal events in their children
Acupuncture for chronic low back pain in older adults
Acupuncture treatment improves disabling effects of chronic low back pain in older adults
How interstellar objects similar to 3I/ATLAS could jump-start planet formation around infant stars
Rented e-bicycles more dangerous than e-scooters in cities
Ditches as waterways: Managing ‘ditch-scapes’ to strengthen communities and the environment
In-situ molecular passivation enables pure-blue perovskite LEDs via vacuum thermal evaporation
Microscopes can now watch materials go quantum with liquid helium
[Press-News.org] Greenland's shrunken ice sheet: We've been here beforeClues in the Arctic fossil record suggest that 3-5,000 years ago, the ice sheet was the smallest it has been in the past 10,000 years