(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:
Intra-arterial tenecteplase for acute stroke after successful endovascular therapy
Study reveals beneficial microbes that can sustain yields in unfertilized fields
Robotic probe quickly measures key properties of new materials
Climate change cuts milk production, even when farmers cool their cows
Frozen, but not sealed: Arctic Ocean remained open to life during ice ages
Some like it cold: Cryorhodopsins
Demystifying gut bacteria with AI
Human wellbeing on a finite planet towards 2100: new study shows humanity at a crossroads
Unlocking the hidden biodiversity of Europe’s villages
Planned hydrogen refuelling stations may lead to millions of euros in yearly losses
Planned C-sections increase the risk of certain childhood cancers
Adults who have survived childhood cancer are at increased risk of severe COVID-19
Drones reveal extreme coral mortality after bleaching
New genetic finding uncovers hidden cause of arsenic resistance in acute promyelocytic leukemia
Native habitats hold the key to the much-loved smashed avocado’s future
Using lightning to make ammonia out of thin air
Machine learning potential-driven insights into pH-dependent CO₂ reduction
Physician associates provide safe care for diagnosed patients when directly supervised by a doctor
How game-play with robots can bring out their human side
Asthma: patient expectations influence the course of the disease
UNM physician tests drug that causes nerve tissue to emit light, enabling faster, safer surgery
New study identifies EMP1 as a key driver of pancreatic cancer progression and poor prognosis
XPR1 identified as a key regulator of ovarian cancer growth through autophagy and immune evasion
Flexible, eco-friendly electronic plastic for wearable tech, sensors
Can the Large Hadron Collider snap string theory?
Stuckeman professor’s new book explores ‘socially sustainable’ architecture
Synthetic DNA nanoparticles for gene therapy
New model to find treatments for an aggressive blood cancer
Special issue of Journal of Intensive Medicine analyzes non-invasive respiratory support
T cells take aim at Chikungunya virus
[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