Dating of Greenland ice cores by flow models, isotopes, volcanic debris, and continental dust
When archaeologists want to learn about the history of an ancient civilization, they dig deeply into the soil, searching for tools and artifacts to complete the story. The samples they collect from the ice, called ice cores, hold a record of what our planet was like hundreds of thousands of years ago. But where do ice cores come from, and what do they tell us about climate change?
In some areas, these layers result in ice sheets that are several miles several kilometers thick. Researchers drill ice cores from deep sometimes more than a mile, or more than 1. They collect ice cores in many locations around Earth to study regional climate variability and compare and differentiate that variability from global climate signals.
The Greenland Ice Core holds a detailed record of climate for the last , years. Records such as this are important for understanding how the Earth’s climate.
Ice consists of water molecules made of atoms that come in versions with slightly different mass, so-called isotopes. Variations in the abundance of the heavy isotopes relative to the most common isotopes can be measured and are found to reflect the temperature variations through the year. The graph below shows how the isotopes correlate with the local temperature over a few years in the early s at the GRIP drill site:. The dashed lines indicate the winter layers and define the annual layers.
How far back in time the annual layers can be identified depends on the thickness of the layers, which again depends on the amount of annual snowfall, the accumulation, and how deep the layers have moved into the ice sheet. As the ice layers get older, the isotopes slowly move around and gradually weaken the annual signal. Read more about – diffusion of stable isotopes – how the DYE-3 ice core has been dated using stable isotope data – how stable isotope measurements are performed – stable isotopes as indicators of past temperatures – how annual layers are identified using impurity data.
Move the mouse over individual words to see a short explanation of the word or click on the word to go to the relevant page. For more information on the topic please contact Bo Vinther. Centre for Ice and Climate. Ice Core Drilling Projects. More information.
Ice Cores, Antarctica And Greenland
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None of the drilled Greenland ice cores (red dots) contains meteoritic grit trapped in the ice can be tied to dated ice cores drilled elsewhere.
Guest commentary from Jonny McAneney. You heard it here first …. Back in February, we wrote a post suggesting that Greenland ice cores may have been incorrectly dated in prior to AD This was based on research by Baillie and McAneney which compared the spacing between frost ring events physical scarring of living growth rings by prolonged sub-zero temperatures in the bristlecone pine tree ring chronology, and spacing between prominent acids in a suite of ice cores from both Greenland and Antarctica.
Last month, in an excellent piece of research Sigl et al. The clinching evidence was provided by linking tree-ring chronologies to ice cores through two extraterrestrial events…. In , Miyaki et al. The cause of this increase was possibly due to a very high energy solar proton event Usoskin et al. But 14 C is not the only cosmogenic isotope produced by such high energy events.
Ice core dating using stable isotope data
Ice cores are cylinders of ice drilled out of an ice sheet or glacier. Most ice core records come from Antarctica and Greenland, and the longest ice cores extend to 3km in depth. The oldest continuous ice core records to date extend , years in Greenland and , years in Antarctica. Ice cores contain information about past temperature, and about many other aspects of the environment.
A synchronized dating of three Greenland ice cores throughout the Holocene. Research output: Contribution to journal/Conference contribution in.
The NEEM ice core is only used for supporting match-point identification. Over the uppermost Tephra horizons provide an independent validation of our match points. In addition, we compare the ratio of annual layer thicknesses between ice cores in-between the match points to assess our results in view of the different ice-flow patterns and accumulation regimes of the different periods and geographical regions.
This initial timescale is the basis of interpretation and refinement of the presently derived EGRIP high-resolution data sets of chemical impurities. Annales Geophysicae. Atmospheric Measurement Techniques. Climate of the Past. Earth Surface Dynamics.
The International North Greenland Eemian Ice Drilling NEEM project results indicate that melting of Antarctic ice sheet may have contributed more to sea level rise than melting of the Greenland ice sheet some , years ago. This material is available primarily for archival purposes. Telephone numbers or other contact information may be out of date; please see current contact information at media contacts.
A new study that provides surprising details on changes in Earth’s climate from more than , years ago indicates that the last interglacial–the period between “ice ages”–was warmer than previously thought and may be a good analog for future climate, as greenhouse gases increase in the atmosphere and global temperatures rise. The research findings also indicate that melting of the massive West Antarctic ice sheet may have contributed more to sea-level rise at that time than melting of the Greenland ice sheet.
Members of the research team noted that they were working in Greenland during the summer of during a rare modern melt event similar to those discussed in the paper.
“Dating of Greenland ice cores by flow models, isotopes, volcanic debris, and continental dust.” Journal of Glaciology, Hammer, C.U., H.B. Clausen, and W.
The oldest ice core ever drilled outside the polar regions may contain ice that formed during the Stone Age — more than , years ago, long before modern humans appeared. Researchers from the United States and China are now studying the core — nearly as long as the Empire State Building is tall — to assemble one of the longest-ever records of Earth’s climate history. What they’ve found so far provides dramatic evidence of a recent and rapid temperature rise at some of the highest, coldest mountain peaks in the world.
The change is most noticeable on the Guliya Ice Cap, where they drilled the latest ice core. In this region, the average temperature has risen 1. Lonnie Thompson, Distinguished University Professor in the School of Earth Sciences at The Ohio State University and co-leader of the international research team, said that the new data lend support to computer models of projected climate changes. There, glaciologist Yao Tandong secured funding for a series of joint expeditions from the Chinese Academy of Sciences.
Continued warming in these regions will result in even more ice melt with the likelihood of catastrophic environmental consequences,” Yao noted. The name “Third Pole” refers to high mountain glaciers located on the Tibetan Plateau and in the Himalaya, in the Andes in South America, on Kilimanjaro in Africa, and in Papua, Indonesia — all of which have been studied by the Ohio State research team.
Of particular interest to the researchers is a projection from the Intergovernmental Panel on Climate Change that future temperatures on the planet will rise faster at high altitudes than they will at sea level. The warming at sea level is expected to reach 3 degrees Celsius by the year , and possibly double that, or 6 degrees Celsius, at the highest mountain peaks in the low latitudes.
Massive crater under Greenland’s ice points to climate-altering impact in the time of humans
Sune O. Rasmussen, A. Svensson and M. Polar ice cores reveal past climate change in ever-growing temporal resolution. Novel automated methods and improved manual annual layer identification allow for bipolar year-to-year investigations of climate events tens of thousands of years back in time. Ice cores from Antarctica, from the Greenland ice sheet, and from a number of smaller glaciers around the world yield a wealth of information on past climates and environments including unique records of past temperatures, atmospheric composition for example greenhouse gasses , volcanism, solar activity, dustiness, and biomass burning.
and volcanic ash: the importance of sparse tephras in Greenland ice cores. dated records from the Greenland GRIP, GISP2 and NGRIP ice cores for the past.
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Login Request new password. Register new account. Ethane measurements in Greenland ice cores: Developing a preindustrial record. General Organisation. University of California. University of California, Irvine, dept. Project start.
I was wondering how ice cores are dated accurately. I know Carbon 14 is one method, but some ice cores go back hundreds of thousands of years. Would other isotopes with longer half-lives be more accurate?
At least the upper parts of most Greenland ice cores have therefore been dated from thousands of δ18O samples that have been individually cut from the ice.
To support our nonprofit science journalism, please make a tax-deductible gift today. Soon, his target came into view: Hiawatha Glacier, a slow-moving sheet of ice more than a kilometer thick. It advances on the Arctic Ocean not in a straight wall, but in a conspicuous semicircle, as though spilling out of a basin. The helicopter landed near the surging river that drains the glacier, sweeping out rocks from beneath it. What he brought home clinched the case for a grand discovery.
Hidden beneath Hiawatha is a kilometer-wide impact crater, big enough to swallow Washington, D. The crater was left when an iron asteroid 1. Though not as cataclysmic as the dinosaur-killing Chicxulub impact , which carved out a kilometer-wide crater in Mexico about 66 million years ago, the Hiawatha impactor, too, may have left an imprint on the planet’s history.
The timing is still up for debate, but some researchers on the discovery team believe the asteroid struck at a crucial moment: roughly 13, years ago, just as the world was thawing from the last ice age.