Radiocarbon dating becomes more accurate than ever after an international team of scientists refined the technique of age assessment of historical objects.
The team of researchers at the University of Sheffield, Belfast, Bristol, Glasgow, Oxford, St Andrews and Historic England, plus international colleagues, used measurements from nearly 15,000 samples from objects dating back 60,000 years ago, as part of seven-year projects.
They used the measurements to create new International Radioactive Carbon Calibration Curves (IntCal), the baseline in the scientific spectrum to accurately date artifacts and make predictions of similarities. hybrid. Radiocarbon dating is important for fields like archeology and geological sciences to date everything from oldest modern human bones to historical climates.
Archaeologists can use that knowledge to restore historic sites or study the fall of the Neanderthals, while geologists on the Intergovernmental Panel on Climate Change (IPCC), relies on curves to learn about past climate to better understand and prepare for future changes.
Professor Paula Reimer, from Queen’s Belfast University and head of the IntCal project, said: “Radiocarbon dating has revolutionized the field of archeology and environmental science. As we improve our baselines, we learn more about our history. IntCal baselines are key to helping answer the big environmental questions and where we are in them. “
The team of researchers has developed three curves that depend on where the dated object is found. The new curves, will be published in Radioactive carbon, are IntCal20 for the Northern Hemisphere, SHCal20 for the Southern Hemisphere and Marine20 for the world’s oceans.
Dr. Tim Heaton, from the University of Sheffield and lead author of the Marine20 curve, said: “This is a very exciting time to be working in radioactive carbon. The developments in this field have helped us to make real. I look forward to seeing new insights into our past that these recalculated radiocarbon intervals provide. “
Radiocarbon reference curves have been developed in the past 50 years, relying mainly on measurements taken from 10 to 20 years of wood-covered blocks large enough to test for radioactive carbon.
Advances in radioactive carbon testing mean updated curves instead employ small patterns, such as tree rings covering only a year, providing unprecedented accuracy and detail here in the new calibration curves. In addition, the improvement in the understanding of the carbon cycle means that curves have now been extended to the limits of radioactive carbon engineering 55,000 years ago.
Radiocarbon dating is the most frequently used approach to dating over the past 55,000 years and underpins archeological and environmental science. It was first developed in 1949. It depends on two isotopes of carbon known as 12C stabilization and 14C radioactive.
While the plant or animal is alive, it will absorb the new carbon, so there was the same ratio between the isotopes and the atmosphere at that time. But when an organism dies, it stops absorbing new carbon, the stable 12C remains but the 14C decomposes at a known rate. By measuring the ratio of 14C to 12C remaining in an object it is possible to estimate its death date.
If the level of 14C in the atmosphere is constant, this should be easy. However, it has fluctuated significantly throughout history. To accurately date organisms, scientists need a reliable historical record of its transformation to accurately convert 14C measurements into calendar age. New IntCal curves provide this link.
The curves are created based on the collection of large amounts of radioactive carbon archives in the past but can also be dated by other methods. Such archives include tree rings from 14,000 years ago, stalagmites found in caves, corals from the sea, and cores drilled from lake and ocean sediments. In total, the new curves are based on nearly 15,000 radioactive carbon measurements taken from objects 60,000 years old.
Alex Bayliss, Head of the Scientific Department of Dating at Historic England, said: “Highly accurate and precise radiocarbon dating provide the basis for public interest in historical environments and allows for better preservation and protection.
“The new curves are of international importance to archeological and practical methods in conservation and understanding of the heritage built by wood.”
“The IntCal curve series is critical to providing a perspective on past climate, which is essential for our understanding of the climate system and as a baseline for modeling,” said Darrell Kaufman of the IPCC. change in the future. ”
Research clarifies inaccuracies in radiocarbon dating
Paula J Reimer et al. AGE GUIDELINES INTCAL20 HEMISPHERE RADIOCARBON (0–55 CAL kBP), Radioactive carbon (Year 2020). DOI: 10.1017 / RDC.2020.41
Provided by Sheffield University
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