The radiocarbon encounter is set to become more accurate than ever after an international team of scientists improved the technique for estimating the age of historic sites.
The team of researchers at the Universities of Sheffield, Belfast, Bristol, Glasgow, Oxford, St Andrews and Historic England, plus international colleagues, used measurements from almost 15,000 samples from objects dating back up to 60,000 years ago, as part of a seven-project year.
They used measurements to create new international radiocarbon calibration (IntCal) curves, which are essential across the scientific spectrum for accurately dating objects and making predictions for the future. Meeting with radiocarbon is essential for fields such as archeology and geoscience to date everything from the oldest modern human bones to historical climate models.
Archaeologists can use that knowledge to restore historic monuments or study Neanderthal decay, while geoscientists on the Intergovernmental Panel on Climate Change (IPCC) rely on curves to learn what the climate was like in the past to better understand and prepare for future changes.
Professor Paula Reimer, of Queen̵7;s University in Belfast and head of the IntCal project, said: “Radiocarbon dating has revolutionized the field of archeology and environmental science. As we improve the calibration curve, we learn more about our history. IntCal calibration curves are essential to help answer the big questions about the environment and our place within it. “
The team of researchers has developed three turns depending on the location of the object to be dated. New curves, to be published in radiocarbon, 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 on the Marine Curve20, said: “This is a very exciting time to work on radiocarbon. Developments in this area have made it possible for us to really advance our understanding. I look forward to seeing. what these recalculated radiocarbon durations give new insights into our past. ”
The radiocarbon calibration curves developed over the past 50 years were very much based on measurements taken from pieces of wood covering 10-20 years large enough to be tested for radiocarbon.
Advances in radiocarbon testing mean updated curves, instead, use smaller samples, such as tree rings covering only single years, that provide precision and detail previously impossible in new calibration turns. Moreover, improvements in understanding the carbon cycle have meant that curves are now extended to the limit of the radiocarbon technique, 55,000 years ago.
Radiocarbon dating is the most widely used dating approach of the last 55,000 years and supports archaeological and environmental science. It was first developed in 1949. It depends on two carbon isotopes called stable 12C and radioactive 14C.
While a plant or animal is alive, it receives new carbon, so it has the same ratio of these isotopes as the atmosphere at that time. But after an organism dies, it stops taking in new carbon, stable 12C remains, but 14C rots at a known rate. By measuring the ratio of 14C to 12C left in an object, the date of its death can be estimated.
If the atmospheric 14C level were constant, this would be easy. However, it has fluctuated significantly throughout history. In order to date organisms accurately scientists need a reliable historical record of its variation to accurately translate 14C measurements into calendar epochs. The new IntCal curves offer this connection.
Curves are created based on the collection of a large number of archives that store past radiocarbon, but can also be dated using another method. Such archives include tree rings from up to 14,000 years ago, stalagmites found in caves, corals from the sea, and nuclei drilled by lake and ocean sediments. In total, the new curves were based on almost 15,000 radiocarbon measurements taken from objects as old as 60,000 years.
Alex Bayliss, Head of Scientific Meetings in Historic England, said: “Precise and high-precision dates underscore public satisfaction with the historic environment and provide better preservation and protection.
“The new curves have important international implications for archaeological methodology and practices in the preservation and understanding of wood-built heritage.”
Darrell Kaufman of the IPCC said: “The IntCal turn series are essential to provide a perspective on the past climate, which is essential to our understanding of the climate system, and an initial basis for modeling future change.”
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