Radiocarbon dating becomes more accurate than ever after an international team of scientists refined the technique of evaluating the age of historical objects.
The team of researchers at the Universities of Sheffield, Belfast, Bristol, Glasgow, Oxford, St Andrews and Historic England, together with international colleagues, used measurements from nearly 15,000 samples from dating objects. about 60,000 years ago, as part of seven-year projects.
They used the measurements to create new International Radioactive Carbon Calibration Curves (IntCal), which are the baseline in the scientific spectrum to accurately date artifacts and make predictions of future. 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 historical sites or study the fall of the Neanderthals, while geologists on the Intergovernmental Panel on Climate Change ( IPCC), relying on curves to learn about past climates to better understand and prepare for future changes.
Professor Paula Reimer, from Queen̵7;s Belfast University and head of the IntCal project, said: “Radiocarbon dating has revolutionized the field of archeology and environmental science. . As we improve the baseline, we learn more about our history. IntCal calibration curves are key to helping answer major questions about the environment and where we are in it.
The team of researchers has developed three curves depending 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. Development in this field has helped us to truly improve our understanding. I look forward to seeing the new insights into our past that these recalculated radioactive carbon intervals provide.
Radioactive carbon calibration curves have been developed in the past 50 years, mainly based on measurements taken from 10 to 20 year old blocks of wood that are large enough to test for radioactive carbon.
Advances in radioactive carbon testing mean updated curves instead employ small patterns, such as tree rings that cover only a year, providing precision and detail not previously possible. 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 14C level 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 variation to accurately convert 14C measurements into calendar ages. 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 using a different method. 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 radiometric carbon measurements taken from objects that are 60,000 years old.
Alex Bayliss, Head of Scientific Chronology at Historic England, said: “The highly precise and highly precise radiocarbon dating underlies the public’s interest in the lips. School history and allows for better preservation and protection.
“The new curves are of international importance for archeological methods, and for conservation practices and understanding of the heritage built of wood.”
“The IntCal curve series is critical to providing a perspective on past climate, which is essential for our understanding of climate systems and as a baseline for modeling,” said Darrell Kaufman of the IPCC. change in the future. ”