Australia: The Land Where Time Began

A biography of the Australian continent 

Early Younger Dryas - Variations of atmospheric ¹⁴C Derived from Tree Rings

Over the interval of the Younger Dryas, about 13,000 - 11,600 cal yr BP, variations in atmospheric radiocarbon reveal crucial information about linkages between climate, ocean circulation and carbon cycles, which makes them of immense scientific interest. According to the authors¹ there is  no direct and reliable evidence available of atmospheric ¹⁴C that is based on tree rings for the entire Younger Dryas. The authors¹ have presented in this paper high-precision measurements of ¹⁴ C, extending the absolute tree ring chronology from 12,400 to 12,550 cal yr BP and a high-precision, high-resolution record of atmospheric ¹⁴C that was derived from a 617 year tree ring chronology of Huon pine in Tasmania, Australia, that spans the early Younger Dryas. The current gap in European tree ring radiocarbon chronologies during the early Younger Dryas is bridged by the new ¹⁴C records, which links the floating late glacial pine record to the absolute tree ring timescales. The result is a continuous, reliable atmospheric ¹⁴C record that covers the past 14,000 cal yr BP, including the Younger Dryas. It is indicated by the new records that the abrupt atmospheric Δ¹⁴C rise associated with the onset of the Younger Dryas occurs at about 12,760 cal yr BP, which is about 240 years later than that recorded in the Cariaco varves, with a smaller magnitude of about 40 ‰, which was followed by several centennial Δ¹⁴C variations of 20-25 ‰. When the tree ring Δ¹⁴C is compared to Δ¹⁴C that is marine-derived and modeled Δ¹⁴C, that is based on ice core ¹⁰Be fluxes, the authors¹ concluding that ocean circulation changes and production rate of Δ¹⁴C were responsible for variations of the atmospheric Δ¹⁴C for the remainder of the Younger Dryas.

Sources & Further reading

1. Hua, Quan, Mike Barbetti, David Fink, Klaus Felix Kaiser, Michael Friedrich, Bernd Kromer, Vladimir A. Levchenko, et al. "Atmospheric 14c Variations Derived from Tree Rings During the Early Younger Dryas." Quaternary Science Reviews 28, no. 25–26 (12// 2009): 2982-90.