C05_04

Current compilation of recent atmospheric radiocarbon

Hua Q¹, Turnbull J^2,3, Santos G⁴, Rakowski A⁵, Ancapichún S^6,7, De Pol-Holz R⁷, Hammer S⁸, Lehman S⁹, Levin I⁸, Miller J¹⁰, Palmer J^11,12, Turney C¹³

¹Australian Nuclear Science And Technology Organisation, Lucas Heights, Australia, ²Rafter Radiocarbon Laboratory, GNS Science, Lower Hutt, New Zealand, ³CIRES, University of Colorado , Boulder, USA, ⁴Earth System Science, University of California, Irvine, , USA, ⁵Institute of Physics, Center for Science and Education, Silesian University of Technology, Gliwice, Poland, ⁶Postgraduate School in Oceanography, Faculty of Natural and Oceanographic Sciences, Universidad de Concepción, Concepción, Chile, ⁷Centro de Investigación GAIA Antártica (CIGA) and Network for Extreme Environment Research (NEXER), Universidad de Magallanes, Punta Arenas, Chile, ⁸Institut für Umweltphysik, Heidelberg University , Heidelberg, Germany, ⁹INSTAAR, University of Colorado,, Boulder, USA, ¹⁰NOAA Global Monitoring Laboratory, Boulder, USA, ¹¹ARC Centre of Excellence for Australian Biodiversity and Heritage, School of Biological, Earth and Environmental Sciences, University of New South Wales, , Australia, ¹²Chronos 14Carbon-Cycle Facility and the Earth and Sustainability Science Research Centre, University of New South Wales, , Australia, ¹³Division of Research, University of Technology Sydney, , Australia

The last couple of centuries has seen substantial changes in atmospheric radiocarbon driven by the combustion of fossil fuels free of ¹⁴C since the mid-19th century and the injection of bomb-derived radiocarbon into the atmosphere, mostly in the late 1950s and early 1960s. The current compilation of recent atmospheric radiocarbon levels, covering the period from 1950 to 2019, was released late last year. It consists of zonal, hemispheric and global summer data sets for use in carbon-cycle studies and monthly data sets for five zones (Northern Hemisphere zones 1, 2, and 3, and Southern Hemisphere zones 3 and 1-2) for more accurate radiocarbon dating of recent terrestrial samples. After describing the current compilation, the presentation will focus on new and future collections. This discussion includes new data sets such as atmospheric sampling from Alert and Neumayer (Levin et al., 2021), tree rings from Eastern Amazon Basin (Santos et al., in prep.) and southern Chile (De Pol-Holz et al., in prep.). The new data enables the extension to a more recent time period and the improved determination of zonal borders. Autumn and winter plant/seed data during the early bomb period (e.g., Hüls et al. 2021), where atmospheric sampling is not available, can allow an improved compilation of monthly zonal data. Finally, data quality considerations, such as applying dendrochronological methods, tree-ring pre-treatment and replicate radiocarbon analyses, will also be discussed.

Hüls, M. et al. 2021. Radiocarbon 63, 1387-1396.

Levin, I. et al. 2021. Radiocarbon, doi:10.1017/RDC.2021.102