Evidence for solar-flare and other cosmic-ray events in the 14C record in tree rings: New information and a cautionary tale.
- 1University of Arizona, Geosciences, Tucson, United States of America (jull@email.arizona.edu)
- 2Isotope Climatology and Environmental Research Centre, Institute for Nuclear Research, Debrecen, Hungary
- 3Laboratory for Tree-Ring Research, University of Arizona, Tucson, AZ, USA
- 4Institute for Space-Earth Environment Research, University of Nagoya, Japan
- 5Laboratory for Ion Beam Physics, ETH-Zürich, Switzerland
- 6Chair of Forest Growth and Dendrochronology, University of Freiburg, Germany
Excursions in the radiocarbon (14C) record, which are rapid changes on a scale of a few years are presumed to be caused by an increase of incoming cosmic rays. The excursions at AD 774-775AD and 993-994AD have generated widespread interest and have been reproduced in many different tree-ring records (Miyake et al. 2012, 2013, 2017; Büntgen et al. 2018). Similar structures have also been detailed, such as at 660BC (Park et al. 2017; O’Hare et al. 2019). Other types of change in 14C production may be due to a mix of SPE and different phenomena, such as around 5480BC (Miyake et al. 2017) and 815BC (Jull et al. 2018). We note that a proposed SPE event about 3371BC (Wang et al. 2018) is currently unconfirmed and this emphasizes the need for an anchored dendro-record to determine possible events. Timing of these events is important to understand the underlying recurrence intervals. A considerable number of processes can affect the cosmic-ray flux, including solar events, gamma-ray bursts, geomagnetic shifts and relatively close supernovae. Such studies are providing a wealth of new information through which to characterize new ‘events’ in 14C structure and to begin to understand the processes behind them. These effects also have introduced more complexity to the international radiocarbon calibration curve.
This research was supported in part by the European Union and the State of Hungary, co-financed by the European Regional Development Fund in the project of GINOP-2.3.2-15-2016-00009 ‘ICER’.
References: Büntgen et al. 2018. Nature Communications 9: 3605; A. J. T. Jull et al. 2014. Geophysics Research Letters 41: 3004-3010; F. Miyake et al. 2012. Nature 486: 282-284; F. Miyake et al. 2013. Nature Communications 4: 1748; F. Miyake et al. 2017. PNAS 114: 881-884; P. O’Hare et al. 2019. PNAS 116: 5961-5966; J. Park et al. 2017. Radiocarbon 59: 1147-1156; F. Y. Wang et al. Nature Communications 18: 1487.
How to cite: Jull, A., Panyushkina, I., Miyake, F., Salzer, M., Baisan, C., Molnar, M., Varga, T., Wacker, L., Brehm, N., and Tegel, W.: Evidence for solar-flare and other cosmic-ray events in the 14C record in tree rings: New information and a cautionary tale., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5377, https://doi.org/10.5194/egusphere-egu2020-5377, 2020
