Skip to main content Accessibility help


  • Sabrina G K Kudsk (a1), Bente Philippsen (a2) (a3), Claudia Baittinger (a4), Alexandra Fogtmann-Schulz (a1), Mads F Knudsen (a1), Christoffer Karoff (a1) (a5) and Jesper Olsen (a2) (a3)...


Single-year measurements of radiocarbon (14C) in tree rings have led to the discovery of rapid cosmic-ray events as well as longer lasting anomalies, which have given new insights into the Sun’s behavior in the past. Here, we present two new single-year 14C records based on Danish oak that span the periods AD 692–790 and 966–1057, respectively, and consequently include the two rapid cosmic-ray events in AD 775 and 994. The new data are presented along with relevant information on the dendrochronological dating of the wood pieces, implying that these new measurements may contribute towards generating the next international calibration curve. The new data covering the AD 966–1057 period suggest that the increase in atmospheric 14C associated with the cosmic-ray event in AD 994 actually occurred in AD 993, i.e. one year earlier than the year reported in Fogtmann-Schulz et al. (2017) based on oak from southern Denmark. Careful reanalysis of the dendrochronology that underpins the new 14C records based on oak material from southern Denmark reveals that the cosmic-ray event reported in Fogtmann-Schulz et al. (2017) actually took place in AD 993.


Corresponding author

*Corresponding author. Email:


Hide All
Baillie, M, Pilcher, J. 1973. A simple cross-dating program for tree-ring research. Tree-Ring Bulletin 33:714.
Baittinger, C. 2009. Præliminær dendrokronologisk undersøgelse II af træprøver fra Ravning Enge. Nationalmuseets Naturvidenskabelige Undersøgelser NNU rapport 3.
Bevington, PR, Robinson, DK. 2003. Data reduction and error analysis for the physical sciences. 3rd ed. Boston (MA): McGraw-Hill.
Bonde, N. 1992. Dendrokronologisk undersøgelse af træprøver fra spærring i Haderslev Fjord Nationalmuseets Naturvidenskabelige Undersøgelser NNU rapport 14.
Damon, PE, Kaimei, D, Kocharov, GE, Mikheeva, IB, Peristykh, AN. 1995. Radiocarbon production by the gamma-ray component of supernova explosions. Radiocarbon 37(2):599604.
Dee, M, Pope, B, Miles, D, Manning, S, Miyake, F. 2017. Supernovae and single-year anomalies in the atmospheric radiocarbon record. Radiocarbon 59(2):293302.
Eriksen, OH. 1998. Dendrokronologisk undersøgelse af træ fra udgravning ved Gråbrødre kloster, Randers. Dendrokronologisk Laboratorium NNU rapport 38.
Eriksen, OH. 1999. ”Østergård”, Haderslev Amt. Dendrokronologisk Laboratorium NNU rapport 24.
Eriksen, OH. 2004. Dendrokronologisk undersøgelse af træ fra vadested ved Mojbøl i Sønderjyllands amt. Nationalmuseets Naturvidenskabelige Undersøgelser NNU rapport 2.
Fogtmann-Schulz, A, Østbø, SM, Nielsen, SGB, Olsen, J, Karoff, C, Knudsen, MF. 2017. Cosmic ray event in 994 C.E. recorded in radiocarbon from Danish oak. Geophysical Research Letters 44:86218628.
Gray, LJ, Beer, J, Geller, M, Haigh, JD, Lockwood, M, Matthes, K, Cubasch, U, Fleitmann, D, Harrison, G, Hood, L, et al. 2010. Solar influence on climate. Reviews of Geophysics 48:RG4001.
Güttler, D, Wacker, L, Kromer, B, Friedrich, M, Synal, H-A. 2013. Evidence of 11-year solar cycles in tree-rings from 1010 to 1110 AD – progress on high precision AMS measurements. Nuclear Instruments and Methods in Physics Research B 294:459463.
Güttler, D, Adolphi, F, Beer, J, Bleicher, N, Boswijk, G, Christl, M, Hogg, A, Palmer, J, Vockenhuber, C, Wacker, L, Wunder, J. 2015. Rapid increase in cosmogenic 14C in AD 775 measured in New Zealand kauri trees indicates short-lived increase in 14C production spanning both hemispheres. Earth and Planetary Science Letters 411:290297.
Jacobsson, P, Hamilton, WD, Cook, G, Crone, A, Dunbar, E, Kinch, H, Naysmith, P, Tripney, B, Xu, S. 2017. Refining the Hallstatt Plateau: short-term 14C variability and small scale offsets in 50 consecutive single tree-rings from southwest Scotland dendro-dated to 510–460 BC. Radiocarbon 60(1):219237.
Jull, AJT, Panyushkina, IP, Lange, TE, Kukarskih, VV, Myglan, VS, Clark, KJ, Salzer, MW, Burr, GS, Leavitt, SW. 2014. Excursions in the 14C record at AD 774–775 in tree rings from Russia and America. Geophysical Research Letters 41:30043010.
Jull, AJT, Panyuskina, I, Miyake, F, Masuda, K, Nakamura, T, Mitsutani, T, Lange, TE, Cruz, RJ, Baisan, C, Janovic, R, Varga, T, Molnár, M. 2018. More rapid 14C excursions in the tree-ring record: a record of different kind of solar activity at about 800 BC? Radiocarbon 60(4):12371248.
Kudsk, S, Olsen, J, Nielsen, L, Fogtmann-Schulz, A, Knudsen, M, Karoff, C. 2018. What is the carbon origin of early-wood? Radiocarbon 60(5):14571464.
Loader, NJ, Robertson, I, Barker, AC, Switsur, VR, Waterhouse, JS. 1997. An improved technique for the batch processing of small wholewood samples to α-cellulose. Chemical Geology 136:313317.
Marshall, P, Bayliss, A, Farid, S, Tyers, C, Bronk Ramsey, C, Cook, G, Doğan, T, Freeman, SPHT, İlkmen, E, Knowles, T. 2018. 14C wiggle-matching of short tree-ring sequences from post-medieval buildings in England. Nuclear Instruments and Methods in Physics Research B. in press.
Menjo, H, Miyahara, H, Kuwana, K, Masuda, K, Nakamura, T. 2005. Possibility of the detection of past supernova explosion by radiocarbon measurement. 29th International Cosmic Ray Conference Pune 2:357–360.
Miyake, F, Nagaya, K, Masuda, K, Nakamura, T. 2012. A signature of cosmic-ray increase in AD 774–775 from tree rings in Japan. Nature 486(7402):240242.
Miyake, F, Masuda, K, Nakamura, T. 2013. Another rapid event in the carbon-14 content of tree rings. Nature Communications 4.
Miyake, F, Masuda, K, Hakozaki, M, Nakamura, T, Tokanai, F, Kato, K, Kimura, K, Mitsutani, T. 2014. Verification of the Cosmic-Ray Event in AD 993–994 by using a Japanese Hinoki tree. Radiocarbon 56(3):11891194.
Miyake, F, Jull, AJT, Panyushkina, IP, Wacker, L, Salzer, M, Baisen, CH, Lange, T, Cruz, R, Masuda, K, Nakamura, T. 2017a. Large 14C excursion in 5480 BC indicates and abnormal sun in the mid-Holocene. PNAS 114(5):881884.
Miyake, F, Masuda, K, Nakamura, T, Kimura, K, Hakozaki, M, Jull, A, Lange, TE, Cruz, R, Panyushkina, IP, Baisan, C, Salzer, MW. 2017b. Search for annual 14C excursions in the past. Radiocarbon 59(2):315320.
Olsen, J, Tikhomirov, D, Grosen, C, Heinemeier, J, Klein, M. 2017. Radiocarbon analysis on the new AARAMS 1MV Tandetron. Radiocarbon 59(3):905913.
Park, J, Southon, J, Fahrni, S, Creasman, PP, Mewaldt, R. 2017. Relationship between solar activity and Δ14C peaks in AD 775, AD 994, and 660 BC. Radiocarbon 59(4):11471156.
Pearson, CL, Brewer, PW, Brown, D, Heaton, TJ, Hodgins, GWL, Jull, AJT, Lange, T, Salzer, MW. 2018. Annual radiocarbon record indicates 16th century BCE date for the Thera eruption. Science Advances 4(8):eaar8241.
Rakowski, AZ, Krąpiec, M, Huels, M, Pawlyta, J, Dreves, A, Meadows, J., 2015. Increase of radiocarbon concentration in tree rings from Kujawy (SE Poland) around AD 774–775. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 361:564–8.
Reimer, PJ, Bard, E, Bayliss, A, Beck, JW, Blackwell, PG, Bronk Ramsey, C, Buck, CE, Cheng, H, Edwards, RL, Friedrich, M, et al. 2013. IntCal13 and Marine13 radiocarbon age calibration curves 0–50,000 years cal BP. Radiocarbon 55(4):18691887.
Sakamoto, M, Imamura, M, Van der Plicht, J, Mitsutani, T, Sahara, M. 2003. Radiocarbon calibration for Japanese wood samples. Radiocarbon 45(1):8189.
Sakamoto, M, Hakozaki, M, Nakao, N, Nakatsuka, T. 2017. Fine structure and reproducibility of radiocarbon ages of middle to early modern Japanese tree rings. Radiocarbon 59(6):19071917.
Southon, JR, Magana, AL. 2010. A comparison of cellulose extraction and ABA pretreatment methods for AMS 14C dating of ancient wood. Radiocarbon 52(3):13711379.
Stuiver, M, Polach, HA. 1977. Reporting of 14C data. Radiocarbon 19(3):355363.
Tyers, I. 1999. DENDRO for Windows Program Guide. Sheffield, U.K.: University of Sheffield; ARCUS report 500.
Usoskin, IG, Kromer, B, Ludlow, F, Beer, J, Friedrich, M, Kovaltso, GA, Solanki, SK, Wacker, L. 2013. The AD 775 cosmic event revisited: the Sun is to blame. Astronomy & Astrophysics 552:L3.
Wacker, L, Güttler, D, Goll, J, Hurni, JP, Synal, H-A, Walti, N. 2014. Radiocarbon dating to a single year by means of rapid atmospheric 14C changes. Radiocarbon 56(2):573579.
Wang, FY, Yu, H, Zou, YC, Dai, ZG, Cheng, KS. 2017. A rapid cosmic-ray increase in BC 3372–3371 from ancient buried tree-rings in China. Nature Communications 8:1487.


Type Description Title
Supplementary materials

Kudsk et al. supplementary material
Kudsk et al. supplementary material

 Unknown (28 KB)
28 KB


  • Sabrina G K Kudsk (a1), Bente Philippsen (a2) (a3), Claudia Baittinger (a4), Alexandra Fogtmann-Schulz (a1), Mads F Knudsen (a1), Christoffer Karoff (a1) (a5) and Jesper Olsen (a2) (a3)...


Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed