774–775 carbon-14 spike

The 774–775 carbon-14 spike is an observed increase of around 1.2% in the concentration of the radioactive carbon-14 isotope in tree rings dated to 774 or 775 CE, which is about 20 times higher than the normal year-to-year variation of radiocarbon in the atmosphere. It was discovered during a study of Japanese cedar tree-rings, with the year of occurrence determined through dendrochronology.[1] A surge in beryllium-10 (10Be), detected in Antarctic ice cores, has also been associated with the 774–775 event.[2] The 774–775 CE carbon-14 spike is one of several Miyake events and it produced the largest and most rapid rise in carbon-14 ever recorded.[3][4]

The event appears to have been global, with the same carbon-14 signal found in tree rings from Germany, Russia, the United States, Finland, and New Zealand.[2][5][6]

The signal exhibits a sharp increase of around 1.2% followed by a slow decline, which is consistent with an instant production of carbon-14 in the atmosphere,[2] indicating that the event was short in duration. The globally averaged production of carbon-14 for this event is (1.3 ± 0.2) × 108 atoms/cm2.[2][7][8]

  1. ^ Cite error: The named reference nature was invoked but never defined (see the help page).
  2. ^ a b c d e Cite error: The named reference usoskin was invoked but never defined (see the help page).
  3. ^ Reimer, Paula; et al. (August 2020). "The IntCal20 Northern Hemisphere Radiocarbon Age Calibration Curve (0–55 cal kBP)". Radiocarbon. 62 (4): 725–757. Bibcode:2020Radcb..62..725R. doi:10.1017/RDC.2020.41. hdl:1893/30981. S2CID 216215614.
  4. ^ University of Kansas (November 30, 2012). "Researcher points to Sun as likely source of eighth-century 'Charlemagne event'".
  5. ^ Cite error: The named reference jull was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference guettler was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference melott was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference pavlov was invoked but never defined (see the help page).
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