Multiradionuclide evidence for an extreme solar proton event around 2,610 B.P. (∼660 BC)

Research output: Contribution to journalArticle


Recently, it has been confirmed that extreme solar proton events can lead to significantly increased atmospheric production rates of cosmogenic radionuclides. Evidence of such events is recorded in annually resolved natural archives, such as tree rings [carbon-14 ( 14 C)] and ice cores [beryllium-10 ( 10 Be), chlorine-36 ( 36 Cl)]. Here, we show evidence for an extreme solar event around 2,610 years B.P. (∼660 BC) based on high-resolution 10 Be data from two Greenland ice cores. Our conclusions are supported by modeled 14 C production rates for the same period. Using existing 36 Cl ice core data in conjunction with 10 Be, we further show that this solar event was characterized by a very hard energy spectrum. These results indicate that the 2,610-years B.P. event was an order of magnitude stronger than any solar event recorded during the instrumental period and comparable with the solar proton event of AD 774/ 775, the largest solar event known to date. The results illustrate the importance of multiple ice core radionuclide measurements for the reliable identification of short-term production rate increases and the assessment of their origins.


External organisations
  • Lund University
  • University of Bern
  • University of Paris-Saclay
  • United Arab Emirates University
  • Eawag: Swiss Federal Institute of Aquatic Science and Technology
  • ETH Zürich
  • University of California, Irvine
  • Aix-Marseille University
  • Korea Institute of Geoscience and Mineral Resources
  • Uppsala University
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Geosciences, Multidisciplinary


  • Ice cores, Radionuclides, Solar proton events, Solar storms
Original languageEnglish
Pages (from-to)5961-5966
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number13
Publication statusPublished - 2019
Publication categoryResearch