Eleven-year solar cycles over the last millennium revealed by radiocarbon in tree rings

Nicolas Brehm, Alex Bayliss, Marcus Christl, Hans Arno Synal, Florian Adolphi, Jürg Beer, Bernd Kromer, Raimund Muscheler, Sami K. Solanki, Ilya Usoskin, Niels Bleicher, Silvia Bollhalder, Cathy Tyers, Lukas Wacker

Forskningsoutput: TidskriftsbidragArtikel i vetenskaplig tidskriftPeer review

34 Citeringar (SciVal)


The Sun provides the principal energy input into the Earth system and solar variability represents a significant external climate forcing. Although observations of solar activity (sunspots) cover only the last about 400 years, radionuclides produced by cosmic rays and stored in tree rings or ice cores serve as proxies for solar activity extending back thousands of years. However, the presence of weather-induced noise or low temporal resolution of long, precisely dated records hampers cosmogenic nuclide-based studies of short-term solar variability such as the 11-yr Schwabe cycle. Here we present a continuous, annually resolved atmospheric 14C concentration (fractionation-corrected ratio of 14CO2 to CO2) record reconstructed from absolutely dated tree rings covering nearly all of the last millennium (ad 969–1933). The high-resolution and precision 14C record reveals the presence of the Schwabe cycle over the entire time range. The record confirms the ad 993 solar energetic particle event and reveals two new candidates (ad 1052 and ad 1279), indicating that strong solar events that might be harmful to modern electronic systems probably occur more frequently than previously thought. In addition to showing decadal-scale solar variability over the last millennium, the high-temporal-resolution record of atmospheric radiocarbon also provides a useful benchmark for making radiocarbon dating more accurate over this interval.

Sidor (från-till)10-15
Antal sidor6
TidskriftNature Geoscience
StatusPublished - 2021

Ämnesklassifikation (UKÄ)

  • Geologi


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