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

TY - JOUR

T1 - Eleven-year solar cycles over the last millennium revealed by radiocarbon in tree rings

AU - Brehm, Nicolas

AU - Bayliss, Alex

AU - Christl, Marcus

AU - Synal, Hans Arno

AU - Adolphi, Florian

AU - Beer, Jürg

AU - Kromer, Bernd

AU - Muscheler, Raimund

AU - Solanki, Sami K.

AU - Usoskin, Ilya

AU - Bleicher, Niels

AU - Bollhalder, Silvia

AU - Tyers, Cathy

AU - Wacker, Lukas

PY - 2021

Y1 - 2021

N2 - 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.

AB - 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.

U2 - 10.1038/s41561-020-00674-0

DO - 10.1038/s41561-020-00674-0

M3 - Article

AN - SCOPUS:85098800457

VL - 14

SP - 10

EP - 15

JO - Nature Geoscience

JF - Nature Geoscience

SN - 1752-0908

IS - 1

ER -