Abstract
Time series of annual Δ14C and δ13C in tree rings of Sequoiadendron giganteum, AD 998-1510, are similar in form. The Δ14C series completes, with data of Stuiver and Braziunas (1993), a 957-yr time-series. Discrete Fourier transformation of detrended Δ14C reveals periods of 126, 91, 56, 17.6, 13.6, 10.4, and 7.1 yr. Non-random differences exist between decadal averages of the Sequoiadendron Δ14C data and data of Stuiver and Becker (1993). Periods of 7-17 yr may correspond to Schwabe or related climatic cycles; these have 10-17-yr periods and amplitudes < 6‰ (AD 1100-1250), and periods near 7 yr with amplitudes up to 10‰ (AD 1380-1420). Abrupt increases in Δ14C are mainly less than 5‰, and do not constitute convincing evidence of increased 14C production from supernovae or solar proton events. The δ13C time-series is likely to reflect climate change, and for centennial periodicity lags behind Δ14C by 20-40 yr (centennial time-scale) and 25-50 yr (millennial). Phase-shifts between solar luminosity and surface Δ14C are 125-175 yr and 20 yr for millennial and centennial cycles, respectively. The study suggests that strongest climate effects may therefore follow peak luminosity by 125-175 yr for millennial cycles and 20-40 yr for centennial cycles.
Original language | English (US) |
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Pages (from-to) | 661-680 |
Number of pages | 20 |
Journal | Radiocarbon |
Volume | 61 |
Issue number | 3 |
DOIs | |
State | Published - Jun 1 2019 |
Keywords
- carbon-13
- carbon-14
- climate change
- solar cycles
- tree rings
ASJC Scopus subject areas
- Archaeology
- General Earth and Planetary Sciences