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Edited by Konrad A. Hughen, Woods Hole Oceanographic Institute, Woods Hole, MA, and accepted by the Editorial Board October 8, 2010 (received for review January 6, 2010)
Abstract
The Maunder Minimum (A.D. 1645–1715) is a useful period to investigate possible sun–climate linkages as sunspots became exceedingly rare and the characteristics of solar cycles were different from those of today. Here, we report annual variations in the oxygen isotopic composition (δ18O) of tree-ring cellulose in central Japan during the Maunder Minimum. We were able to explore possible sun–climate connections through high-temporal resolution solar activity (radiocarbon contents; Δ14C) and climate (δ18O) isotope records derived from annual tree rings. The tree-ring δ18O record in Japan shows distinct negative δ18O spikes (wetter rainy seasons) coinciding with rapid cooling in Greenland and with decreases in Northern Hemisphere mean temperature at around minima of decadal solar cycles. We have determined that the climate signals in all three records strongly correlate with changes in the polarity of solar dipole magnetic field, suggesting a causal link to galactic cosmic rays (GCRs). These findings are further supported by a comparison between the interannual patterns of tree-ring δ18O record and the GCR flux reconstructed by an ice-core 10Be record. Therefore, the variation of GCR flux associated with the multidecadal cycles of solar magnetic field seem to be causally related to the significant and widespread climate changes at least during the Maunder Minimum.
- solar forcing of climate
- little ice age
- paleoclimate reconstruction
- grand solar minimum
- tree-ring isotope climatology
Footnotes
- 1To whom correspondence should be addressed. E-mail: yokoyama{at}aori.u-tokyo.ac.jp.
Author contributions: Y.Y. and H.M. designed research; Y.T.Y., K.S., and T.N. performed research; T.N. contributed new reagents/analytic tools; Y.T.Y., Y.Y., and H.M. analyzed data; and Y.T.Y., Y.Y., and H.M. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission. K.A.H. is a guest editor invited by the Editorial Board.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1000113107/-/DCSupplemental.
Synchronized Northern Hemisphere climate change and solar magnetic cycles during the Maunder Minimum
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- Physical Sciences
- Environmental Sciences
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