Abstract

A 2100-yr decadal-resolution salinity and aridity proxy record of lacustrine ostracode-shell Mg/Ca ratios from a closed-basin lake in the northern Great Plains shows statistically significant periodicities of ∼400, 200, 130, and 100 yr. These periodicities are similar to the three principal solar-oscillation periods (420, 218, 143 yr) as inferred from the atmospheric radiocarbon record, suggesting strong solar forcing of century-scale drought frequency with a fundamental 400-yr period and its 2nd, 3rd, and 4th harmonics. Our proxy record correlates visually and statistically (cross-spectral analysis) with the atmospheric Δ14C record (solar proxy) and the GISP2 (Greenland Ice Sheet Project Two) δ18O record (climate proxy), showing that solar minima are in phase with drought periods in the northern Great Plains and cold periods in Greenland. This spectral similarity together with phase correlation indicates a possible teleconnection of century-scale global climate fluctuations through common solar forcing.

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