Possible solar forcing of 400-year wet-dry climate cycles in northwestern China
2009
Wu, Jinglu | Yu, Zicheng | Zeng, Hai'Ao | Wang, Ninglian
Here we present a multi-proxy paleolimnological record from a closed-basin lake (Ebinur Lake) in northwestern China to investigate climate change in this arid region during the last 1,500 years. The 120-cm long sediment core was dated by AMS radiocarbon and ²¹⁰Pb methods. The fine-grained clay sediments contain 3-17% organic matter (OM) and 9-31% carbonate, and are interrupted by multiple sand and silt layers. These sand/silt layers, having consistently low OM, were found at 700-800, 1000-1100, 1300-1400, and 1700-1750 a.d., with a time spacing of 300-400 years. We interpret that the low OM sand/silt layers were deposited during higher lake levels caused by increased river inflow from the surrounding mountains during wet climate intervals. This interpretation is supported by concurrent decreases in δ ¹⁸O and δ ¹³C of bulk carbonate and in carbonate content. Wet climate intervals at 700-800 a.d. and at 1700-1750 a.d. also correlate with elevated snow accumulation and low δ ¹⁸O from Guliya ice core on the NW Tibetan Plateau, both regions strongly influenced by the westerlies. This approximate 400-year periodicity of wet-dry climate oscillations appear to correlate with solar activity as shown by atmosphere ¹⁴C concentration and with paleo-moisture records in interior North America. Our results suggest that solar activities might have played a significant role in driving wet-dry climate oscillations at centennial scales in the interior of Eurasian continent.
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