Temperature Variability in Northeast China over the Past Two Millennia and Linkages with the Arctic Oscillation

Temperature reconstruction over the past two millennia has created a crucial database for global networks and for evaluating and predicting global climate change. Here, we present a high-resolution (~5-25 years) temperature reconstruction over the past 2000 years using branched glycerol dialkyl glycerol tetraethers (brGDGTs) from laminated sediments in a crater lake located in Northeast China. The brGDGT-derived proxies accurately represented the month-above-freezing temperatures (MAFT) within our study region. Our temperature reconstruction exhibited distinct decadal-to-centennial variability and showed rough correspondence with the AO/NAO index and solar activity. Furthermore, the spectral analysis identified two quasi-periodicities of 55-57 and 66-67 years within the MAFTs time series at a 99% confidence level, suggesting possible associations with solar activity. These findings imply that long-term temperature variability in Northeast China is mainly regulated by a combination of the AO, NAO, and solar activity.