Contrasting cold season temperature trends between eastern and western mid-latitude Eurasia over the past millennium

Extensive regions of eastern mid-latitude Eurasia have witnessed frequent harsh winters in recent decades, which contrasts with global warming projections. Deciphering the spatial patterns of longer-term cold-season temperature trends across mid-latitude Eurasia and their underlying driving mechanisms is critical for accurately projecting future climatic changes. Here we report a new cold-season temperature record based on freshwater Group 1 alkenone paleothermometer from northeastern China that spans the past 1500 years. We show that, in contrast to long-term warming trends in cold-season temperatures over western mid-latitude Eurasia, large areas of eastern mid-latitude Eurasia display overall cooling trends through the Medieval Climate Anomaly into Little Ice Age. We attribute such spatial heterogeneity in temperature trends to distinct atmospheric circulation patterns modulated by North Atlantic climatic dynamics and the Siberian High. Our study highlights divergent responses of regional cold-season climates to common external forcing under the general scenario of anthropogenic global warming.