Concurrent mid-Holocene East Asian temperature and summer monsoon maxima forced by high- and low-latitude interplay

Holocene evolution of the East Asian summer monsoon (EASM), which provides precipitation to 1.6 billion people and has played a key role in the development of Chinese civilizations, has been hypothesized to be driven directly by summer insolation changes. However, an insolation-driven early-Holocene EASM maximum has not been convincingly validated, because a mid-Holocene summer monsoon precipitation maximum is widely accepted and the timing of a warm-season temperature maximum, which drove the strongest summer monsoon, is still unknown. Here we show that a pronounced shift in diatom life strategy, registered in high-resolution lake sediment records from northern China, tracked a clear change in lake thermal regime triggered by higher mid-Holocene warm-season temperatures. Combined with robust pollen-inferred precipitation data from northern China, we present independent lines of evidence that the East Asian thermal and summer monsoon maxima occurred synchronously during the mid-Holocene, demonstrating that a high- and low-latitude interplay is the most probable mechanism for the EASM throughout the Holocene. This hypothesis may explain both the mid-Holocene maximum of summer monsoon precipitation and the mid-Holocene flourishing of the Neolithic Chinese Yangshao culture in northern China.