Inconsistent patterns of Holocene rainfall changes at the East Asian monsoon margin compared to the core monsoon region

Abstract

Documenting spatiotemporal patterns of the Holocene Optimum (HO) at the climatically sensitive East Asian monsoon (EAM) margin are essential for understanding monsoon climate dynamics. However, the timing of the onset of the HO at the EAM margin is still debated and progress has been partly hindered by age uncertainties in different proxy records. To avoid the bias of these chronological uncertainties, we compared moisture variations from the marginal EAM region reconstructed from dust and aluminum (Al) flux records with tree pollen percentages in a dated lake sediment core that tracked moisture changes in the region around the lake. We show a delay (∼1500 years) of HO initiation in the core EAM region in northeastern China compared to the monsoon margin. Synthesizing pollen records with reliable chronologies show a synchronous HO occurrence at ∼8000-7000 cal yr BP at the monsoon margin, which is likely attributed to the shrinkage of the Northern Hemisphere ice sheet. Therefore, although the monsoon margin has always been considered a climate-sensitive area, it might be sensitive to different forcing factors from the core monsoon region.