Time-transgressive onset of the Holocene Optimum in the East Asian monsoon region

- A 14,000-yr vegetation record was reconstructed from crater lake sediments in Northeast China.
- Spatiotemporal changes of the HO in the East Asian monsoon region were studied.
- The initiation of the HO shifted northward gradually.
- The time-transgressive onset of the HO could be caused by both the temperature and precipitation changes.

The East Asian summer monsoon affects precipitation and hence vegetation in the densely populated Northwest Pacific region, yet a long-standing controversy exists concerning the spatial and temporal dynamics of the Holocene Optimum (HO) in the East Asian Monsoon Region. Here we use a detailed 14,000-year record reconstructing vegetation variations from a strategically selected crater lake from Northeast China, as well as a compilation of previous paleoclimatic studies, to show that the HO began around 6,000 Cal a BP in Northeast China, significantly later than generally recognized. By comparing our paleoenvironmental data with Holocene vegetation records from other regions of East Asia, we identified a marked northward shift for the onset of the HO from ∼10,260Cal a BP in South China to ∼6,000Cal a BP in Northeast China. The gradual northward transgression of the vegetation change could be caused by both the temperature and precipitation changes in different regions. Finally, we fitted a regression model of the start of the HO period versus latitude, which allowed us to make predictions for the beginning of the HO at different geographical locations. This study reveals a strong relationship between latitude and the initiation of the HO, and provides a window towards better understanding the forcing of vegetation changes in the East Asian monsoon region.