Quantitative pollen reconstruction of temperature and precipitation in the subtropical-temperate climate transition zone of East-Central China since the Last Glacial Maximum

Abstract

The evolution of the East Asian Summer Monsoon (EASM) under global warming remains uncertain, and the spatiotemporal pattern of the EASM is an ongoing debate. Here, we quantitatively reconstruct high-resolution temperature and precipitation sequences since the Last Glacial Maximum (LGM) by applying the weighted averaging partial least squares (WAPLS) model to the pollen record from Daye Lake in the Taibai Mountains, the main peak of the Qinling Mountain Range. The results show a distinct vegetation succession: the transition from coniferous forest to coniferous-broadleaf mixed forest, and ultimately to deciduous broadleaf forest, with a progressive increase in open land coverage during the late Holocene. The climate during the LGM was characterized by approximately 4 °C lower temperature and about 300 mm less precipitation compared to the Holocene, and then the temperature and precipitation continuously increased from the late deglacial to the early Holocene, reaching the maximum (temperature of 9.9 °C; precipitation of 940 mm) in the mid-Holocene. This warm and humid phase was followed by a cooling and drying trend in the late Holocene. A synthesis of hydrological and temperature records demonstrates that the reconstructed temperature changes were consistent with other temperature records from both the EASM domain and the broader Northern Hemisphere, reflecting a regional signal. However, the reconstructed precipitation data revealed distinct patterns specific to the Qinling region: precipitation changes during the last deglacial period exhibited a homological pattern with records from southern China, while aligning closely with the trends observed in northern China over the Holocene. Millennial-scale precipitation changes during the 16–12 cal kyr BP were modulated by the Atlantic Meridional Overturning Circulation (AMOC) and the Kuroshio Current (KC) intensity. The north-south precipitation dipole pattern in the Holocene is linked to the positions of the Intertropical Convergence Zone (ITCZ), which are modulated by El Niño–Southern Oscillation (ENSO) activity. Both pollen-based reconstructed climate results using the WAPLS model from Daye Lake and CMIP6 multi-model ensemble simulations in the Qinling region suggest that future precipitation will likely increase with rising temperatures, providing critical insights into the response of the EASM to ongoing global warming.