Quantitative climate reconstruction of the Mid- to late Holocene based on pollen records from Northern Shandong, China

Abstract

Pollen serves as a critical proxy for quantitative paleoclimatic reconstruction, with high-quality modern pollen databases and advanced modeling approaches significantly enhancing the reliability of reconstructed climatic parameters and providing multifaceted insights into past climate dynamics. This study presents a quantitative paleoclimatic reconstruction based on pollen analysis from the Dingjiazhuang profile in northern Shandong, China. The LWWA (inverse) model at 900 km was identified as the optimal model for climatic parameter reconstruction. Our results delineate periodic changes of Mid- to Late Holocene climate in the study area through reconstructed curves of annual precipitation (Pann), mean precipitation of the warmest month (MPwa), mean temperature of the warmest month (MTwa), and mean temperature of the coldest month (MTco) spanning 8–2.6 ka. Five distinct climatic phases were identified: A cool-dry fluctuation phase (8.1–6.8 ka), a warm-humid Mid-Holocene Climatic Optimum (6.8–6.2 ka), a transitional cool-humid phase (6.2–5.3 ka), a warm-dry phase (5.3–3.1 ka), and a cool-dry phase (3.1–2.6 ka). Millennial-scale variations were predominantly driven by the interplay between the East Asian Summer Monsoon (EASM) and East Asian Winter Monsoon (EAWM). Centennial-scale anomalies include 8.2 ka, 5.5 ka, and 4.2 ka events. The complex forcing mechanisms underlying these events warrant further investigation. This study represents the first attempt to establish climate quantification in northern Shandong, providing critical data support for understanding the environmental evolution of the East Asian monsoon region during the Holocene.