Search

Understanding the variability and related dynamic mechanisms of the Indian summer monsoon evolution over the past millenniums is crucial for disaster prevention and mitigation in the context of strengthening global warming. Here, we present a high‐resolution hydroclimate reconstruction over the past 3110 years in northwestern Yunnan Province, southwestern China, based on grain size analysis using the End‐member modeling algorithm and other environmental proxies. The results indicate that the temperature in northwestern Yunnan Province generally decreased since 3110 cal. yr BP, aligning with other temperature records on regional and global scales. Precipitation in the study area remained relatively stable before 1000 cal. yr BP, but exhibited an obvious out‐phase change compared with the temperature records over multidecadal to centennial timescale. While after 1000 cal. yr BP, the precipitation steadily increased, revealing the hydroclimate pattern of notably dry Medieval Warm Period (MWP) and relatively wet Little Ice Age (LIA) in the study area. The decoupling combination of temperature and precipitation spanning the MWP and LIA in southwestern China contrasts with that in the East Asian summer monsoon area and the Indian subcontinent which is also controlled by the Indian summer monsoon, indicating the spatial heterogeneity of precipitation in the Asian summer monsoon region. The discussion about dynamic mechanisms points out that solar activity emerges as a significant factor influencing regional temperature changes, and El Niño‐Southern Oscillation and Intertropical Convergence Zone migration jointly impact the precipitation change in the study area and the hydroclimate discrepancy in the Asian summer monsoon region. Plain Language Summary: Knowledge of the Indian summer monsoon evolution over the past millennium is vital for addressing the challenges posed by global warming. In this study, we present a high‐resolution hydroclimate reconstruction covering the last 3110 years in northwestern Yunnan Province, southwestern China. Using the End‐member Modeling Algorithm and multiple environmental proxies, we found a general temperature decrease since 3110 cal. yr BP, consistent with global and regional trends. Before 1000 cal. yr BP, precipitation in the study area remained stable but showed a distinct antiphase pattern with temperature variations over multidecadal to centennial timescales. After 1000 cal. yr BP, precipitation steadily increased, revealing a notably dry Medieval Warm Period (MWP) and a relatively wet Little Ice Age (LIA). The decoupling of temperature and precipitation during the MWP and LIA in southwestern China contrasts with the East Asian summer monsoon and the Indian subcontinent, highlighting the spatial heterogeneity of precipitation in the Asian summer monsoon (ASM) region. Our discussion on dynamic mechanisms highlights the significant role of solar activity in regional temperature changes and the joint impact of El Niño‐Southern Oscillation and Intertropical Convergence Zone migration on precipitation in the study area and the broader ASM region. Key Points: Precipitation change in the study area was indicated by the relative proportion of end membersDecoupling warming and monsoon precipitation in northwestern Yunnan Province was revealedEl Niño‐Southern Oscillation and Intertropical Convergence Zone migration jointly impact the hydroclimate discrepancy in the Asian summer monsoon region [ABSTRACT FROM AUTHOR]

Our knowledge about the interaction between human activities and the environment in the middle-late Holocene remains incomplete. Core C1 in Lake Chaohu from the middle and lower reaches of Yangtze River (MLYR), eastern China, provides an opportunity to investigate vegetation and climate changes, human activities, and East Asian summer monsoon (EASM) evolution since 5100 cal. yr BP. These variables are assessed based on radiocarbon dating, pollen and charcoal records, and magnetic susceptibility (χlf), median grain size and TP. Results reveal a hiatus in sedimentation between 2080 and 730 cal. yr BP in the western part of Lake Chaohu, which is common in most lakes in the MLYR. Evergreen and deciduous broadleaved mixed forest retreated gradually after 3650 cal. yr BP, and was replaced by secondary Pinus forest after at least 730 cal. yr BP. Intense agricultural activities and vegetation clearance are first detected at 2520 cal. yr BP. Human settlements expanded from the lake front wetlands (during the period 2520–2080 cal. yr BP) to remote high-altitude areas (2080–100 cal. yr BP), and then returned to the lake front to reclaim the wetlands and lake (after 400 cal. yr BP). A gradual trend of recessional EASM strength from 4300 cal. yr BP and centennial-scale variations of EASM during the period 5100–3650 cal. yr BP are revealed. The reduction of summer insolation, southward shift of the ITCZ, and El Niño Southern Oscillation may control the intensity of EASM and climate on a large regional scale. [ABSTRACT FROM AUTHOR]