Fan et al. (2025) El Niño modulated Holocene hydroclimate extremes as a dipolar pattern of droughts in northeastern China and floods in southwestern China

Identification

• Journal: Scientific Reports
• Year: 2025
• Date: 2025-12-11
• Authors: Jiawei Fan, Hongyan Xu, Fangming Zhang, Hanchao Jiang, Dayou Zhai, Wei Shi, Xiaotong Wei, Wei Zhang, Jule Xiao
• DOI: 10.1038/s41598-025-31443-x

Research Groups

• State Key Laboratory of Earthquake Dynamics and Forecasting, Institute of Geology, China Earthquake Administration, Beijing 100029, China
• State Key Laboratory of Earthquake Dynamics and Forecasting, Institute of Geophysics, China Earthquake Administration, Beijing 100081, China
• State Key Laboratory of Earthquake Dynamics and Forecasting, Peking University, Beijing 100871, China
• Yunnan Key Laboratory for Paleobiology, Institute of Paleontology, Yunnan University, Kunming 650500, China
• State Key Laboratory of Atmospheric Environment and Extreme Meteorology, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
• CAS Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
• CAS Center for Excellence in Life and Paleoenvironment, Beijing 100044, China
• College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China

Short Summary

This study reconstructs Holocene hydroclimate from Yangzong Lake, southwestern China, revealing a dipolar pattern of increasing floods in the southwest and droughts in the northeast, modulated by El Niño events, which resolves discrepancies in past monsoon-ENSO relationships.

Objective

• To investigate Holocene summer monsoon precipitation and inter-annual- to decadal-scale extreme climate events in southwestern China.
• To detect the spatial pattern of extreme climate events across southwestern and northeastern China.
• To reveal the causal relationship between these extreme events and El Niño events.

Study Configuration

• Spatial Scale: Regional scale, focusing on southwestern China (Yangzong Lake, Beihai Wetland, Muge Co Lake) and northeastern China (Daihai Lake, Dali Lake, Hulun Lake, Gonghai Lake), within the broader Asian monsoon region.
• Temporal Scale: Holocene epoch (last 12,000 years), with reconstructions at high resolution (~5.5 years) allowing for analysis of inter-annual to decadal, and centennial to millennial timescales.

Methodology and Data

• Models used:
  • End-member (EM) modeling (lognormal algorithm in AnalySize software) for grain-size data.
  • Bayesian accumulation model (OxCal 7.1 program with IntCal20 data) for age-depth chronology.
  • REDFIT program for spectral analysis of time series (OFAC = 4, HIFAC = 1, Welch type spectral window).
• Data sources:
  • Sediment core (YZ22A) from Yangzong Lake, southwestern China.
  • Grain-size distributions (Malvern Mastersizer 3000 laser grain-size analyzer).
  • Elemental contents (X-ray fluorescence (XRF) scanning, Itrax core scanner).
  • Radiocarbon dating (14C ages of charcoal samples).
  • Paleoclimatic archives from other sites in the Asian monsoon region (e.g., stalagmite δ18O, Ti content, SST reconstruction, sand percentage, pollen assemblages).
  • Historical meteorological data (monthly precipitation from Kunming Meteorological Station, 1981-2010).
  • Numerical simulations and modern observations from existing literature.

Main Results

• A long-term decreasing trend of Indian Summer Monsoon (ISM) precipitation in southwestern China during the Holocene, punctuated by ten centennial- to millennial-scale weak monsoon events (e.g., at 10.1, 9.35, 7.9, 6.85, 6.4, 5.45, 4.8, 2.9, 2.2, and 1.75 ka BP).
• An increase in inter-annual to decadal scale flood events in ISM-dominated southwestern China from ~7500 to 1000 cal yr BP, superimposed on the long-term decreasing ISM precipitation.
• A dipolar hydroclimatic pattern during the middle to late Holocene, characterized by increasing floods in southwestern China and increasing droughts in East Asian Summer Monsoon (EASM)-dominated northeastern China.
• This dipolar pattern correlates with an increasing occurrence of El Niño events since ~7500 cal yr BP.
• The proposed mechanism involves a strengthened and southwestward-shifted West Pacific subtropical high (WPSH) during El Niño conditions, which blocks northeastward moisture transport to southwestern China (causing floods) and impedes northward moisture flow to northeastern China (causing droughts).
• Spectral analyses reveal quasi-periodicities (e.g., 52.8, 28.2, 24.3, 18.8, 13.5, 12.8, 12.3, and 11.5 years) in extreme climate events, similar to or harmonic with atmospheric Δ14C and ENSO activity, suggesting solar activity as a fundamental driver mediated by ENSO.

Contributions

• Provides a 12,000-year high-resolution hydroclimatic reconstruction from southwestern China, resolving discrepancies between centennial-scale weak ISM precipitation during El Niño and historical extreme precipitation in the region.
• Identifies a novel dipolar pattern of Holocene hydroclimate extremes (floods in southwest, droughts in northeast China) linked to El Niño events.
• Elucidates the causal mechanism for this dipolar pattern, involving the modulation of the West Pacific subtropical high and atmospheric circulation by El Niño.
• Contributes to a better understanding of short-term spatiotemporal heterogeneity of extreme climate events in the Asian monsoon region under natural variability and increasing complexity of El Niño dynamics under global warming, informing mitigation strategies for regional hydroclimatic hazards.

Funding

• National Natural Science Foundation of China (U22A20562, 42372214)
• State Key Laboratory of Earthquake Dynamics and Forecasting (LED2022A06)

Citation

@article{Fan2025El,
  author = {Fan, Jiawei and Xu, Hongyan and Zhang, Fangming and Jiang, Hanchao and Zhai, Dayou and Shi, Wei and Wei, Xiaotong and Zhang, Wei and Xiao, Jule},
  title = {El Niño modulated Holocene hydroclimate extremes as a dipolar pattern of droughts in northeastern China and floods in southwestern China},
  journal = {Scientific Reports},
  year = {2025},
  doi = {10.1038/s41598-025-31443-x},
  url = {https://doi.org/10.1038/s41598-025-31443-x}
}