Reconstruction of temperature and precipitation spanning the past 28 kyr based on branched tetraether lipids from Qionghai Lake, southwestern China

The Indian summer monsoon (ISM) significantly influences the climate of southwestern China; however, continuous quantitative temperature reconstructions since the Last Glacial Maximum are rare, which limits our understanding of ISM evolution. In this study, we analyzed the branched glycerol dialkyl glycerol tetraethers (brGDGTs) from a lacustrine sediment core from Qionghai Lake to reconstruct the paleoclimatology of southwestern subtropical China over the past 27.7 kyr. Our results suggest that the brGDGTs in Qionghai Lake sediments were probably sourced from catchment soils, with some contributions from in situ lacustrine production. We found that the temperature of the Last Glacial Maximum and Holocene Climatic Optimum was similar to 3 degrees C cooler and similar to 2.5 degrees C warmer than present-day conditions, respectively, based on brGDGTs-reconstructed mean annual air temperatures (MATs). Generally, temperature and precipitation showed synchronous paleovariability in ISM regions. Moreover, Northern Hemisphere summer insolation was the dominant control on climate variability in ISM regions on the precessional scale, while Atlantic Meridional Overturning Circulation activity, Intertropical Convergence Zone positioning, and glacial boundary conditions (ice sheet extent and sea surface temperature) contributed to climate shifts on millennial timescales.

Automated summary

This study reconstructed the paleoclimate of southwestern subtropical China over the past 27.7 kyr by analyzing brGDGTs in lake sediment, revealing that the temperature during the Last Glacial Maximum and Holocene Climatic Optimum was cooler by about 3 degrees C and warmer by about 2.5 degrees C than present conditions, based on brGDGT-reconstructed mean annual air temperatures (MATs). Additionally, temperature and precipitation in ISM regions showed synchronous paleovariability, with North Hemisphere summer insolation being the dominant factor on precessional scale climate variability.