A team of researchers from the Institute of Earth Environment, Chinese Academy of Sciences, led by Associate Researcher Zhao Jiaju, in collaboration with Lanzhou University and the Institute of Tibetan Plateau Research, Chinese Academy of Sciences, conducted a study on long-chain alkenones and long-chain alkyl esters at Lake Dali to quantitatively reconstruct early spring water temperature, eliminating the influence of species factors. The findings of this study were recently published in Quaternary Science Reviews.
The study reconstructed the proportion changes of Group 2i species in Lake Dali during the cold season and found a decreasing trend in the proportion of late Holocene cold-season species (Group 2i). This trend may be controlled by winter sunshine duration and atmospheric CO2 concentration-driven winter temperatures.
In Lake Dali, dominated by cold-season Group 2i species, the team selected samples with a predominance of cold-season species to reconstruct early spring lake water temperature in the late Holocene. The reconstructed temperatures from long-chain alkenones and the changes in the proportion of cold-season Group 2i species indicate a long-term warming trend during the cold season (winter and early spring) in Lake Dali during the late Holocene.
The study also found a significant increase in the proportion of cold-season Group 2i species during the period of 4.3-3 ka BP, accompanied by a reconstructed temperature decrease of 5-6 degrees Celsius. This may be closely related to a significant expansion of Arctic winter sea ice. The sudden cooling led to a reduction in precipitation from the northern Chinese monsoon and ecosystem deterioration.
Related Paper: https://doi.org/10.1016/j.quascirev.2024.108594
