Dates of Holocene environmental changes in Lake Bafa: A hierarchical Bayesian analysis of change points

Abstract

The timing of the separation of Lake Bafa from the Aegean Sea and its subsequent transition to a lake remains a topic of debate, with considerable uncertainties associated with the proposed dates for these transitions. This study introduces a novel approach, hierarchical Bayesian change point analysis (HBCPA), to identify tipping points in paleoenvironmental time series. The objective is to offer more precise and objectively selected results concerning the previously uncertain transition dates of Lake Bafa’s geological evolution in the Holocene. The method presented in this study is applied to analyze stable oxygen and carbon isotope data from foraminifer and ostracod shells, as well as total organic carbon (TOC) data, obtained from the BAFA09P02 sediment core. Results indicate that the transition from a marine to an isolated lagoon environment occurred around 2060 years BP, with an 89% uncertainty interval ranging from 2250 to 1870 years BP. Additionally, the transition from an isolated lagoon to a brackish lake environment is estimated to have occurred around 595 years BP, with an 89% uncertainty interval ranging from 780 to 425 years BP. The results of this study illustrate that the suggested HBCPA approach holds the capability to identify tipping points in environmental data while quantifying their intrinsic uncertainties.