Combined results of proxy analyses for sediment core EN21449-1 from the Republic of Sakha (Yakutia), Siberia. The sediment core was obtained during fieldwork in August 2021, jointly organized by the Alfred Wegener Institute and the North-Eastern Federal University of Yakutsk. A comprehensive description of fieldwork in 2021 is available in the corresponding expedition report (Morgenstern et al., 2023). The sediment core was subsampled in consecutive 1 cm intervals, and subsamples were used for radiometric (lead-210 and cesium-137) age dating, mercury measurements, macroscopic charcoal (>150 μm) and pollen and non-pollen palynomorph analyses. These data can be used to assess the past environmental dynamics around Lake 449.