Northern Hemisphere Holocene hydroclimate inferred from a circum-Arctic stack of lake sediment oxygen isotope records from biogenic silica (δ18OBSi)
Lake sediments constitute important terrestrial archives of past climate and environments. While different kinds of proxy data can be obtained from these sediments, oxygen isotopes (δ18O) are of particular interest in paleoclimatology. They record changes of climate and hydrology in a quantitative way. Commonly, δ18O is measured on carbonates (i.e. ostracods) and biogenic silica (mainly diatoms). While oxygen isotopes in lacustrine carbonates (δ18OCaCO3) have been studied extensively for several decades, they are subject to complex species-dependent fractionation processes and not available globally. Lacustrine oxygen isotope records from biogenic silica (δ18OBSi), on the other hand, likely do not display species-dependent fractionation effects (or only very minor) and offer insight even in data-sparse regions devoid of carbonates, such as the Arctic. More than 40 lacustrine δ18OBSi records from mid- and high-latitude regions of the northern hemisphere have been published to date. Interpreting case studies of δ18OBSi, however, is challenging due to a complex interplay of climatic and hydrological factors. Therefore, these individual case studies have been complemented with additional efforts addressing climatic and hydrological backgrounds, laboratory techniques, possible species-dependent fractionation as well as deposition and dissolution effects. Here, we combine records from sites across northern Eurasia and North America to a circum-arctic stack in order to infer common underlying trends throughout the Holocene. With this work, we aim at providing new insight on the variability of Holocene hydroclimate as well as on the interplay between lacustrine archives and the δ18O-proxy. This improves both the usability of δ18OBSi for proxy-model comparison and our understanding of the general constraints for interpreting lacustrine δ18OBSi records