Reconstruction of ice conditions in the northern Chukchi Sea during recent centuries: Geochemical proxy compared with observed data

This paper presents the first results of the quantitative reconstruction of ice conditions in the Arctic based on a comparison of the data for periods of meteorological observations with variations in the chemical compositions of the sediments accumulated during the same times. The biogenic elements (Br, Ca, and Sr) and some redox-sensitive (As and Fe) elements are the most informative for the reconstruction of changes in ice conditions with positive correlations, and the lithogenic elements (K and Ti) are predominantly negatively correlated. The reconstruction results for the last 300-400 years of average annual air temperature anomalies for all cores in general terms coincide with the reconstruction for the Northern Hemisphere. The common features of all reconstructions are low temperatures during the Little Ice Age (LIA) and a rapid warming in the middle of the 19th century and in the last decades of the 20th and first decades of the 21st centuries. The results of the reconstruction of the duration of the ice-free period generally coincide with the temperature changes for the last two centuries, although for LIA there is an inverse correlation between the variations in temperature and the duration of the ice-free period. A possible reason for this may be changes in the structure of the surface currents in the Chukchi Sea and the northern part of the Bering Sea, because of which the inflow of warm and freshened waters through the Bering Strait to the Arctic increased occasionally.