Reconstruction of Pacific Ocean bottom water salinity during the Last Glacial Maximum

Abstract

Knowledge of salinity in the deep ocean is important for understanding past ocean circulation and climate. Based on sedimentary pore fluid chloride measurements of a single Pacific site, Adkins et al. () suggested that, during the Last Glacial Maximum (LGM), the Pacific deep bottom water was saltier than expected based on lower sea level alone. Here we present high-resolution salinity profiles from five sites in the South, Equatorial, and North Pacific Ocean. Our study greatly constrains understanding of LGM salinity in the Pacific Ocean. Our results show that LGM chloride concentrations of deep Pacific bottom water were 4.09±0.4% greater than today's values. Pacific Ocean bottom water salinity was also indistinguishable from being homogeneous across the wide range of latitudes studied here. These LGM salinity reconstructions are on average slightly higher (~1.4 to 1% higher) than expected from sea level of the time, which is generally inferred to have been ~120 to ~135 m lower than today. Key Points LGM salinity of Pacific bottom water was 4.09 ± 0.4% greater than today The salinity of bottom waters was homogeneous across latitudes studied Based on sea level, salinity reconstructions were higher than expected values ©2014. American Geophysical Union. All Rights Reserved.