Tracking millennial-scale climate variability during the last glacial period using aquatic productivity indicators from Lake Suigetsu, Japan

The East Asian monsoon, critical to nearly half the global population, faces an uncertain future amid rapid climate change. Palaeoclimate records reveal complex and shifting influences over East Asia that have varied across space and time during past episodes of abrupt climate change. Untangling teleconnections that affect East Asian climate requires replicable, high resolution and precisely dated records, yet these are sparsely distributed worldwide. The varved sediments of Lake Suigetsu, Japan, are one such archive, offering significant potential to investigate millennial-scale variability in the East Asian monsoon. Here, we infer lake primary productivity as a tracer of regional climate during the last glacial period from 55 to 20 cal ka BP using sedimentary total organic carbon, biogenic silica and siderite, measured using Fourier transform infrared (FTIR) analyses. Lake productivity exhibits distinct millennial-scale events that align with palaeoclimate inferred from other lakes and speleothems in central Japan which, in turn, indicate a coherent picture of regional-scale hydroclimate variability. The Lake Suigetsu data varies with respect to synchronicity to Greenland ice core records, challenging the assumed spatial and temporal dominance of the North Atlantic and westerly winds on the East Asian monsoon, and supporting an alternative hypothesis of periodic dominance from the Southern Hemisphere. • Lake Suigetsu sediments were investigated using Fourier transform infrared spectroscopy (FTIR). • Primary productivity proxies, TOC and biogenic silica concentrations, reflect changes EASM intensity. • Reveal periodic influence of Southern Hemisphere temperature on EASM in Japan. • Weakened EASM at Lake Suigetsu during prolonged cold stadials linked to Heinrich events. • Extreme North Atlantic climate events with overriding influence over the monsoon.