Cooler and drier climate in the South–Central Pacific during the last glacial period

Understanding how precipitation responds to temperature change is crucial for anticipating future climate variability. The geological past provides a unique window into rainfall responses to large-scale climate shifts, yet regional responses in the South–Central Pacific remain poorly constrained due to the lack of continuous long-term palaeoclimate records extending beyond the Holocene. To address this gap, we reconstruct temperature and precipitation using biomarker proxies from a 50,000-year peat core from Nuku Hiva, French Polynesia. During the Last Glacial period, increased hydrogen isotopic values of plant waxes indicate drier conditions. Pollen data show increased abundances of drought-adapted herbaceous taxa and reduced cloud forest species. Temperature-sensitive bacterial lipids indicate substantially cooler glacial conditions relative to the Holocene. Notably, reconstructed temperature and precipitation changes are strongly correlated, consistent with data assimilation studies. These results highlight the sensitivity of the tropical Pacific to background climate state and provide important constraints on regional climate dynamics.