Central Pacific hydroclimate over the last 45,000 years: Molecular-isotopic evidence from leaf wax in a Hawaiʻi peatland

Long-term hydroclimate variability at low latitudes exerts a strong influence on global climate, yet its timing and mechanisms are poorly documented for the central Pacific region. Here we present molecular hydrogen isotopic compositions of long-chain n-alkanes in montane wetland deposit Mount Kaʻala Island Oʻahu, Hawaiʻi, which document hydrological conditions related vegetation changes over late Pleistocene Holocene. To aid interpretation fossil n-alkanes, also determine chain-length distributions most common bog plants growing locally. Organic matter accumulation started around 45 ka BP, one oldest reported dates peat-forming ecosystems Hawaiʻi. Sedimentary n-alkane suggest shifts driven by rainfall regime, especially with enhanced abundances shorter chain length homologues during wet periods. Depleted values δ2H dated to ca 45–40, 24–22.5, 19–16.5, 10–6 BP generally coincide faster carbon rates, may indicate winter cyclonic storm precipitation, as suggested modern rainwater isotope data. For Late Pleistocene, consistency direction Kaʻala, dynamics Mauna Kea ice cap, precipitation Cariaco basin, East Asian monsoon intensity that southward mean position ITCZ contributed greater frequency extratropical storms, increasing leeward high-elevation sites. During Holocene, ITCZ-hydroclimate linkage is inverted, consistent dominated ENSO variability.