Stable oxygen and carbon isotope ratios of Globigerinoides sacculifer of ODP Hole 134-828A from the Southwest Pacific (Table 2)

Oxygen-isotope analyses of planktonic foraminifera from 57 western Pacific deep-sea cores are compared for the Holocene and the Last Glacial Maximum (LGM). Carbonate dissolution, sedimentation rates/bioturbation, sample density, and vital effects are assessed before the sea-surface salinity signal of these records is reconstructed. Average glacial-interglacial Delta delta18O values in the western Pacific are found to be close to those in the Atlantic Ocean (1.76 ‰ in the Pacific compared to 1.80 ‰ in the Atlantic), questioning previous suggestions of a larger salinity difference between the Atlantic and the Pacific oceans during the LGM. During the LGM, sea-surface salinity was higher in the western Pacific than today (by >~1 ‰), implying that evaporation minus precipitation was higher all over the region. The minimum change in sea-surface salinity occurred around the equator at the core of the Western Pacific Warm Pool. Holocene high-amplitude, high-frequency fluctuations in planktonic delta18O records north and south of the present limits of the Western Pacific Warm Pool are indicative of sea-surface temperature and/or sea-surface salinity variations related to its expansion and contraction at the scale of thousands of years. Such high-amplitude, high-frequency fluctuations at the edge of the WPWP are best documented in the delta18O signal of ODP Hole 828A offshore Vanuatu, so far the best high-resolution record for the western Pacific.