Sea-surface temperatures of the southwest Pacific Ocean during the Last Glacial Maximum

The southwest Pacific Ocean covers a broad range of surface-water conditions ranging from warm, salty water in the subtropical East Australian Current to fresher, cold water in the Circumpolar Current. Using a new database of planktonic foraminifera assemblages (AUSMAT-F2), we demonstrate that the modern analog technique can be used to accurately reconstruct the magnitude of sea-surfacetemperature (SST) in this region. We apply this technique to data from 29 deep-sea cores along a meridional transect of the southwest Pacific Ocean to estimate the magnitude of SST cooling during the Last Glacial Maximum. We find minimal cooling in the tropics (0 degrees-2 degrees C), moderate cooling in the subtropical midlatitudes (2 degrees-6 degrees C), and maximum cooling to the southeast of New Zealand(6 degrees-10 degrees C). The magnitude of cooling at the sea surface from the tropics to the temperate latitudes is found to generally be less than cooling at the surface of adjacent land masses.