Sea surface temperature at the Last Glacial Maximum: A reconstruction using the modern analog technique

Abstract

We have applied the modern analog technique (MAT) to reconstruct sea surface temperature (SST) at the Last Glacial Maximum (LGM) using a database of 292 planktonic foraminiferal samples from the Atlantic, Indian, and Pacific Oceans. LGM SST maps reveal many important patterns and gradients which reflect the climate and circulation patterns of the LGM. One of the most important results is the 2°–6°C mean annual cooling in the central to eastern tropical Atlantic and up 8°C cooling in the eastern tropical Pacific. These changes resulted in an increased east‐west SST gradient in the equatorial regions of these two basins, compared to modern. SSTs in eastern boundary currents of all three ocean basins were cooler than modern at the LGM. Additionally, results indicate more zonal flow patterns in the Kuroshio/North Pacific Current and Gulf Stream/North Atlantic Drift. These changes indicate more intense midlatitude‐to‐equator SST gradients at the LGM, which likely resulted in more intense circulation and increased zonal winds. SSTs in much of the tropical and northern Indian Ocean were within 2°C of modern temperatures. Consistent with the results of previous studies, results indicate little change in much of the western tropics and the subtropics of all ocean basins.