Sea surface temperature anomalies in the oceans at the LGM estimated from the alkenone-U37K′ index:: comparison with GCMs -: art. no. L03208

U-37(K') sea surface temperature (SST) estimates for the Last Glacial Maximum (LGM) are discussed and compared to coupled general circulation model (GCM) results. We conclude that U-37(K') estimates and most numerical models agree in the magnitude of the large scale SST cooling features of the glacial ocean. There was a larger cooling in the northern than in the Southern Hemisphere. The eastern boundary currents and equatorial regions were also colder. There is a consensus between models and alkenone data for a tropical cooling of about -2degreesC, which is in disagreement with both a smaller cooling as suggested by the CLIMAP project reconstruction, or a more pronounced cooling as suggested from coral proxy records. The comprehensive HadCM3 simulation examined reproduces a puzzling feature of the U-37(K')-SST reconstruction, i.e., the warming of the glacial north Atlantic, which needs further investigation using numerical modelling and proxy data reconstruction.