Insolation dependence of the southeastern Subtropical Pacific sea surface temperature over the last 400 kyrs

The present study describes the first sea surface temperature (SST) reconstruction in the southeastern Subtropical Pacific Ocean, offshore the South American coast. The obtained record encompasses the last 400 kyr and follows the characteristic glacial/interglacial pattern defined by global ice volume, However, SST leads the delta O-18 isotopic record reflecting the role of the low latitudes areas in driving climate change. SST in the Holocene is lower by about 0.5-0.8 degreesC than maximal SST in stages 5e, 7, 9 and 11. SST in stages 2-4 is lower by about 0.6-1.3 degreesC than minimal SST in stages 6, 8 and 10. These features are similar to SST records obtained in the South Atlantic Ocean pointing to a general inter-basinal behaviour at these low latitudes. For most of the record, the observed long-term SST evolution is well correlated with the orbital parameter of eccentricity, which modulates the insolation at low latitudes. However, at low eccentricity values (Stages 11-9 and Termination I), SST is driven by obliquity, exhibiting a dependence from high latitude climatic responses.