Indian Ocean surface circulation is an important part of the global ocean conveyor belt, and is connected via two important gateways including the Indonesian Throughflow, and the Agulha Leakage. Changes in the surface hydrography of the Indian Ocean may therefore impact on the global overturning circulation. Here we present spectral, and cross spectral analysis results which show that Indian Ocean surface salinity and temperature increased during glacial intensification, with a significant lag prior to deglaciations.