ABSTRACT
Detailed faunal and isotopic studies of Antarctic and sub-Antarctic deep-sea cores indicate that during most of the Late Quaternary (last 200 000 years) climatic changes in the area are in phase or nearly in phase with Northern Hemisphere glacial advances and retreats. However, changes in sub-Antarctic sea surface temperatures in much of the record precede slightly (≃ 3 000 years) changes in Northern Hemisphere glaciers. In the Holocene, for example, sub-Antarctic surface waters reached a temperature maximum ≃ 9 000 years BP, have been cooling since and are today half way between interglacial maximum and glacial minimum temperatures. This provides strong evidence that Southern Hemisphere climates are not being driven by changes in the volume of Northern Hemisphere ice sheets. Furthermore, changes in aerial extent of Antarctic sea ice, probably the most remarkable Pleistocene changes to occur in Antarctic Seas, also precede changes in Northern Hemisphere ice volume.
Power spectrum analysis of the climatic record in sub-Antarctic deep-sea cores shows that the dominant frequencies resolved represent periods of ∼ 100 000 years, 41 000 years and 23 000 years. These are nearly identical to the dominant periods of volume change of Northern Hemisphere glaciers and changes in geometry of the Earth’s orbit. This indicates that major climatic changes on the time scales of ice ages are induced by insolation changes in responses to the changing parameters of the Earth’s orbit around the sun.
