790,000 years of millennial-scale Cape Horn Current variability and interhemispheric linkages

Abstract

Millennial-scale variations in the strength and position of the Antarctic Circumpolar Current exert considerable influence on the global meridional overturning circulation and the ocean carbon cycle. The mechanistic understanding of these variations is still incomplete, partly due to the scarcity of sediment records covering multiple glacial-interglacial cycles with millennial-scale resolution. Here, we present high-resolution current strength and sea surface temperature records covering the past 790,000 years from the Cape Horn Current as part of the subantarctic Antarctic Circumpolar Current system, flowing along the Chilean margin. Both temperature and current velocity data document persistent millennial-scale climate variability throughout the last eight glacial periods with stronger current flow and warmer sea surface temperatures coinciding with Antarctic warm intervals. These Southern Hemisphere changes are linked to North Atlantic millennial-scale climate fluctuations, plausibly involving changes in the Atlantic thermohaline circulation. The variations in the Antarctic Circumpolar Current system are associated with atmospheric CO ₂ changes, suggesting a mechanistic link through the Southern Ocean carbon cycle.

Abstract

The strength of the Cape-Horn Current, as traced in the sediment cores, varies with sea surface temperature in the Eastern South Pacific. Changes in this current are also associated with North Hemisphere cooling events and atmospheric CO2 outgassing.