Coupling of the Intertropical Convergence Zone and Southern Hemisphere mid-latitude climate during the early to mid-Holocene

Conceptual models predict a tight coupling between the Intertropical Convergence Zone (ITCZ) and the Southern Westerly Winds (SWW) in response to glacial-interglacial transitions, yet little is known about this relationship under Holocene boundary conditions. Here we present a synthesis of Holocene pollen data from the southwest Pacific mid-latitudes that tracks changes in the SWW. Comparison of our SWW paleoclimate records with data tracking the ITCZ, oceanic circulation, and insolation reveals clearly synchronous and in-phase ITCZ-SWW dynamics between 12 and 5 ka, indicating a tight coupling between the tropics and southern mid-latitudes in response to ocean circulation and insolation. An apparent decoupling of the SWW and ITCZ in the Pacific region after 5 ka is attributable to the overriding influence of the El Niño–Southern Oscillation (ENSO) over the proxy data.