Warming magnitude of Indonesian Throughflow during the penultimate deglaciation (Termination II) and its relationship with climate change in high-latitude regions

Abstract

The tropical oceans are important source areas for global heat and water vapor transport, and changes in tropical sea surface temperature (SST) will have important impacts on high-latitude and global climate change. It is crucial to establish the precise phase relationship between tropical and high-latitude climate variability to gain insight into the mechanisms of global climate change. Here, we present multi-proxy records across the penultimate deglaciation (Termination II) from sediment Core SO18459, which is located in the outflow area of the Indonesian Throughflow (ITF) of the Timor Sea. These proxy records include planktonic and benthic foraminifera δ18O, planktonic foraminifera G. ruber Mg/Ca-derived SST, and δ18Ow of sea surface water. The Mg/Ca-SST records indicate a warming of 4.1°C in the Timor Sea over Termination II, which is in phase with decrease in planktonic and benthic δ18O. Our results suggest that at millennial timescales, climate change of the tropical oceans is synchronous with high-latitude ice volume changes. Furthermore, warming of the Timor Sea is almost simultaneous with warming of the Antarctic, suggesting a rapid heat transfer from the tropics to the Antarctic via the atmosphere and/or ocean circulations. The G. ruber δ18O and SST records of Core SO18459 show a marked YD-like event during Termination II, which is probably caused by decrease in Australian rainfall or strengthening of the Western Pacific Warm Pool. However, a similar YD-like event is not observed in East Asian rainfall records. This discrepancy indicates that different tropical climate systems may have different responses to the same forcing, such as El Nino Southern Oscillation. A similar YD-like event is observed in the global benthic foraminiferal δ18O records during Termination II, implying teleconnection of millennial scale climate change between the tropical regions and high latitudes.