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 δ 18O,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 Nio 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.
The equatorial Pacific underwent a significant climate transition during the late Pliocene, which is characterized by cooling of global sea surface temperatures (SSTs) and formation of a marked SST gradient between the eastern and western equatorial Pacific. Moreover, this transition was nearly synchronous with the late Pliocene Northern Hemisphere glaciation. Probing the relationship among solar insolation, low and high latitude processes is the key to unravel the mechanism of this climate transition. A series of statistical methods were used in this study to analyze the orbital components of the equatorial Pacific SST and global ice volume records for the past 5 Ma. We found that integrated solar insolation rather than the monthly mean insolation is the primary external forcing of the late Pliocene climate transition, and that on orbital time scale the SSTs of the eastern and western equatorial Pacific display consistent change rather than a "seesaw" pattern. Changes of Earth’s orbital configuration have been responsible for this climate transition whereas the feedback effects of atmospheric CO2 concentration have further cooled the global climate since the early Cenozoic.
