El Niño-Southern Oscillation and East Asian Monsoon controlled Kuroshio Current evolution over the last 42 kyr

Abstract

Kuroshio Current (KC) plays a significant role in global climate change by transporting high-temperature and high-salinity water from low-latitude to mid-high-latitude waters. However, the KC evolution and its main controlling factors remained unclear on the orbital timescales. Here, we research the comprehensive record of high-resolution terrigenous mass accumulation rate (MAR), grain size, SrNd isotopic compositions of clay-size fractions and clay mineral assemblages in core SCS0003 sediments from the northern slope of the South China Sea (SCS) since 42 kyr. The SrNd isotope compositions (<2 μm) and clay minerals illustrate that the smectite mainly came from Luzon Island, with a small content of smectite during the last glacial period, but an increase by about 3–4 times during the Holocene. Furthermore, the smectite MAR flux indicates that the intensity of KC intrusion of the SCS was consistent with the intensity of the open Pacific over the last 42 kyr, which was different from the opposite trend proposed by predecessors. Then it further reveals that the KC was relatively weak and stable in the last glacial period as a whole, but overall became stronger with a larger amplitude in the Holocene, with an increase in the early Holocene and a decline in the middle and late Holocene. Moreover, since 42 kyr El Niño-Southern Oscillation (ENSO) and East Asian monsoon (EAM) controlled by the insolation change in the Earth's precession were the major driving mechanisms of KC evolution, instead of ENSO as the only main controlling factor. On the orbital timescales, our results emphasize that low-latitude processes by the variation of insolation on the precession are very important in driving global climate change, not just high-latitude processes.