Long-term variability of the Kuroshio since 1788 based on coral records

Abstract

The Kuroshio transports warm water poleward from low- to mid-high latitude regions and strongly affects ocean-atmosphere-land interactions. Previous studies have shown that the Kuroshio has strengthened at its origin during recent decades. However, changes in the Kuroshio on a centennial timescale are unclear due to the lack of observations before the Industrial Revolution. In this study, a precisely dated and monthly resolved Porites coral Sr/Ca record from south of Taiwan island, where coral growth is influenced by the Kuroshio, was used to generate a continuous reconstruction of Kuroshio transport (KT) during the period from 1788 to 2013. The data show a consistent decline in KT since 1788, with the rate of decline increasing since the 1950s, probably due to rapid oceanic warming. The southward shift of the bifurcation latitude of the North Equatorial Current, which is related to accelerated global oceanic warming, might have led to the decrease in KT. Natural variability in the phase transition of the Pacific Decadal Oscillation and El Niño-Southern Oscillation might also influence the long-term changes in KT, particularly before the 1950s.