The Kuroshio Current is a western boundary current in the North Pacific Ocean that facilitates the movement of warm, saline water from low to mid-latitudes, exerting considerable influence on China, East Asia, and global climate as a whole. Alterations of the Kuroshio Current before the Industrial Revolution remain poorly understood, mainly due to a lack of observational data.
In this article we are going to tell you everything there is to know about the Kuroshio current deceleration and what negative effects they can have on our planet.
Research on the deceleration of the Kuroshio current
A recent study by a research team led by Professor Hu Shijian at the Institute of Oceanology of the Chinese Academy of Sciences (IOCAS) examined the Sr/Ca ratios of Porites coral from southern Taiwan, possibly reflecting long-term fluctuations of the Kuroshio Current.
The research has been published in the journal Global and Planetary Change. Since the Kuroshio Current exerts a significant influence on the hydrographic conditions of the sea surface, variations in sea surface temperature can serve as an indicator of alterations in the Kuroshio Current.
Fluctuations in the Kuroshio current
Hu and his team found that the monthly Sr/Ca ratio in corals, which serves as a reliable indicator of sea surface temperature, has the ability to document interannual variations in Kuroshio transport. Using this indicator, They were able to create a continuous reconstruction of Kuroshio transportation spanning the years from 1788 to 2013.
"The data indicate a steady decline in Kuroshio transport since 1788, accompanied by an accelerated rate of decline from the 1950s onwards, presumably as a result of rapid ocean warming," said Li Xiaohua, lead author of the study.
In addition, researchers have indicated that alterations in the latitude of the North Equatorial Current bifurcation, the phase transition of the The Pacific Decadal Oscillation and El Niño-Southern Oscillation have also affected the observed variations in the Kuroshio Current.
Professor Hu, corresponding author of the study, said: “This research provides a practical example of alterations in ocean currents by applying coral geochemical indices, and fossil corals can serve as valuable tools to monitor changes in paleocurrents in future research.”
History
This current was discovered in 1565, when the Guipuzcoan Andrés de Urdaneta, colonial administrator, supervisor of nautical expeditions, corregidor, Augustinian monk and devoted navigator in the service of King Philip II, made a significant discovery while aboard the Nao San Pedro. He was the first to establish the "tornaviaje", a return route between Cebu in the Philippines and the coasts of Antigua California in New SpainThis revelation about the return voyage granted Spain unrivaled dominion over the Pacific Ocean for centuries, a dominion exemplified by the famous "Manila Galleon."
Geography of the Kuroshio Current
The Kuroshio River, characterized by its narrow width and warm, fast-flowing waters, has its daily documented path south of Japan. It is flanked by the North Pacific Current to the north, the California Current to the east, and the North Equatorial Current to the south. This warm current plays a vital role in maintaining Japan's coral reefs, which are recognized as the northernmost coral reefs in the world. In addition, the Tsushima Current is a branch of the Sea of Japan. The Japan Current also contributes to the temperate climate seen along the southern coast of Alaska and in British Columbia.
The journey begins at the point where the current north of the equator approaches the Philippines. It crosses Kyushu and the Ryukyu Archipelago, creating what is known as the China Sea Bend, and proceeds through the Tokara Strait, making a sharp turn north. At this point, when the speed of the current is at its maximum, it splits into two paths: one moves away from the Japanese coasts, while the other follows a more intricate and winding route, staying relatively close to the coast until both branches converge near 35° north latitude and 141° east longitude.
The Kuroshio Current then moves eastward away from the Japanese coast and transforms into what is known as the Kuroshio Spread. This spread gains significant strength and exhibits considerable instability until it reaches the Emperor Seamounts, a chain of underwater volcanic mountains, where it disperses into several subcurrents, some of which will eventually merge with the North Pacific Current.
Satellite images of the Kuroshio Current reveal the meandering path of the current, which creates isolated rings or eddies that measure approximately between 100 and 300 km in diameter. These eddies maintain their distinctive shape for several months and exhibit unique biological characteristics that are influenced by their location of formation. When eddies form between the current and the Japanese coast, they can affect the continental shelf.
The high kinetic energy associated with these eddies results in the movement of significant water masses toward one side of the ring while simultaneously introducing water on the opposite side. The strength and size of these eddies decrease as they move away from the primary ocean currents.
Biodiversity
Boundary currents in western regions facilitate rapid transport of organisms over considerable distances, and numerous commercially important marine species migrate within these currents as they complete their life cycles. A substantial portion of the The world's oceans are occupied by subtropical gyres, which have become more productive than in their initial state.Furthermore, their role in carbon dioxide fixation contributes significantly to the global atmospheric carbon dioxide budget.
I hope that with this information you can learn more about the slowdown of the Kuroshio current and its consequences.