Led by Cardiff University's Prof Ian Hall, they will drill into the ocean floor off the coast of South Africa.
They want evidence to explain the driving role of the Agulhas current.
It mostly transports vast amounts of warm, salty water towards the tip of South Africa but "leaks" elsewhere.
Some of the water leaks into the Atlantic Ocean in massive swirls, known as Agulhas rings.
It can make its way into the North Atlantic via the Gulf Stream where it eventually cools and sinks, transporting more water northward and maintaining the global conveyer belt of ocean currents.
Prof Hall and his team from the International Ocean Discovery Programme Expedition 361 will collect sediment cores from the ocean floor to gain an understanding of how this leakage may have influenced changes in the climate.
"We already have tantalizing evidence... that suggests that leakage from the Agulhas current has been involved in large global climate swings over the past 100,000 years, including the drastic global warming after the last ice age.
"By examining these sediment cores closer, we expect to find evidence of how the Agulhas current has influenced the regional and global climate over much longer timescales, and therefore detail how connections within the climate system work.
"This has implications for understanding how the future climate system may operate in a warming world."
Researchers will head to the Indian Ocean to study one of Earth's strongest currents and its influence on global climate over the last five million years.